From ffe0eec4072df9de5970570ec07068dbd7961ff2 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 13:47:59 +0100
Subject: [PATCH 01/29] Introduce the kata and document steps

---
 test-pnpm/morning_routine/README.md    |   0
 test-pnpm/shopping-cart-kata/README.md | 222 +++++++++++++++++++++++++
 2 files changed, 222 insertions(+)
 delete mode 100644 test-pnpm/morning_routine/README.md
 create mode 100644 test-pnpm/shopping-cart-kata/README.md

diff --git a/test-pnpm/morning_routine/README.md b/test-pnpm/morning_routine/README.md
deleted file mode 100644
index e69de29..0000000
diff --git a/test-pnpm/shopping-cart-kata/README.md b/test-pnpm/shopping-cart-kata/README.md
new file mode 100644
index 0000000..222b9bd
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/README.md
@@ -0,0 +1,222 @@
+# What do we want to build?
+
+We are building a shopping cart for an online grocery shop. The idea of this kata is to build the product in an iterative way.
+
+### Technical requirements
+
+- The price per unit is calculated based on the product cost and the percentage of revenue that the company wants for that product.
+- The price has to be rounded up; so if a price per unit calculated is 1.7825, then the expected price per unit for that product is 1.79
+- The final price of the product is then calculated as the **price per unit with the VAT rounded up**.
+- Products are not allowed to have the same name.
+
+### List of products
+
+| **Name**   | **Cost** | **% Revenue** | **Price per unit** | **Tax**               | **Final price** |
+| ---------- | -------- | ------------- | ------------------ | --------------------- | --------------- |
+| Iceberg 🥬 | 1.55 €   | 15 %          | 1,79 €             | Normal (21%)          | 2.17 €          |
+| Tomato 🍅  | 0.52 €   | 15 %          | 0.60 €             | Normal (21%)          | 0.73 €          |
+| Chicken 🍗 | 1.34 €   | 12 %          | 1.51 €             | Normal (21%)          | 1.83 €          |
+| Bread 🍞   | 0.71 €   | 12 %          | 0.80 €             | First necessity (10%) | 0.88 €          |
+| Corn 🌽    | 1.21 €   | 12 %          | 1.36 €             | First necessity (10%) | 1.50 €          |
+
+### List of discounts
+
+| **Discounts code** | **Amount** |
+| :----------------: | ---------- |
+|      PROMO_5       | 5%         |
+|      PROMO_10      | 10%        |
+
+### Use cases
+
+#### List the shopping cart
+
+> ```
+> As a customer
+> I want to see my shopping cart
+> ```
+
+#### **Empty cart**
+
+```
+--------------------------------------------
+| Product name | Price with VAT | Quantity |
+| -----------  | -------------- | -------- |
+|------------------------------------------|
+| Promotion:                               |
+--------------------------------------------
+| Total products: 0                        |
+| Total price: 0.00 €                      |
+--------------------------------------------
+```
+
+#### Add product to shopping cart
+
+> ```
+> As a customer
+> I want to add Iceberg 🥬 to my shopping cart
+> I want to add Tomato  🍅 to my shopping cart
+> I want to add Chicken 🍗 to my shopping cart
+> I want to add Bread 🍞 to my shopping cart
+> I want to add Corn 🌽 to my shopping cart
+> I want to see my shopping cart
+> ```
+
+```
+--------------------------------------------
+| Product name | Price with VAT | Quantity |
+| -----------  | -------------- | -------- |
+| Iceberg 🥬   | 2.17 €         | 1        |
+| Tomato  🍅   | 0.73 €         | 1        |
+| Chicken 🍗   | 1.83 €         | 1        |
+| Bread 🍞     | 0.88 €         | 1        |
+| Corn 🌽      | 1.50 €         | 1        |
+|------------------------------------------|
+| Promotion:                               |
+--------------------------------------------
+| Total products: 5                        |
+| Total price: 7.11 €                      |
+--------------------------------------------
+```
+
+#### Add product to shopping cart
+
+> ```
+> As a customer
+> I want to add Iceberg 🥬 to my shopping cart
+> I want to add Iceberg 🥬 to my shopping cart
+> I want to add Iceberg 🥬 to my shopping cart
+> I want to add Tomato  🍅 to my shopping cart
+> I want to add Chicken 🍗 to my shopping cart
+> I want to add Bread 🍞 to my shopping cart
+> I want to add Bread 🍞 to my shopping cart
+> I want to add Corn 🌽 to my shopping cart
+> I want to see my shopping cart
+> ```
+
+```
+--------------------------------------------
+| Product name | Price with VAT | Quantity |
+| -----------  | -------------- | -------- |
+| Iceberg 🥬   | 2.17 €         | 3        |
+| Tomato  🍅   | 0.73 €         | 1        |
+| Chicken 🍗   | 1.83 €         | 1        |
+| Bread 🍞     | 0.88 €         | 2        |
+| Corn 🌽      | 1.50 €         | 1        |
+|------------------------------------------|
+| Promotion:                               |
+--------------------------------------------
+| Total products: 8                        |
+| Total price: 12.33 €                     |
+--------------------------------------------
+```
+
+#### Apply discount to the shopping cart
+
+> ```
+> As a customer
+> I want to add Iceberg 🥬 to my shopping cart
+> I want to add Iceberg 🥬 to my shopping cart
+> I want to add Iceberg 🥬 to my shopping cart
+> I want to add Tomato  🍅 to my shopping cart
+> I want to add Chicken 🍗 to my shopping cart
+> I want to add Bread 🍞 to my shopping cart
+> I want to add Bread 🍞 to my shopping cart
+> I want to add Corn 🌽 to my shopping cart
+> I want to apply my coupon code PROMO_5
+> I want to see my shopping cart
+> ```
+
+```
+--------------------------------------------
+| Product name | Price with VAT | Quantity |
+| -----------  | -------------- | -------- |
+| Iceberg 🥬   | 2.17 €         | 3        |
+| Tomato  🍅   | 0.73 €         | 1        |
+| Chicken 🍗   | 1.83 €         | 1        |
+| Bread 🍞     | 0.88 €         | 2        |
+| Corn 🌽      | 1.50 €         | 1        |
+|------------------------------------------|
+| Promotion: 5% off with code PROMO_5      |
+--------------------------------------------
+| Total products: 8                        |
+| Total price: 11.71 €                     |
+--------------------------------------------
+```
+
+### Possible API for the ShoppingCart
+
+You could change this API this is only for example purposes.
+
+**Approach 1 passing objects as arguments could be DTO**
+
+```java
+public interface ShoppingCart {
+    public void addItem(Product product);
+    public void deleteItem(Product product);
+    public void applyDiscount(Discount discount)
+    public void printShoppingCart();
+}
+```
+
+**Approach 2 passing primitives as arguments**
+
+```java
+public interface ShoppingCart {
+    public void addItem(String productName);
+    public void deleteItem(String productName);
+    public void applyDiscount(Double discount)
+    public void printShoppingCart();
+}
+
+Approach 3 passing primitives as arguments and returning a DTO
+public interface ShoppingCart {
+    public void addItem(String productName);
+    public void deleteItem(String productName);
+    public void applyDiscount(Double discount)
+    public ShoppingCartList getShoppingCart();
+}
+```
+
+### Summary of steps
+
+**Inside-Out (classicist)** vs **Outside-In (London School / mockist)** has significant implications for how the system grows. Since I am aiming for **small, logical, test-driven steps**, I will start inside out.
+
+##### Suggested Inside-Out Iterations (with TDD focus)
+
+| Iteration | Focus                                    | Why Start Here?                              |
+| --------- | ---------------------------------------- | -------------------------------------------- |
+| 1         | `Product` - price per unit and VAT logic | Small, atomic, pure — perfect TDD start      |
+| 2         | `CartItem` - quantity & total price      | Introduces aggregation, still isolated logic |
+| 3         | `Discount` - percentage logic            | Stateless, predictable, complements pricing  |
+| 4         | `ShoppingCart` - add/remove items        | Start using composition of domain elements   |
+| 5         | `ShoppingCart` - apply discount          | Introduces first mutation to cart state      |
+| 6         | `ShoppingCart` - total price & print     | Drives end-to-end expectation-based testing  |
+| 7         | `ProductCatalogue` or Registry           | Encapsulate product lookup and validation    |
+
+### Evolution Flow Summary
+
+#### Phase 1: Pure Domain Logic
+
+- `Product` — validate markup/VAT/rounding rules
+- `CartItem` — quantity x price logic
+- `Discount` — test discount % and edge cases (e.g. invalid codes)
+
+#### Phase 2: Composition
+
+- `ShoppingCart` — manages cart items and uses the above types
+- Discounts applied as decorators or cart state
+
+#### Phase 3: Orchestration + I/O-style Outputs
+
+- Implement `ShoppingCart.getShoppingCart()` as DTO for rendering
+- `print()` or `toString()` as test-driving format rendering
+- Possibly inject or access product catalogue here
+
+### When to Consider *Outside-In*
+
+You could start Outside-In **only** if:
+
+- You’re driving everything from the end goal (like rendering the full cart view)
+- You're willing to mock deeper domain types (`Product`, `CartItem`, etc.)
+
+But in this kata, that’s harder to justify because the logic in the "leaf" types is richer and more test-worthy than in the orchestration layer.

From 6c8a63df3aa2f9cfea71e99ed78e668f13940102 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 13:49:08 +0100
Subject: [PATCH 02/29] Iteration1: Create failing test

---
 test-pnpm/shopping-cart-kata/product.should.test.ts | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 test-pnpm/shopping-cart-kata/product.should.test.ts

diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
new file mode 100644
index 0000000..ebc8c5e
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -0,0 +1,6 @@
+describe('Product should', () => {
+  it('calculate price per unit with revenue and rounding', () => {
+    const product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
+    expect(product.pricePerUnit).toBe(1.79);
+  });
+});

From c11d67ba4b36a7485b495841fee4f748de1a2ca7 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 14:06:26 +0100
Subject: [PATCH 03/29] Iteration1: Make test pass for a single product

---
 .../shopping-cart-kata/product.should.test.ts    |  4 +++-
 test-pnpm/shopping-cart-kata/product.ts          | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 test-pnpm/shopping-cart-kata/product.ts

diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index ebc8c5e..a10e7e6 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -1,6 +1,8 @@
+import { Product } from './product';
+
 describe('Product should', () => {
   it('calculate price per unit with revenue and rounding', () => {
-    const product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
+    const product = new Product('Iceberg 🥬', 1.55, 0.15);
     expect(product.pricePerUnit).toBe(1.79);
   });
 });
diff --git a/test-pnpm/shopping-cart-kata/product.ts b/test-pnpm/shopping-cart-kata/product.ts
new file mode 100644
index 0000000..bb65b8d
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/product.ts
@@ -0,0 +1,16 @@
+export class Product {
+  constructor(
+    public name: string,
+    public cost: number,
+    public revenueMargin: number,
+  ) {}
+
+  get pricePerUnit(): number {
+    const price = this.cost * (1 + this.revenueMargin);
+    return this.roundUp(price);
+  }
+
+  private roundUp(value: number): number {
+    return Math.ceil(value * 100) / 100;
+  }
+}

From 403e5c0ed040a0e64fc1f513c661235af87d0a43 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 14:18:06 +0100
Subject: [PATCH 04/29] Iteration1: Make test pass per unit  two products

---
 .../shopping-cart-kata/product.should.test.ts | 24 +++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index a10e7e6..0bb2870 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -1,8 +1,24 @@
 import { Product } from './product';
 
 describe('Product should', () => {
-  it('calculate price per unit with revenue and rounding', () => {
-    const product = new Product('Iceberg 🥬', 1.55, 0.15);
-    expect(product.pricePerUnit).toBe(1.79);
-  });
+  test.each([
+    {
+      name: 'Iceberg 🥬',
+      cost: 1.55,
+      revenueMargin: 0.15,
+      expected: 1.79,
+    },
+    {
+      name: 'Tomato 🍅',
+      cost: 2.5,
+      revenueMargin: 0.2,
+      expected: 3,
+    },
+  ])(
+    'calculate price per unit for $name to be $expected',
+    ({ name, cost, revenueMargin, expected }) => {
+      const product = new Product(name, cost, revenueMargin);
+      expect(product.pricePerUnit).toBe(expected);
+    },
+  );
 });

From c5a9f0d697cb3f9deea81511959a203f603f5733 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 14:25:28 +0100
Subject: [PATCH 05/29] Iteration1: Make test pass per unit for the rest

---
 .../shopping-cart-kata/product.should.test.ts | 24 ++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index 0bb2870..8bb81b3 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -10,9 +10,27 @@ describe('Product should', () => {
     },
     {
       name: 'Tomato 🍅',
-      cost: 2.5,
-      revenueMargin: 0.2,
-      expected: 3,
+      cost: 0.52,
+      revenueMargin: 0.15,
+      expected: 0.6,
+    },
+    {
+      name: 'Chicken 🍗',
+      cost: 1.34,
+      revenueMargin: 0.12,
+      expected: 1.51,
+    },
+    {
+      name: 'Bread 🍞',
+      cost: 0.71,
+      revenueMargin: 0.12,
+      expected: 0.8,
+    },
+    {
+      name: 'Corn 🌽',
+      cost: 1.21,
+      revenueMargin: 0.12,
+      expected: 1.36,
     },
   ])(
     'calculate price per unit for $name to be $expected',

From 3f925c03aa57616088cc3a9049c7dfef42e215df Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 14:29:17 +0100
Subject: [PATCH 06/29] Iteration1: Failing test for the final price

---
 test-pnpm/shopping-cart-kata/product.should.test.ts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index 8bb81b3..06ccd90 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -39,4 +39,9 @@ describe('Product should', () => {
       expect(product.pricePerUnit).toBe(expected);
     },
   );
+
+  it('calculate the final price with VAT rounded up', () => {
+    const product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
+    expect(product.finalPrice).toBe(2.17);
+  });
 });

From f8b75222c3a6323ed49b0facec3c132a16cdfcfc Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 22:07:09 +0100
Subject: [PATCH 07/29] Iteration1: Passing test for the final price with
 normal tax

---
 test-pnpm/shopping-cart-kata/TaxRate.ts             | 3 +++
 test-pnpm/shopping-cart-kata/product.should.test.ts | 3 ++-
 test-pnpm/shopping-cart-kata/product.ts             | 6 ++++++
 3 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 test-pnpm/shopping-cart-kata/TaxRate.ts

diff --git a/test-pnpm/shopping-cart-kata/TaxRate.ts b/test-pnpm/shopping-cart-kata/TaxRate.ts
new file mode 100644
index 0000000..1d8fcda
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/TaxRate.ts
@@ -0,0 +1,3 @@
+export enum TaxRate {
+  Normal = 0.21,
+}
diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index 06ccd90..3b6e69d 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -1,4 +1,5 @@
 import { Product } from './product';
+import { TaxRate } from './TaxRate';
 
 describe('Product should', () => {
   test.each([
@@ -40,7 +41,7 @@ describe('Product should', () => {
     },
   );
 
-  it('calculate the final price with VAT rounded up', () => {
+  it('calculate the final price with normal tax rounded up', () => {
     const product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
     expect(product.finalPrice).toBe(2.17);
   });
diff --git a/test-pnpm/shopping-cart-kata/product.ts b/test-pnpm/shopping-cart-kata/product.ts
index bb65b8d..719525f 100644
--- a/test-pnpm/shopping-cart-kata/product.ts
+++ b/test-pnpm/shopping-cart-kata/product.ts
@@ -3,6 +3,7 @@ export class Product {
     public name: string,
     public cost: number,
     public revenueMargin: number,
+    public taxRate: number = 0,
   ) {}
 
   get pricePerUnit(): number {
@@ -10,6 +11,11 @@ export class Product {
     return this.roundUp(price);
   }
 
+  get finalPrice(): number {
+    const price = this.pricePerUnit * (1 + this.taxRate);
+    return this.roundUp(price);
+  }
+
   private roundUp(value: number): number {
     return Math.ceil(value * 100) / 100;
   }

From c8a6f25bbec788a6a76f90db0d3c9e10a1400407 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 22:15:28 +0100
Subject: [PATCH 08/29] Iteration1: Passing test for the final price with first
 necessity tax

---
 test-pnpm/shopping-cart-kata/README.md              | 6 +++---
 test-pnpm/shopping-cart-kata/TaxRate.ts             | 1 +
 test-pnpm/shopping-cart-kata/product.should.test.ts | 7 ++++++-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/README.md b/test-pnpm/shopping-cart-kata/README.md
index 222b9bd..7ae1b1f 100644
--- a/test-pnpm/shopping-cart-kata/README.md
+++ b/test-pnpm/shopping-cart-kata/README.md
@@ -11,12 +11,12 @@ We are building a shopping cart for an online grocery shop. The idea of this kat
 
 ### List of products
 
-| **Name**   | **Cost** | **% Revenue** | **Price per unit** | **Tax**               | **Final price** |
-| ---------- | -------- | ------------- | ------------------ | --------------------- | --------------- |
+| **Name**  | **Cost** | **% Revenue** | **Price per unit** | **Tax**               | **Final price** |
+| --------- | -------- | ------------- | ------------------ | --------------------- | --------------- |
 | Iceberg 🥬 | 1.55 €   | 15 %          | 1,79 €             | Normal (21%)          | 2.17 €          |
 | Tomato 🍅  | 0.52 €   | 15 %          | 0.60 €             | Normal (21%)          | 0.73 €          |
 | Chicken 🍗 | 1.34 €   | 12 %          | 1.51 €             | Normal (21%)          | 1.83 €          |
-| Bread 🍞   | 0.71 €   | 12 %          | 0.80 €             | First necessity (10%) | 0.88 €          |
+| Bread 🍞   | 0.71 €   | 12 %          | 0.80 €             | First necessity (10%) | 0.89 €          |
 | Corn 🌽    | 1.21 €   | 12 %          | 1.36 €             | First necessity (10%) | 1.50 €          |
 
 ### List of discounts
diff --git a/test-pnpm/shopping-cart-kata/TaxRate.ts b/test-pnpm/shopping-cart-kata/TaxRate.ts
index 1d8fcda..42f84f8 100644
--- a/test-pnpm/shopping-cart-kata/TaxRate.ts
+++ b/test-pnpm/shopping-cart-kata/TaxRate.ts
@@ -1,3 +1,4 @@
 export enum TaxRate {
   Normal = 0.21,
+  FirstNecessity = 0.1,
 }
diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index 3b6e69d..a674e84 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -41,8 +41,13 @@ describe('Product should', () => {
     },
   );
 
-  it('calculate the final price with normal tax rounded up', () => {
+  it('calculate Iceberg 🥬 final price with normal vat rounded up', () => {
     const product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
     expect(product.finalPrice).toBe(2.17);
   });
+
+  it('calculate Bread 🍞 final price with first necessity vat rounded up', () => {
+    const product = new Product('Bread 🍞', 0.71, 0.12, TaxRate.FirstNecessity);
+    expect(product.finalPrice).toBe(0.89);
+  });
 });

From 880e6bae719842126e74808604fb3a9b0615b5d6 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sat, 3 May 2025 22:30:41 +0100
Subject: [PATCH 09/29] Iteration1: Full coverage

---
 .../shopping-cart-kata/product.should.test.ts | 52 +++++++++++++++----
 1 file changed, 43 insertions(+), 9 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index a674e84..ea743e8 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -41,13 +41,47 @@ describe('Product should', () => {
     },
   );
 
-  it('calculate Iceberg 🥬 final price with normal vat rounded up', () => {
-    const product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
-    expect(product.finalPrice).toBe(2.17);
-  });
-
-  it('calculate Bread 🍞 final price with first necessity vat rounded up', () => {
-    const product = new Product('Bread 🍞', 0.71, 0.12, TaxRate.FirstNecessity);
-    expect(product.finalPrice).toBe(0.89);
-  });
+  test.each([
+    {
+      name: 'Iceberg 🥬',
+      cost: 1.55,
+      revenueMargin: 0.15,
+      taxRate: TaxRate.Normal,
+      expected: 2.17,
+    },
+    {
+      name: 'Tomato 🍅',
+      cost: 0.52,
+      revenueMargin: 0.15,
+      taxRate: TaxRate.Normal,
+      expected: 0.73,
+    },
+    {
+      name: 'Chicken 🍗',
+      cost: 1.34,
+      revenueMargin: 0.12,
+      taxRate: TaxRate.Normal,
+      expected: 1.83,
+    },
+    {
+      name: 'Bread 🍞',
+      cost: 0.71,
+      revenueMargin: 0.12,
+      taxRate: TaxRate.FirstNecessity,
+      expected: 0.89,
+    },
+    {
+      name: 'Corn 🌽',
+      cost: 1.21,
+      revenueMargin: 0.12,
+      taxRate: TaxRate.FirstNecessity,
+      expected: 1.5,
+    },
+  ])(
+    'calculate final price unit for $name to be $expected for vat rate @ $taxRate',
+    ({ name, cost, revenueMargin, taxRate, expected }) => {
+      const product = new Product(name, cost, revenueMargin, taxRate);
+      expect(product.finalPrice).toBe(expected);
+    },
+  );
 });

From 18b4da69434d79d236d8693b3206e2a8ec140bb0 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sun, 4 May 2025 14:24:21 +0100
Subject: [PATCH 10/29] Iteration2: Create failing test for cart item

---
 test-pnpm/shopping-cart-kata/cartitem.should.test.ts | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 test-pnpm/shopping-cart-kata/cartitem.should.test.ts

diff --git a/test-pnpm/shopping-cart-kata/cartitem.should.test.ts b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
new file mode 100644
index 0000000..6d1fb67
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
@@ -0,0 +1,12 @@
+import { Product } from './product';
+import { TaxRate } from './TaxRate';
+
+describe('Adding Cart items should', () => {
+  let product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
+  test('calcultate the line total for one item', () => {
+    const cartItem = new CartItem(product, 1);
+    const expected = 2.17;
+
+    expect(cartItem.LineTotal).toBe(expected);
+  });
+});

From ebce475171f0e938ae1834e88bdd4b1e89b60e14 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sun, 4 May 2025 14:34:58 +0100
Subject: [PATCH 11/29] Iteration2: Make test pass for single item

---
 test-pnpm/shopping-cart-kata/cartItem.ts        | 17 +++++++++++++++++
 .../shopping-cart-kata/cartitem.should.test.ts  |  1 +
 2 files changed, 18 insertions(+)
 create mode 100644 test-pnpm/shopping-cart-kata/cartItem.ts

diff --git a/test-pnpm/shopping-cart-kata/cartItem.ts b/test-pnpm/shopping-cart-kata/cartItem.ts
new file mode 100644
index 0000000..cbf22e8
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/cartItem.ts
@@ -0,0 +1,17 @@
+import { Product } from './product';
+
+export class CartItem {
+  constructor(
+    public product: Product,
+    public quantity: number,
+  ) {}
+
+  get LineTotal(): number {
+    const price = this.product.finalPrice * this.quantity;
+    return this.roundUp(price);
+  }
+
+  private roundUp(value: number): number {
+    return Math.ceil(value * 100) / 100;
+  }
+}
diff --git a/test-pnpm/shopping-cart-kata/cartitem.should.test.ts b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
index 6d1fb67..0ecb5cb 100644
--- a/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
@@ -1,3 +1,4 @@
+import { CartItem } from './cartItem';
 import { Product } from './product';
 import { TaxRate } from './TaxRate';
 

From 3046c362231db77d8d00e8eb3ce180021caed818 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sun, 4 May 2025 14:37:12 +0100
Subject: [PATCH 12/29] Iteration2: Make test pass for multiple  items

---
 test-pnpm/shopping-cart-kata/cartitem.should.test.ts | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/cartitem.should.test.ts b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
index 0ecb5cb..e7a58bd 100644
--- a/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
@@ -4,10 +4,16 @@ import { TaxRate } from './TaxRate';
 
 describe('Adding Cart items should', () => {
   let product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
+  
   test('calcultate the line total for one item', () => {
     const cartItem = new CartItem(product, 1);
-    const expected = 2.17;
 
-    expect(cartItem.LineTotal).toBe(expected);
+    expect(cartItem.LineTotal).toBe(2.17);
+  });
+
+  test('calcultate the line total for multiple items', () => {
+    const cartItem = new CartItem(product, 3);
+
+    expect(cartItem.LineTotal).toBe(6.51);
   });
 });

From 113132cccee2137d52d54615b71cc7f827068903 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Sun, 4 May 2025 23:26:36 +0100
Subject: [PATCH 13/29] Iteration2: Minor refactor - Duplication removal
 Filename taxRate.ts

---
 test-pnpm/shopping-cart-kata/cartItem.ts               |  7 ++-----
 test-pnpm/shopping-cart-kata/cartitem.should.test.ts   |  2 +-
 test-pnpm/shopping-cart-kata/product.should.test.ts    |  2 +-
 test-pnpm/shopping-cart-kata/product.ts                | 10 ++++------
 .../shopping-cart-kata/{TaxRate.ts => taxRates.ts}     |  0
 test-pnpm/shopping-cart-kata/utility.ts                |  3 +++
 6 files changed, 11 insertions(+), 13 deletions(-)
 rename test-pnpm/shopping-cart-kata/{TaxRate.ts => taxRates.ts} (100%)
 create mode 100644 test-pnpm/shopping-cart-kata/utility.ts

diff --git a/test-pnpm/shopping-cart-kata/cartItem.ts b/test-pnpm/shopping-cart-kata/cartItem.ts
index cbf22e8..c6a1588 100644
--- a/test-pnpm/shopping-cart-kata/cartItem.ts
+++ b/test-pnpm/shopping-cart-kata/cartItem.ts
@@ -1,4 +1,5 @@
 import { Product } from './product';
+import { roundUp } from './utility';
 
 export class CartItem {
   constructor(
@@ -8,10 +9,6 @@ export class CartItem {
 
   get LineTotal(): number {
     const price = this.product.finalPrice * this.quantity;
-    return this.roundUp(price);
-  }
-
-  private roundUp(value: number): number {
-    return Math.ceil(value * 100) / 100;
+    return roundUp(price);
   }
 }
diff --git a/test-pnpm/shopping-cart-kata/cartitem.should.test.ts b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
index e7a58bd..8cce6fb 100644
--- a/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/cartitem.should.test.ts
@@ -1,6 +1,6 @@
 import { CartItem } from './cartItem';
 import { Product } from './product';
-import { TaxRate } from './TaxRate';
+import { TaxRate } from './taxRates';
 
 describe('Adding Cart items should', () => {
   let product = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
diff --git a/test-pnpm/shopping-cart-kata/product.should.test.ts b/test-pnpm/shopping-cart-kata/product.should.test.ts
index ea743e8..294c94f 100644
--- a/test-pnpm/shopping-cart-kata/product.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/product.should.test.ts
@@ -1,5 +1,5 @@
 import { Product } from './product';
-import { TaxRate } from './TaxRate';
+import { TaxRate } from './taxRates';
 
 describe('Product should', () => {
   test.each([
diff --git a/test-pnpm/shopping-cart-kata/product.ts b/test-pnpm/shopping-cart-kata/product.ts
index 719525f..4884bbe 100644
--- a/test-pnpm/shopping-cart-kata/product.ts
+++ b/test-pnpm/shopping-cart-kata/product.ts
@@ -1,3 +1,5 @@
+import { roundUp } from './utility';
+
 export class Product {
   constructor(
     public name: string,
@@ -8,15 +10,11 @@ export class Product {
 
   get pricePerUnit(): number {
     const price = this.cost * (1 + this.revenueMargin);
-    return this.roundUp(price);
+    return roundUp(price);
   }
 
   get finalPrice(): number {
     const price = this.pricePerUnit * (1 + this.taxRate);
-    return this.roundUp(price);
-  }
-
-  private roundUp(value: number): number {
-    return Math.ceil(value * 100) / 100;
+    return roundUp(price);
   }
 }
diff --git a/test-pnpm/shopping-cart-kata/TaxRate.ts b/test-pnpm/shopping-cart-kata/taxRates.ts
similarity index 100%
rename from test-pnpm/shopping-cart-kata/TaxRate.ts
rename to test-pnpm/shopping-cart-kata/taxRates.ts
diff --git a/test-pnpm/shopping-cart-kata/utility.ts b/test-pnpm/shopping-cart-kata/utility.ts
new file mode 100644
index 0000000..9a5c375
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/utility.ts
@@ -0,0 +1,3 @@
+export function roundUp(value: number): number {
+  return Math.ceil(value * 100) / 100;
+}

From 8ca7cbf76b46afa09e721918c6177dcabbefd130 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Mon, 5 May 2025 00:23:34 +0100
Subject: [PATCH 14/29] Iteration3: Failing test for creating a discount

---
 test-pnpm/shopping-cart-kata/discount.should.test.ts | 7 +++++++
 1 file changed, 7 insertions(+)
 create mode 100644 test-pnpm/shopping-cart-kata/discount.should.test.ts

diff --git a/test-pnpm/shopping-cart-kata/discount.should.test.ts b/test-pnpm/shopping-cart-kata/discount.should.test.ts
new file mode 100644
index 0000000..d27b95c
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/discount.should.test.ts
@@ -0,0 +1,7 @@
+describe('Discount should', () => {
+  it('be created from a valid discount code', () => {
+    const discount = Discount.fromCode('PROMO_5');
+    expect(discount.code).toBe('PROMO_5');
+    expect(discount.percentage).toBe(0.05);
+  });
+});

From 6f2d4af984ae7b4b98e00b2c26c76d6793334212 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Mon, 5 May 2025 00:34:41 +0100
Subject: [PATCH 15/29] Iteration3: Make simple promo pass

---
 .../shopping-cart-kata/discount.should.test.ts  |  3 +++
 test-pnpm/shopping-cart-kata/discount.ts        | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 test-pnpm/shopping-cart-kata/discount.ts

diff --git a/test-pnpm/shopping-cart-kata/discount.should.test.ts b/test-pnpm/shopping-cart-kata/discount.should.test.ts
index d27b95c..d9ba246 100644
--- a/test-pnpm/shopping-cart-kata/discount.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/discount.should.test.ts
@@ -1,6 +1,9 @@
+import { Discount } from './discount';
+
 describe('Discount should', () => {
   it('be created from a valid discount code', () => {
     const discount = Discount.fromCode('PROMO_5');
+
     expect(discount.code).toBe('PROMO_5');
     expect(discount.percentage).toBe(0.05);
   });
diff --git a/test-pnpm/shopping-cart-kata/discount.ts b/test-pnpm/shopping-cart-kata/discount.ts
new file mode 100644
index 0000000..12ce93a
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/discount.ts
@@ -0,0 +1,17 @@
+export class Discount {
+  readonly code: string;
+  readonly percentage: number;
+
+  private constructor(code: string, percentage: number) {
+    this.code = code;
+    this.percentage = percentage;
+  }
+
+  static fromCode(code: string): Discount | null {
+    const map: Record<string, number> = {
+      PROMO_5: 0.05,
+    };
+    const value = map[code];
+    return new Discount(code, value);
+  }
+}

From d2edc1524ac627feed6a3de04f522b123d741b38 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Mon, 5 May 2025 00:35:52 +0100
Subject: [PATCH 16/29] Iteration3: Failing test for unknown promocode

---
 test-pnpm/shopping-cart-kata/discount.should.test.ts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/test-pnpm/shopping-cart-kata/discount.should.test.ts b/test-pnpm/shopping-cart-kata/discount.should.test.ts
index d9ba246..4f8de15 100644
--- a/test-pnpm/shopping-cart-kata/discount.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/discount.should.test.ts
@@ -7,4 +7,9 @@ describe('Discount should', () => {
     expect(discount.code).toBe('PROMO_5');
     expect(discount.percentage).toBe(0.05);
   });
+
+  it('return null for an unknown code', () => {
+    const discount = Discount.fromCode('INVALID');
+    expect(discount).toBeNull();
+  });
 });

From f4648270d2abd05b523c47a1707f6f3d96ccc641 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Mon, 5 May 2025 00:43:32 +0100
Subject: [PATCH 17/29] Iteration3: Fix null discount for unknown discount code

---
 test-pnpm/shopping-cart-kata/discount.should.test.ts | 1 +
 test-pnpm/shopping-cart-kata/discount.ts             | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/test-pnpm/shopping-cart-kata/discount.should.test.ts b/test-pnpm/shopping-cart-kata/discount.should.test.ts
index 4f8de15..2437ee6 100644
--- a/test-pnpm/shopping-cart-kata/discount.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/discount.should.test.ts
@@ -10,6 +10,7 @@ describe('Discount should', () => {
 
   it('return null for an unknown code', () => {
     const discount = Discount.fromCode('INVALID');
+
     expect(discount).toBeNull();
   });
 });
diff --git a/test-pnpm/shopping-cart-kata/discount.ts b/test-pnpm/shopping-cart-kata/discount.ts
index 12ce93a..c9e4bcc 100644
--- a/test-pnpm/shopping-cart-kata/discount.ts
+++ b/test-pnpm/shopping-cart-kata/discount.ts
@@ -12,6 +12,6 @@ export class Discount {
       PROMO_5: 0.05,
     };
     const value = map[code];
-    return new Discount(code, value);
+    return value ? new Discount(code, value) : null;
   }
 }

From 294ab3204a01d807fff109fd54826de7b345048a Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Mon, 5 May 2025 00:46:24 +0100
Subject: [PATCH 18/29] Iteration3: Failing test for applying a 10% discount

---
 test-pnpm/shopping-cart-kata/discount.should.test.ts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/test-pnpm/shopping-cart-kata/discount.should.test.ts b/test-pnpm/shopping-cart-kata/discount.should.test.ts
index 2437ee6..54aea3b 100644
--- a/test-pnpm/shopping-cart-kata/discount.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/discount.should.test.ts
@@ -13,4 +13,9 @@ describe('Discount should', () => {
 
     expect(discount).toBeNull();
   });
+
+  it('alculate a discount from a price', () => {
+    const discount = Discount.fromCode('PROMO_10')!;
+    expect(discount.applyTo(100)).toBe(90);
+  });
 });

From 75793831cf4c9010e804c068a578f85975999710 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Mon, 5 May 2025 00:55:00 +0100
Subject: [PATCH 19/29] Iteration3: Fix the method to apply discounts rounding
 up

---
 test-pnpm/shopping-cart-kata/discount.ts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/test-pnpm/shopping-cart-kata/discount.ts b/test-pnpm/shopping-cart-kata/discount.ts
index c9e4bcc..247c95c 100644
--- a/test-pnpm/shopping-cart-kata/discount.ts
+++ b/test-pnpm/shopping-cart-kata/discount.ts
@@ -1,3 +1,5 @@
+import { roundUp } from './utility';
+
 export class Discount {
   readonly code: string;
   readonly percentage: number;
@@ -7,9 +9,16 @@ export class Discount {
     this.percentage = percentage;
   }
 
+  public applyTo(price: number): number {
+    const discountAmount = price * this.percentage;
+    const discountedPrice = price - discountAmount;
+    return roundUp(discountedPrice);
+  }
+
   static fromCode(code: string): Discount | null {
     const map: Record<string, number> = {
       PROMO_5: 0.05,
+      PROMO_10: 0.1,
     };
     const value = map[code];
     return value ? new Discount(code, value) : null;

From e1c72da0d63dfe37ba8a477beba14ffcbf7d52bd Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 09:58:46 +0100
Subject: [PATCH 20/29] Iteration4: Creted failing test for adding items to the
 shopping cart Add a shoping cart interface with the expected interface

---
 test-pnpm/shopping-cart-kata/README.md        | 42 +++++++++----------
 test-pnpm/shopping-cart-kata/shoppingCart.ts  |  9 ++++
 .../shoppingcart.should.test.ts               | 40 ++++++++++++++++++
 3 files changed, 70 insertions(+), 21 deletions(-)
 create mode 100644 test-pnpm/shopping-cart-kata/shoppingCart.ts
 create mode 100644 test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts

diff --git a/test-pnpm/shopping-cart-kata/README.md b/test-pnpm/shopping-cart-kata/README.md
index 7ae1b1f..bb8d54a 100644
--- a/test-pnpm/shopping-cart-kata/README.md
+++ b/test-pnpm/shopping-cart-kata/README.md
@@ -11,20 +11,20 @@ We are building a shopping cart for an online grocery shop. The idea of this kat
 
 ### List of products
 
-| **Name**  | **Cost** | **% Revenue** | **Price per unit** | **Tax**               | **Final price** |
-| --------- | -------- | ------------- | ------------------ | --------------------- | --------------- |
-| Iceberg 🥬 | 1.55 €   | 15 %          | 1,79 €             | Normal (21%)          | 2.17 €          |
-| Tomato 🍅  | 0.52 €   | 15 %          | 0.60 €             | Normal (21%)          | 0.73 €          |
-| Chicken 🍗 | 1.34 €   | 12 %          | 1.51 €             | Normal (21%)          | 1.83 €          |
-| Bread 🍞   | 0.71 €   | 12 %          | 0.80 €             | First necessity (10%) | 0.89 €          |
-| Corn 🌽    | 1.21 €   | 12 %          | 1.36 €             | First necessity (10%) | 1.50 €          |
+| **Name**      | **Cost** | **% Revenue** | **Price per unit** | **Tax**                 | **Final price** |
+| ------------- | -------- | ------------- | ------------------ | ----------------------- | --------------- |
+| **Iceberg 🥬** | *1.55 €* | *15 %*        | 1,79 €             | *Normal (21%)*          | 2.17 €          |
+| **Tomato 🍅**  | *0.52 €* | *15 %*        | 0.60 €             | *Normal (21%)*          | 0.73 €          |
+| **Chicken 🍗** | *1.34 €* | *12 %*        | 1.51 €             | *Normal (21%)*          | 1.83 €          |
+| **Bread 🍞**   | *0.71 €* | *12 %*        | 0.80 €             | *First necessity (10%)* | 0.89 €          |
+| **Corn 🌽**    | *1.21 €* | *12 %*        | 1.36 €             | *First necessity (10%)* | 1.50 €          |
 
 ### List of discounts
 
 | **Discounts code** | **Amount** |
 | :----------------: | ---------- |
-|      PROMO_5       | 5%         |
-|      PROMO_10      | 10%        |
+|    **PROMO_5**     | 5%         |
+|    **PROMO_10**    | 10%        |
 
 ### Use cases
 
@@ -149,23 +149,23 @@ You could change this API this is only for example purposes.
 
 **Approach 1 passing objects as arguments could be DTO**
 
-```java
-public interface ShoppingCart {
-    public void addItem(Product product);
-    public void deleteItem(Product product);
-    public void applyDiscount(Discount discount)
-    public void printShoppingCart();
+```javascript
+export interface ShoppingCart {
+  addItem(product: Product): void;
+  deleteItem(product: Product): void;
+  applyDiscount(discount: Discount): void;
+  printShoppingCart(): void;
 }
 ```
 
 **Approach 2 passing primitives as arguments**
 
-```java
-public interface ShoppingCart {
-    public void addItem(String productName);
-    public void deleteItem(String productName);
-    public void applyDiscount(Double discount)
-    public void printShoppingCart();
+```javascript
+export interface ShoppingCart {
+  addItem(cartItem: CartItem): void;
+  deleteItem(cartItem: CartItem): void;
+  applyDiscount(discount: Discount): void;
+  printShoppingCart(): void;
 }
 
 Approach 3 passing primitives as arguments and returning a DTO
diff --git a/test-pnpm/shopping-cart-kata/shoppingCart.ts b/test-pnpm/shopping-cart-kata/shoppingCart.ts
new file mode 100644
index 0000000..8851549
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/shoppingCart.ts
@@ -0,0 +1,9 @@
+import { Discount } from './discount';
+import { Product } from './product';
+
+export interface ShoppingCart {
+  addItem(product: Product): void;
+  deleteItem(product: Product): void;
+  applyDiscount(discount: Discount): void;
+  printShoppingCart(): void;
+}
diff --git a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
new file mode 100644
index 0000000..5a35e5f
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
@@ -0,0 +1,40 @@
+import { CartItem } from './cartItem';
+import { InMemoryLogger } from './logger';
+import { Product } from './product';
+import { InMemoryShoppingCart } from './shoppingCart';
+import { TaxRate } from './taxRates';
+
+describe('As a customer', () => {
+  const iceberg = new Product('Iceberg 🥬', 1.55, 0.15, TaxRate.Normal);
+  const tomato = new Product('Tomato 🍅', 0.52, 0.15, TaxRate.Normal);
+  const chicken = new Product('Chicken 🍗', 1.34, 0.12, TaxRate.Normal);
+  const bread = new Product('Bread 🍞', 0.71, 0.12, TaxRate.FirstNecessity);
+  const corn = new Product('Corn 🌽', 1.21, 0.12, TaxRate.FirstNecessity);
+
+  function addItemsToCart(cart: InMemoryShoppingCart) {
+    cart.addItem(new CartItem(iceberg, 3));
+    cart.addItem(new CartItem(tomato, 1));
+    cart.addItem(new CartItem(chicken, 1));
+    cart.addItem(new CartItem(bread, 2));
+    cart.addItem(new CartItem(corn, 1));
+  }
+
+  test('I want to add items to my shopping cart', () => {
+    const logger = new InMemoryLogger();
+    const cart = new InMemoryShoppingCart(logger);
+    addItemsToCart(cart);
+
+    const expectedOutput = [
+      '--------------------------------------------',
+      '| Product name | Price with VAT | Quantity |',
+      '| ------------ | -------------- | -------- |',
+      '| Iceberg 🥬   | 2.17 €         | 3        |',
+      '| Tomato 🍅    | 0.73 €         | 1        |',
+      '| Chicken 🍗   | 1.83 €         | 1        |',
+      '| Bread 🍞     | 0.89 €         | 2        |',
+      '| Corn 🌽      | 1.50 €         | 1        |',
+    ].join('\n');
+
+    expect(logger.print()).toContain(expectedOutput);
+  });
+});

From 53176b56963a51d20379afaaf036d7d5cd5425a7 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 12:54:55 +0100
Subject: [PATCH 21/29] Iteration4: Make test pass with the header, line items

---
 test-pnpm/shopping-cart-kata/logger.ts       | 16 +++++++++++
 test-pnpm/shopping-cart-kata/printer.ts      | 29 ++++++++++++++++++++
 test-pnpm/shopping-cart-kata/shoppingCart.ts | 29 ++++++++++++++++++--
 3 files changed, 71 insertions(+), 3 deletions(-)
 create mode 100644 test-pnpm/shopping-cart-kata/logger.ts
 create mode 100644 test-pnpm/shopping-cart-kata/printer.ts

diff --git a/test-pnpm/shopping-cart-kata/logger.ts b/test-pnpm/shopping-cart-kata/logger.ts
new file mode 100644
index 0000000..46007e7
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/logger.ts
@@ -0,0 +1,16 @@
+export interface Logger {
+  log(message: string): void;
+  print(): string;
+}
+
+export class InMemoryLogger implements Logger {
+  private messages: string[] = [];
+
+  log(message: string): void {
+    this.messages.push(message);
+  }
+
+  print(): string {
+    return this.messages.join('\n');
+  }
+}
diff --git a/test-pnpm/shopping-cart-kata/printer.ts b/test-pnpm/shopping-cart-kata/printer.ts
new file mode 100644
index 0000000..521de22
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/printer.ts
@@ -0,0 +1,29 @@
+import { CartItem } from './cartItem';
+
+export interface TablePrinter {
+  printHeader(): string;
+  printCartItem(item: CartItem): string;
+  printLineSeparator(): string;
+}
+
+export class InMemoryTablePrinter implements TablePrinter {
+  printHeader(): string {
+    return [
+      '--------------------------------------------',
+      '| Product name | Price with VAT | Quantity |',
+      '| ------------ | -------------- | -------- |',
+    ].join('\n');
+  }
+
+  printCartItem(item: CartItem): string {
+    const name = item.product.name.padEnd(12);
+    const priceWithVat = `${item.product.finalPrice.toFixed(2)} €`.padEnd(14);
+    const quantity = item.quantity.toString().padEnd(8);
+
+    return `| ${name} | ${priceWithVat} | ${quantity} |`;
+  }
+
+  printLineSeparator(): string {
+    return '--------------------------------------------';
+  }
+}
diff --git a/test-pnpm/shopping-cart-kata/shoppingCart.ts b/test-pnpm/shopping-cart-kata/shoppingCart.ts
index 8851549..2323a30 100644
--- a/test-pnpm/shopping-cart-kata/shoppingCart.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingCart.ts
@@ -1,9 +1,32 @@
+import { CartItem } from './cartItem';
 import { Discount } from './discount';
-import { Product } from './product';
+import { Logger } from './logger';
+import { InMemoryTablePrinter, TablePrinter } from './printer';
 
 export interface ShoppingCart {
-  addItem(product: Product): void;
-  deleteItem(product: Product): void;
+  addItem(cartItem: CartItem): void;
   applyDiscount(discount: Discount): void;
   printShoppingCart(): void;
 }
+
+export class InMemoryShoppingCart implements ShoppingCart {
+  private items: CartItem[] = [];
+  private discounts: Discount[] = [];
+  private printer: TablePrinter = new InMemoryTablePrinter();
+
+  constructor(private logger: Logger) {
+    this.logger.log(this.printer.printHeader());
+  }
+
+  addItem(cartItem: CartItem): void {
+    this.items.push(cartItem);
+    this.logger.log(this.printer.printCartItem(cartItem));
+  }
+
+  applyDiscount(discount: Discount): void {
+    throw new Error('Method not implemented.');
+  }
+  printShoppingCart(): void {
+    throw new Error('Method not implemented.');
+  }
+}

From 6970df79cb74b801e83bffb0e0bbc5d0eca80e87 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 16:41:22 +0100
Subject: [PATCH 22/29] Iteration5: Add promotion fail test scenarios

---
 test-pnpm/shopping-cart-kata/README.md        |  2 +-
 .../shoppingcart.should.test.ts               | 35 +++++++++++++++++--
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/README.md b/test-pnpm/shopping-cart-kata/README.md
index bb8d54a..d761ee8 100644
--- a/test-pnpm/shopping-cart-kata/README.md
+++ b/test-pnpm/shopping-cart-kata/README.md
@@ -145,7 +145,7 @@ We are building a shopping cart for an online grocery shop. The idea of this kat
 
 ### Possible API for the ShoppingCart
 
-You could change this API this is only for example purposes.
+You could change this API, this is only for example purposes.
 
 **Approach 1 passing objects as arguments could be DTO**
 
diff --git a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
index 5a35e5f..829791d 100644
--- a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
@@ -1,4 +1,5 @@
 import { CartItem } from './cartItem';
+import { Discount } from './discount';
 import { InMemoryLogger } from './logger';
 import { Product } from './product';
 import { InMemoryShoppingCart } from './shoppingCart';
@@ -22,8 +23,6 @@ describe('As a customer', () => {
   test('I want to add items to my shopping cart', () => {
     const logger = new InMemoryLogger();
     const cart = new InMemoryShoppingCart(logger);
-    addItemsToCart(cart);
-
     const expectedOutput = [
       '--------------------------------------------',
       '| Product name | Price with VAT | Quantity |',
@@ -35,6 +34,38 @@ describe('As a customer', () => {
       '| Corn 🌽      | 1.50 €         | 1        |',
     ].join('\n');
 
+    addItemsToCart(cart);
+
+    expect(logger.print()).toContain(expectedOutput);
+  });
+
+  test('I want to create a promotion section for no promotions', () => {
+    const logger = new InMemoryLogger();
+    const cart = new InMemoryShoppingCart(logger);
+    addItemsToCart(cart);
+    const expectedOutput = [
+      '|------------------------------------------|',
+      '| Promotion:                               |',
+      '--------------------------------------------',
+    ].join('\n');
+
+    cart.applyDiscount(null);
+
+    expect(logger.print()).toContain(expectedOutput);
+  });
+
+  test('I want to create a promotion section for an actual promotion', () => {
+    const logger = new InMemoryLogger();
+    const cart = new InMemoryShoppingCart(logger);
+    addItemsToCart(cart);
+    const expectedOutput = [
+      '|------------------------------------------|',
+      '| Promotion: 10% off with code PROMO_10    |',
+      '--------------------------------------------',
+    ].join('\n');
+
+    cart.applyDiscount(Discount.fromCode('PROMO_10'));
+
     expect(logger.print()).toContain(expectedOutput);
   });
 });

From 7132291fac6e2d059c9492c17889313706e2d136 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 16:41:44 +0100
Subject: [PATCH 23/29] Iteration5: Make tests pass

---
 test-pnpm/shopping-cart-kata/printer.ts      | 16 ++++++++++++++++
 test-pnpm/shopping-cart-kata/shoppingCart.ts |  6 ++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/printer.ts b/test-pnpm/shopping-cart-kata/printer.ts
index 521de22..b13722d 100644
--- a/test-pnpm/shopping-cart-kata/printer.ts
+++ b/test-pnpm/shopping-cart-kata/printer.ts
@@ -1,9 +1,12 @@
 import { CartItem } from './cartItem';
+import { Discount } from './discount';
 
 export interface TablePrinter {
   printHeader(): string;
   printCartItem(item: CartItem): string;
+  printPromotion(discount: Discount | null): string;
   printLineSeparator(): string;
+  printHeaderFooter(): string;
 }
 
 export class InMemoryTablePrinter implements TablePrinter {
@@ -15,6 +18,10 @@ export class InMemoryTablePrinter implements TablePrinter {
     ].join('\n');
   }
 
+  printHeaderFooter(): string {
+    return '|------------------------------------------|';
+  }
+
   printCartItem(item: CartItem): string {
     const name = item.product.name.padEnd(12);
     const priceWithVat = `${item.product.finalPrice.toFixed(2)} €`.padEnd(14);
@@ -26,4 +33,13 @@ export class InMemoryTablePrinter implements TablePrinter {
   printLineSeparator(): string {
     return '--------------------------------------------';
   }
+
+  printPromotion(discount: Discount | null): string {
+    const promotionCode = discount?.code ?? '';
+    const promotionDescription =
+      discount != null
+        ? `Promotion: ${discount?.percentage * 100}% off with code ${promotionCode}`
+        : 'Promotion:';
+    return [this.printHeaderFooter(), `| ${promotionDescription.padEnd(40)} |`].join('\n');
+  }
 }
diff --git a/test-pnpm/shopping-cart-kata/shoppingCart.ts b/test-pnpm/shopping-cart-kata/shoppingCart.ts
index 2323a30..a0e8ed7 100644
--- a/test-pnpm/shopping-cart-kata/shoppingCart.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingCart.ts
@@ -23,8 +23,10 @@ export class InMemoryShoppingCart implements ShoppingCart {
     this.logger.log(this.printer.printCartItem(cartItem));
   }
 
-  applyDiscount(discount: Discount): void {
-    throw new Error('Method not implemented.');
+  applyDiscount(discount: Discount | null): void {
+    this.discounts.push(discount);
+    this.logger.log(this.printer.printPromotion(discount));
+    this.logger.log(this.printer.printLineSeparator());
   }
   printShoppingCart(): void {
     throw new Error('Method not implemented.');

From cfb23b4aea57c612461e95756a2a66b6513b57fc Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 17:36:15 +0100
Subject: [PATCH 24/29] Iteration5: Minor refactor to make sure printing order
 and simplicity maintained

---
 test-pnpm/shopping-cart-kata/README.md        | 21 ------------
 test-pnpm/shopping-cart-kata/logger.ts        | 11 +++++-
 test-pnpm/shopping-cart-kata/shoppingCart.ts  | 34 ++++++++++++++-----
 .../shoppingcart.should.test.ts               |  4 ++-
 4 files changed, 39 insertions(+), 31 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/README.md b/test-pnpm/shopping-cart-kata/README.md
index d761ee8..b95ebc0 100644
--- a/test-pnpm/shopping-cart-kata/README.md
+++ b/test-pnpm/shopping-cart-kata/README.md
@@ -145,21 +145,8 @@ We are building a shopping cart for an online grocery shop. The idea of this kat
 
 ### Possible API for the ShoppingCart
 
-You could change this API, this is only for example purposes.
-
 **Approach 1 passing objects as arguments could be DTO**
 
-```javascript
-export interface ShoppingCart {
-  addItem(product: Product): void;
-  deleteItem(product: Product): void;
-  applyDiscount(discount: Discount): void;
-  printShoppingCart(): void;
-}
-```
-
-**Approach 2 passing primitives as arguments**
-
 ```javascript
 export interface ShoppingCart {
   addItem(cartItem: CartItem): void;
@@ -167,14 +154,6 @@ export interface ShoppingCart {
   applyDiscount(discount: Discount): void;
   printShoppingCart(): void;
 }
-
-Approach 3 passing primitives as arguments and returning a DTO
-public interface ShoppingCart {
-    public void addItem(String productName);
-    public void deleteItem(String productName);
-    public void applyDiscount(Double discount)
-    public ShoppingCartList getShoppingCart();
-}
 ```
 
 ### Summary of steps
diff --git a/test-pnpm/shopping-cart-kata/logger.ts b/test-pnpm/shopping-cart-kata/logger.ts
index 46007e7..c6985b2 100644
--- a/test-pnpm/shopping-cart-kata/logger.ts
+++ b/test-pnpm/shopping-cart-kata/logger.ts
@@ -1,10 +1,19 @@
 export interface Logger {
   log(message: string): void;
   print(): string;
+  clear(): void;
 }
 
 export class InMemoryLogger implements Logger {
-  private messages: string[] = [];
+  private messages: string[];
+
+  constructor() {
+    this.clear();
+  }
+
+  clear(): void {
+    this.messages = [];
+  }
 
   log(message: string): void {
     this.messages.push(message);
diff --git a/test-pnpm/shopping-cart-kata/shoppingCart.ts b/test-pnpm/shopping-cart-kata/shoppingCart.ts
index a0e8ed7..c75a7ac 100644
--- a/test-pnpm/shopping-cart-kata/shoppingCart.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingCart.ts
@@ -14,21 +14,39 @@ export class InMemoryShoppingCart implements ShoppingCart {
   private discounts: Discount[] = [];
   private printer: TablePrinter = new InMemoryTablePrinter();
 
-  constructor(private logger: Logger) {
-    this.logger.log(this.printer.printHeader());
-  }
+  constructor(private logger: Logger) {}
 
   addItem(cartItem: CartItem): void {
     this.items.push(cartItem);
-    this.logger.log(this.printer.printCartItem(cartItem));
   }
 
   applyDiscount(discount: Discount | null): void {
-    this.discounts.push(discount);
-    this.logger.log(this.printer.printPromotion(discount));
-    this.logger.log(this.printer.printLineSeparator());
+    if (discount) {
+      this.discounts.push(discount);
+    }
   }
+
   printShoppingCart(): void {
-    throw new Error('Method not implemented.');
+    this.logger.clear();
+    this.printCartItems();
+    this.printDiscounts();
+  }
+
+  private printCartItems(): void {
+    this.logger.log(this.printer.printHeader());
+    this.items.forEach((cartItem) => {
+      this.logger.log(this.printer.printCartItem(cartItem));
+    });
+  }
+
+  private printDiscounts(): void {
+    if (this.discounts.length > 0) {
+      this.discounts.forEach((discount) => {
+        this.logger.log(this.printer.printPromotion(discount));
+      });
+    } else {
+      this.logger.log(this.printer.printPromotion(null));
+    }
+    this.logger.log(this.printer.printLineSeparator());
   }
 }
diff --git a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
index 829791d..5e91b35 100644
--- a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
@@ -36,6 +36,7 @@ describe('As a customer', () => {
 
     addItemsToCart(cart);
 
+    cart.printShoppingCart();
     expect(logger.print()).toContain(expectedOutput);
   });
 
@@ -49,7 +50,7 @@ describe('As a customer', () => {
       '--------------------------------------------',
     ].join('\n');
 
-    cart.applyDiscount(null);
+    cart.printShoppingCart();
 
     expect(logger.print()).toContain(expectedOutput);
   });
@@ -65,6 +66,7 @@ describe('As a customer', () => {
     ].join('\n');
 
     cart.applyDiscount(Discount.fromCode('PROMO_10'));
+    cart.printShoppingCart();
 
     expect(logger.print()).toContain(expectedOutput);
   });

From b4d9d0d6f7da72fc04ba29ce8dec0a948442b317 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 17:37:02 +0100
Subject: [PATCH 25/29] Iteration6: Creat failing test for scenario

---
 .../shoppingcart.should.test.ts                 | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
index 5e91b35..7c5e947 100644
--- a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
@@ -70,4 +70,21 @@ describe('As a customer', () => {
 
     expect(logger.print()).toContain(expectedOutput);
   });
+
+  test('I want a product count with final price', () => {
+    const logger = new InMemoryLogger();
+    const cart = new InMemoryShoppingCart(logger);
+    addItemsToCart(cart);
+    const expectedOutput = [
+      '|------------------------------------------|',
+      '| Total products: 8                        |',
+      '| Total price: 11.71 €                     |',
+      '--------------------------------------------',
+    ].join('\n');
+    cart.applyDiscount(Discount.fromCode('PROMO_5'));
+
+    cart.printShoppingCart();
+
+    expect(logger.print()).toContain(expectedOutput);
+  });
 });

From 42275c24a24f2d79d60d4a0f5a4e3081fae1e486 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 18:27:48 +0100
Subject: [PATCH 26/29] Iteration6: Make test pass

---
 test-pnpm/shopping-cart-kata/printer.ts             | 13 +++++++++++++
 test-pnpm/shopping-cart-kata/shoppingCart.ts        |  7 +++++++
 .../shopping-cart-kata/shoppingcart.should.test.ts  |  4 ++--
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/printer.ts b/test-pnpm/shopping-cart-kata/printer.ts
index b13722d..2b3bf15 100644
--- a/test-pnpm/shopping-cart-kata/printer.ts
+++ b/test-pnpm/shopping-cart-kata/printer.ts
@@ -2,6 +2,8 @@ import { CartItem } from './cartItem';
 import { Discount } from './discount';
 
 export interface TablePrinter {
+  printTotalPrice(items: CartItem[]): string;
+  printProductCount(items: CartItem[]): string;
   printHeader(): string;
   printCartItem(item: CartItem): string;
   printPromotion(discount: Discount | null): string;
@@ -42,4 +44,15 @@ export class InMemoryTablePrinter implements TablePrinter {
         : 'Promotion:';
     return [this.printHeaderFooter(), `| ${promotionDescription.padEnd(40)} |`].join('\n');
   }
+
+  printProductCount(items: CartItem[]): string {
+    const totalItems = items.reduce((total, item) => total + item.quantity, 0);
+    return `| Total products: ${totalItems.toString().padEnd(24)} |`;
+  }
+
+  printTotalPrice(items: CartItem[]): string {
+    const totalPrice = items.reduce((total, item) => total + item.LineTotal, 0);
+    const description = `Total price: ${totalPrice.toFixed(2)} €`;
+    return `| ${description.padEnd(40)} |`;
+  }
 }
diff --git a/test-pnpm/shopping-cart-kata/shoppingCart.ts b/test-pnpm/shopping-cart-kata/shoppingCart.ts
index c75a7ac..5ef37fe 100644
--- a/test-pnpm/shopping-cart-kata/shoppingCart.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingCart.ts
@@ -30,6 +30,13 @@ export class InMemoryShoppingCart implements ShoppingCart {
     this.logger.clear();
     this.printCartItems();
     this.printDiscounts();
+    this.printTotals();
+  }
+
+  private printTotals() {
+    this.logger.log(this.printer.printProductCount(this.items));
+    this.logger.log(this.printer.printTotalPrice(this.items));
+    this.logger.log(this.printer.printLineSeparator());
   }
 
   private printCartItems(): void {
diff --git a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
index 7c5e947..bce67ed 100644
--- a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
@@ -76,9 +76,9 @@ describe('As a customer', () => {
     const cart = new InMemoryShoppingCart(logger);
     addItemsToCart(cart);
     const expectedOutput = [
-      '|------------------------------------------|',
+      '--------------------------------------------',
       '| Total products: 8                        |',
-      '| Total price: 11.71 €                     |',
+      '| Total price: 12.35 €                     |',
       '--------------------------------------------',
     ].join('\n');
     cart.applyDiscount(Discount.fromCode('PROMO_5'));

From ed72983bd219afc81d0c941317ffdf346cd15442 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 19:11:20 +0100
Subject: [PATCH 27/29] Iteration6: Refactored final passing tests with full
 story and skipped lead up

---
 test-pnpm/shopping-cart-kata/printer.ts       |  7 ++-
 test-pnpm/shopping-cart-kata/shoppingCart.ts  |  2 +-
 .../shoppingcart.should.test.ts               | 55 +++++++++++++++++--
 3 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/printer.ts b/test-pnpm/shopping-cart-kata/printer.ts
index 2b3bf15..582336f 100644
--- a/test-pnpm/shopping-cart-kata/printer.ts
+++ b/test-pnpm/shopping-cart-kata/printer.ts
@@ -2,7 +2,7 @@ import { CartItem } from './cartItem';
 import { Discount } from './discount';
 
 export interface TablePrinter {
-  printTotalPrice(items: CartItem[]): string;
+  printTotalPrice(items: CartItem[], discount: Discount | null): string;
   printProductCount(items: CartItem[]): string;
   printHeader(): string;
   printCartItem(item: CartItem): string;
@@ -50,9 +50,10 @@ export class InMemoryTablePrinter implements TablePrinter {
     return `| Total products: ${totalItems.toString().padEnd(24)} |`;
   }
 
-  printTotalPrice(items: CartItem[]): string {
+  printTotalPrice(items: CartItem[], discount: Discount | null): string {
     const totalPrice = items.reduce((total, item) => total + item.LineTotal, 0);
-    const description = `Total price: ${totalPrice.toFixed(2)} €`;
+    const discountedAmount = discount ? discount.applyTo(totalPrice) : totalPrice;
+    const description = `Total price: ${discountedAmount.toFixed(2)} €`;
     return `| ${description.padEnd(40)} |`;
   }
 }
diff --git a/test-pnpm/shopping-cart-kata/shoppingCart.ts b/test-pnpm/shopping-cart-kata/shoppingCart.ts
index 5ef37fe..460f4d0 100644
--- a/test-pnpm/shopping-cart-kata/shoppingCart.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingCart.ts
@@ -35,7 +35,7 @@ export class InMemoryShoppingCart implements ShoppingCart {
 
   private printTotals() {
     this.logger.log(this.printer.printProductCount(this.items));
-    this.logger.log(this.printer.printTotalPrice(this.items));
+    this.logger.log(this.printer.printTotalPrice(this.items, this.discounts[0] ?? null));
     this.logger.log(this.printer.printLineSeparator());
   }
 
diff --git a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
index bce67ed..256df45 100644
--- a/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingcart.should.test.ts
@@ -20,7 +20,7 @@ describe('As a customer', () => {
     cart.addItem(new CartItem(corn, 1));
   }
 
-  test('I want to add items to my shopping cart', () => {
+  test.skip('I want to add items to my shopping cart', () => {
     const logger = new InMemoryLogger();
     const cart = new InMemoryShoppingCart(logger);
     const expectedOutput = [
@@ -40,7 +40,7 @@ describe('As a customer', () => {
     expect(logger.print()).toContain(expectedOutput);
   });
 
-  test('I want to create a promotion section for no promotions', () => {
+  test.skip('I want to create a promotion section for no promotions', () => {
     const logger = new InMemoryLogger();
     const cart = new InMemoryShoppingCart(logger);
     addItemsToCart(cart);
@@ -55,7 +55,7 @@ describe('As a customer', () => {
     expect(logger.print()).toContain(expectedOutput);
   });
 
-  test('I want to create a promotion section for an actual promotion', () => {
+  test.skip('I want to create a promotion section for an actual promotion', () => {
     const logger = new InMemoryLogger();
     const cart = new InMemoryShoppingCart(logger);
     addItemsToCart(cart);
@@ -78,7 +78,7 @@ describe('As a customer', () => {
     const expectedOutput = [
       '--------------------------------------------',
       '| Total products: 8                        |',
-      '| Total price: 12.35 €                     |',
+      '| Total price: 11.74 €                     |',
       '--------------------------------------------',
     ].join('\n');
     cart.applyDiscount(Discount.fromCode('PROMO_5'));
@@ -87,4 +87,51 @@ describe('As a customer', () => {
 
     expect(logger.print()).toContain(expectedOutput);
   });
+
+  test('I want to print an empty cart', () => {
+    const logger = new InMemoryLogger();
+    const cart = new InMemoryShoppingCart(logger);
+    const expectedOutput = [
+      '--------------------------------------------',
+      '| Product name | Price with VAT | Quantity |',
+      '| ------------ | -------------- | -------- |',
+      '|------------------------------------------|',
+      '| Promotion:                               |',
+      '--------------------------------------------',
+      '| Total products: 0                        |',
+      '| Total price: 0.00 €                      |',
+      '--------------------------------------------',
+    ].join('\n');
+
+    cart.printShoppingCart();
+
+    expect(logger.print()).toBe(expectedOutput);
+  });
+
+  test('I want to print a full discounted list', () => {
+    const logger = new InMemoryLogger();
+    const cart = new InMemoryShoppingCart(logger);
+    addItemsToCart(cart);
+    cart.applyDiscount(Discount.fromCode('PROMO_10'));
+    const expectedOutput = [
+      '--------------------------------------------',
+      '| Product name | Price with VAT | Quantity |',
+      '| ------------ | -------------- | -------- |',
+      '| Iceberg 🥬   | 2.17 €         | 3        |',
+      '| Tomato 🍅    | 0.73 €         | 1        |',
+      '| Chicken 🍗   | 1.83 €         | 1        |',
+      '| Bread 🍞     | 0.89 €         | 2        |',
+      '| Corn 🌽      | 1.50 €         | 1        |',
+      '|------------------------------------------|',
+      '| Promotion: 10% off with code PROMO_10    |',
+      '--------------------------------------------',
+      '| Total products: 8                        |',
+      '| Total price: 11.12 €                     |',
+      '--------------------------------------------',
+    ].join('\n');
+
+    cart.printShoppingCart();
+
+    expect(logger.print()).toBe(expectedOutput);
+  });
 });

From 8f87fbc27e977a77328db46ec0aad11b0fa6d5a3 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Tue, 6 May 2025 20:19:31 +0100
Subject: [PATCH 28/29] Iteration6: Refactor magic strings and printer patterns
 Fix small typo in test

---
 test-pnpm/shopping-cart-kata/README.md        |  4 ++
 test-pnpm/shopping-cart-kata/constants.ts     | 15 +++++
 .../discount.should.test.ts                   |  2 +-
 test-pnpm/shopping-cart-kata/printer.ts       | 67 +++++++++++++------
 test-pnpm/shopping-cart-kata/shoppingCart.ts  |  4 +-
 5 files changed, 68 insertions(+), 24 deletions(-)
 create mode 100644 test-pnpm/shopping-cart-kata/constants.ts

diff --git a/test-pnpm/shopping-cart-kata/README.md b/test-pnpm/shopping-cart-kata/README.md
index b95ebc0..b28c9a0 100644
--- a/test-pnpm/shopping-cart-kata/README.md
+++ b/test-pnpm/shopping-cart-kata/README.md
@@ -199,3 +199,7 @@ You could start Outside-In **only** if:
 - You're willing to mock deeper domain types (`Product`, `CartItem`, etc.)
 
 But in this kata, that’s harder to justify because the logic in the "leaf" types is richer and more test-worthy than in the orchestration layer.
+
+### Summary
+
+Thnanks Emmanuael Valverde, for your cool takle on this [kata](https://www.codurance.com/katas/shopping-cart-kata). There were a few sneaky catches with the pricing. I have done this kata before using simple types and I found myself producing more code this time. I also did outside in, before, mocking and faking bits until I had the final design. I think breaking this up into  the seperate phases made it easier to get my head around each concept, so I am glad I did it this way. The thing didn't like is it forced me into a solution by virtue of what I simplified. It may be a good or bad thing, no idea. 
diff --git a/test-pnpm/shopping-cart-kata/constants.ts b/test-pnpm/shopping-cart-kata/constants.ts
new file mode 100644
index 0000000..2877e3f
--- /dev/null
+++ b/test-pnpm/shopping-cart-kata/constants.ts
@@ -0,0 +1,15 @@
+
+export const TABLE_CONSTANTS = {
+  LINE_WIDTH: 44,
+  COLUMN_WIDTHS: {
+    NAME: 12,
+    PRICE: 14,
+    QUANTITY: 8,
+  },
+  PADDING_WIDTH: 40,
+  CURRENCY: '€',
+  SEPARATORS: {
+    HORIZONTAL: '-',
+    VERTICAL: '|',
+  },
+};
diff --git a/test-pnpm/shopping-cart-kata/discount.should.test.ts b/test-pnpm/shopping-cart-kata/discount.should.test.ts
index 54aea3b..1e4e299 100644
--- a/test-pnpm/shopping-cart-kata/discount.should.test.ts
+++ b/test-pnpm/shopping-cart-kata/discount.should.test.ts
@@ -14,7 +14,7 @@ describe('Discount should', () => {
     expect(discount).toBeNull();
   });
 
-  it('alculate a discount from a price', () => {
+  it('calculate a discount from a price', () => {
     const discount = Discount.fromCode('PROMO_10')!;
     expect(discount.applyTo(100)).toBe(90);
   });
diff --git a/test-pnpm/shopping-cart-kata/printer.ts b/test-pnpm/shopping-cart-kata/printer.ts
index 582336f..93d7f54 100644
--- a/test-pnpm/shopping-cart-kata/printer.ts
+++ b/test-pnpm/shopping-cart-kata/printer.ts
@@ -1,4 +1,5 @@
 import { CartItem } from './cartItem';
+import { TABLE_CONSTANTS } from './constants';
 import { Discount } from './discount';
 
 export interface TablePrinter {
@@ -11,49 +12,73 @@ export interface TablePrinter {
   printHeaderFooter(): string;
 }
 
-export class InMemoryTablePrinter implements TablePrinter {
+export class DefaultTablePrinter implements TablePrinter {
   printHeader(): string {
     return [
-      '--------------------------------------------',
-      '| Product name | Price with VAT | Quantity |',
-      '| ------------ | -------------- | -------- |',
+      this.printLineSeparator(),
+      `${TABLE_CONSTANTS.SEPARATORS.VERTICAL} Product name ${TABLE_CONSTANTS.SEPARATORS.VERTICAL} Price with VAT ${TABLE_CONSTANTS.SEPARATORS.VERTICAL} Quantity ${TABLE_CONSTANTS.SEPARATORS.VERTICAL}`,
+      `${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${'-'.repeat(TABLE_CONSTANTS.COLUMN_WIDTHS.NAME)} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${'-'.repeat(TABLE_CONSTANTS.COLUMN_WIDTHS.PRICE)} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${'-'.repeat(TABLE_CONSTANTS.COLUMN_WIDTHS.QUANTITY)} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL}`,
     ].join('\n');
   }
 
   printHeaderFooter(): string {
-    return '|------------------------------------------|';
+    return `${TABLE_CONSTANTS.SEPARATORS.VERTICAL}${'-'.repeat(TABLE_CONSTANTS.LINE_WIDTH - 2)}${TABLE_CONSTANTS.SEPARATORS.VERTICAL}`;
   }
 
   printCartItem(item: CartItem): string {
-    const name = item.product.name.padEnd(12);
-    const priceWithVat = `${item.product.finalPrice.toFixed(2)} €`.padEnd(14);
-    const quantity = item.quantity.toString().padEnd(8);
+    const name = item.product.name.padEnd(TABLE_CONSTANTS.COLUMN_WIDTHS.NAME);
+    const priceWithVat =
+      `${this.formatPrice(item.product.finalPrice)} ${TABLE_CONSTANTS.CURRENCY}`.padEnd(
+        TABLE_CONSTANTS.COLUMN_WIDTHS.PRICE,
+      );
+    const quantity = item.quantity.toString().padEnd(TABLE_CONSTANTS.COLUMN_WIDTHS.QUANTITY);
 
-    return `| ${name} | ${priceWithVat} | ${quantity} |`;
+    return `${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${name} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${priceWithVat} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${quantity} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL}`;
   }
 
   printLineSeparator(): string {
-    return '--------------------------------------------';
+    return TABLE_CONSTANTS.SEPARATORS.HORIZONTAL.repeat(TABLE_CONSTANTS.LINE_WIDTH);
   }
 
   printPromotion(discount: Discount | null): string {
-    const promotionCode = discount?.code ?? '';
-    const promotionDescription =
-      discount != null
-        ? `Promotion: ${discount?.percentage * 100}% off with code ${promotionCode}`
-        : 'Promotion:';
-    return [this.printHeaderFooter(), `| ${promotionDescription.padEnd(40)} |`].join('\n');
+    const promotionDescription = this.formatPromotionDescription(discount);
+    return [
+      this.printHeaderFooter(),
+      `${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${promotionDescription.padEnd(TABLE_CONSTANTS.PADDING_WIDTH)} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL}`,
+    ].join('\n');
   }
 
   printProductCount(items: CartItem[]): string {
-    const totalItems = items.reduce((total, item) => total + item.quantity, 0);
-    return `| Total products: ${totalItems.toString().padEnd(24)} |`;
+    const totalItems = this.calculateTotalItems(items);
+    return `${TABLE_CONSTANTS.SEPARATORS.VERTICAL} Total products: ${totalItems.toString().padEnd(24)} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL}`;
   }
 
   printTotalPrice(items: CartItem[], discount: Discount | null): string {
-    const totalPrice = items.reduce((total, item) => total + item.LineTotal, 0);
+    const totalPrice = this.calculateTotalPrice(items);
     const discountedAmount = discount ? discount.applyTo(totalPrice) : totalPrice;
-    const description = `Total price: ${discountedAmount.toFixed(2)} €`;
-    return `| ${description.padEnd(40)} |`;
+    const description = `Total price: ${this.formatPrice(discountedAmount)} ${TABLE_CONSTANTS.CURRENCY}`;
+
+    return `${TABLE_CONSTANTS.SEPARATORS.VERTICAL} ${description.padEnd(TABLE_CONSTANTS.PADDING_WIDTH)} ${TABLE_CONSTANTS.SEPARATORS.VERTICAL}`;
+  }
+
+  private formatPromotionDescription(discount: Discount | null): string {
+    if (discount == null) {
+      return 'Promotion:';
+    }
+
+    const percentage = Math.round(discount.percentage * 100);
+    return `Promotion: ${percentage}% off with code ${discount.code}`;
+  }
+
+  private calculateTotalItems(items: CartItem[]): number {
+    return items.reduce((total, item) => total + item.quantity, 0);
+  }
+
+  private calculateTotalPrice(items: CartItem[]): number {
+    return items.reduce((total, item) => total + item.LineTotal, 0);
+  }
+
+  private formatPrice(price: number): string {
+    return price.toFixed(2);
   }
 }
diff --git a/test-pnpm/shopping-cart-kata/shoppingCart.ts b/test-pnpm/shopping-cart-kata/shoppingCart.ts
index 460f4d0..e315f20 100644
--- a/test-pnpm/shopping-cart-kata/shoppingCart.ts
+++ b/test-pnpm/shopping-cart-kata/shoppingCart.ts
@@ -1,7 +1,7 @@
 import { CartItem } from './cartItem';
 import { Discount } from './discount';
 import { Logger } from './logger';
-import { InMemoryTablePrinter, TablePrinter } from './printer';
+import { DefaultTablePrinter, TablePrinter } from './printer';
 
 export interface ShoppingCart {
   addItem(cartItem: CartItem): void;
@@ -12,7 +12,7 @@ export interface ShoppingCart {
 export class InMemoryShoppingCart implements ShoppingCart {
   private items: CartItem[] = [];
   private discounts: Discount[] = [];
-  private printer: TablePrinter = new InMemoryTablePrinter();
+  private printer: TablePrinter = new DefaultTablePrinter();
 
   constructor(private logger: Logger) {}
 

From 3132415a64eab87068c2da8b42796783b6243ce5 Mon Sep 17 00:00:00 2001
From: Vincent Farah <vincent.farah@gbgplc.com>
Date: Mon, 12 May 2025 08:50:10 +0100
Subject: [PATCH 29/29] Add some future tasks to extend this and fix some typos

---
 test-pnpm/shopping-cart-kata/README.md | 44 +++++++++++++++-----------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/test-pnpm/shopping-cart-kata/README.md b/test-pnpm/shopping-cart-kata/README.md
index b28c9a0..f9c7aa7 100644
--- a/test-pnpm/shopping-cart-kata/README.md
+++ b/test-pnpm/shopping-cart-kata/README.md
@@ -11,13 +11,13 @@ We are building a shopping cart for an online grocery shop. The idea of this kat
 
 ### List of products
 
-| **Name**      | **Cost** | **% Revenue** | **Price per unit** | **Tax**                 | **Final price** |
-| ------------- | -------- | ------------- | ------------------ | ----------------------- | --------------- |
-| **Iceberg 🥬** | *1.55 €* | *15 %*        | 1,79 €             | *Normal (21%)*          | 2.17 €          |
-| **Tomato 🍅**  | *0.52 €* | *15 %*        | 0.60 €             | *Normal (21%)*          | 0.73 €          |
-| **Chicken 🍗** | *1.34 €* | *12 %*        | 1.51 €             | *Normal (21%)*          | 1.83 €          |
-| **Bread 🍞**   | *0.71 €* | *12 %*        | 0.80 €             | *First necessity (10%)* | 0.89 €          |
-| **Corn 🌽**    | *1.21 €* | *12 %*        | 1.36 €             | *First necessity (10%)* | 1.50 €          |
+| **Name**       | **Cost** | **% Revenue** | **Price per unit** | **Tax**                 | **Final price** |
+| -------------- | -------- | ------------- | ------------------ | ----------------------- | --------------- |
+| **Iceberg 🥬** | _1.55 €_ | _15 %_        | 1,79 €             | _Normal (21%)_          | 2.17 €          |
+| **Tomato 🍅**  | _0.52 €_ | _15 %_        | 0.60 €             | _Normal (21%)_          | 0.73 €          |
+| **Chicken 🍗** | _1.34 €_ | _12 %_        | 1.51 €             | _Normal (21%)_          | 1.83 €          |
+| **Bread 🍞**   | _0.71 €_ | _12 %_        | 0.80 €             | _First necessity (10%)_ | 0.89 €          |
+| **Corn 🌽**    | _1.21 €_ | _12 %_        | 1.36 €             | _First necessity (10%)_ | 1.50 €          |
 
 ### List of discounts
 
@@ -150,9 +150,12 @@ We are building a shopping cart for an online grocery shop. The idea of this kat
 ```javascript
 export interface ShoppingCart {
   addItem(cartItem: CartItem): void;
-  deleteItem(cartItem: CartItem): void;
   applyDiscount(discount: Discount): void;
   printShoppingCart(): void;
+  // TODO
+  removeItem(name: string): void;
+  updateItemQuantity(name: string, quantity: number): void;
+  getItems(): ReadonlyArray<CartItem>;
 }
 ```
 
@@ -162,15 +165,18 @@ export interface ShoppingCart {
 
 ##### Suggested Inside-Out Iterations (with TDD focus)
 
-| Iteration | Focus                                    | Why Start Here?                              |
-| --------- | ---------------------------------------- | -------------------------------------------- |
-| 1         | `Product` - price per unit and VAT logic | Small, atomic, pure — perfect TDD start      |
-| 2         | `CartItem` - quantity & total price      | Introduces aggregation, still isolated logic |
-| 3         | `Discount` - percentage logic            | Stateless, predictable, complements pricing  |
-| 4         | `ShoppingCart` - add/remove items        | Start using composition of domain elements   |
-| 5         | `ShoppingCart` - apply discount          | Introduces first mutation to cart state      |
-| 6         | `ShoppingCart` - total price & print     | Drives end-to-end expectation-based testing  |
-| 7         | `ProductCatalogue` or Registry           | Encapsulate product lookup and validation    |
+| Iteration | Focus                                    | Why Start Here?                                              |
+| --------- | ---------------------------------------- | ------------------------------------------------------------ |
+| 1         | `Product` - price per unit and VAT logic | Small, atomic, pure — perfect TDD start                      |
+| 2         | `CartItem` - quantity & total price      | Introduces aggregation, still isolated logic                 |
+| 3         | `Discount` - percentage logic            | Stateless, predictable, complements pricing                  |
+| 4         | `ShoppingCart` - add items               | Start using composition of domain elements                   |
+| 5         | `ShoppingCart` - apply discount          | Introduces first mutation to cart state                      |
+| 6         | `ShoppingCart` - total price & print     | Drives end-to-end expectation-based testing                  |
+| 7         | `ProductCatalogue` or Registry           | Encapsulate product lookup and validation                    |
+| 8         | `ShoppingCart` - delete items            | TODO - Drive removing Items from the cart                    |
+| 9         | `ShoppingCart` - updateItemQuantity      | TODO - Drive changing the quantity                           |
+| 10        | `ShoppingCart` - getItems                | TODO - Drive getting the items to be more inline with a cart |
 
 ### Evolution Flow Summary
 
@@ -191,7 +197,7 @@ export interface ShoppingCart {
 - `print()` or `toString()` as test-driving format rendering
 - Possibly inject or access product catalogue here
 
-### When to Consider *Outside-In*
+### When to Consider _Outside-In_
 
 You could start Outside-In **only** if:
 
@@ -202,4 +208,4 @@ But in this kata, that’s harder to justify because the logic in the "leaf" typ
 
 ### Summary
 
-Thnanks Emmanuael Valverde, for your cool takle on this [kata](https://www.codurance.com/katas/shopping-cart-kata). There were a few sneaky catches with the pricing. I have done this kata before using simple types and I found myself producing more code this time. I also did outside in, before, mocking and faking bits until I had the final design. I think breaking this up into  the seperate phases made it easier to get my head around each concept, so I am glad I did it this way. The thing didn't like is it forced me into a solution by virtue of what I simplified. It may be a good or bad thing, no idea. 
+Thanks Emmanuael Valverde, for your cool take on this [kata](https://www.codurance.com/katas/shopping-cart-kata). There were a few sneaky catches with the pricing. I have done this kata before using simple types and I found myself producing more code this time. I also did outside in, before, mocking and faking bits until I had the final design. I think breaking this up into the seperate phases made it easier to get my head around each concept, so I am glad I did it this way. The thing didn't like is it forced me into a solution by virtue of what I simplified. It may be a good or bad thing, no idea.