Implement support for throw expressions in expression trees#19
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Implement support for throw expressions in expression trees#19
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tests/ExpressiveSharp.IntegrationTests.ExpressionCompile/Tests/Common/ThrowExpressionTests.cs
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Pull request overview
This PR adds end-to-end support for C# throw expressions in ExpressiveSharp-generated expression trees, including emission, EF Core compatibility behavior, and test/docs updates.
Changes:
- Added generator emission for
IThrowOperation(including typedExpression.Throw(exception, typeof(T))) and updated block-body handling to allow throws. - Added an EF Core-facing transformer (
ReplaceThrowWithDefault) and an EF configuration switch to preserve throws instead of replacing them. - Added/updated unit, generator snapshot, and integration tests plus documentation to cover throw-expression scenarios.
Reviewed changes
Copilot reviewed 18 out of 18 changed files in this pull request and generated 6 comments.
Show a summary per file
| File | Description |
|---|---|
| tests/ExpressiveSharp.Tests/Transformers/ReplaceThrowWithDefaultTests.cs | Adds unit tests validating throw→default rewriting behavior. |
| tests/ExpressiveSharp.IntegrationTests/Scenarios/Store/Models/Order.cs | Adds [Expressive] property using ?? throw as a real scenario. |
| tests/ExpressiveSharp.IntegrationTests/Scenarios/Common/Tests/ThrowExpressionTests.cs | Adds scenario tests for SafeTag expansion behavior. |
| tests/ExpressiveSharp.IntegrationTests.ExpressionCompile/Tests/Common/ThrowExpressionTests.cs | Wires the scenario tests into the ExpressionCompile runner. |
| tests/ExpressiveSharp.Generator.Tests/ExpressiveGenerator/ThrowExpressionTests.cs | Adds generator tests for throw in coalesce/conditional/switch arm. |
| tests/ExpressiveSharp.Generator.Tests/ExpressiveGenerator/*.verified.txt | Snapshot outputs for new throw-expression generator cases. |
| tests/ExpressiveSharp.Generator.Tests/ExpressiveGenerator/DiagnosticTests.cs | Removes prior “throw is unsupported” diagnostic test. |
| tests/ExpressiveSharp.Generator.Tests/ExpressiveGenerator/BlockBodyTests.cs + verified | Updates expectations: throw in block bodies is now emitted, not warned. |
| src/ExpressiveSharp/Transformers/ReplaceThrowWithDefault.cs | Introduces the transformer used to remove throw nodes for provider compatibility. |
| src/ExpressiveSharp.Generator/Interpretation/ExpressiveInterpreter.BodyProcessors.cs | Stops flagging IThrowOperation as unsupported in block bodies. |
| src/ExpressiveSharp.Generator/Emitter/ExpressionTreeEmitter.cs | Implements throw emission and conversion special-casing for throw operands. |
| src/ExpressiveSharp.EntityFrameworkCore/.../ExpressiveOptionsExtension.cs | Adds default throw-stripping behavior for EF Core, plus opt-out. |
| src/ExpressiveSharp.EntityFrameworkCore/Extensions/DbContextOptionsExtensions.cs | Passes the new preserve-throws option into the EF extension. |
| src/ExpressiveSharp.EntityFrameworkCore/ExpressiveOptionsBuilder.cs | Adds PreserveThrowExpressions() option for EF integration configuration. |
| docs/advanced/ioperation-mapping.md | Documents IThrowOperation mapping and EF compatibility behavior. |
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tests/ExpressiveSharp.IntegrationTests/Scenarios/Common/Tests/ThrowExpressionTests.cs
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| Expression<Func<Order, string>> expr = o => o.SafeTag; | ||
| var expanded = (Expression<Func<Order, string>>)expr.ExpandExpressives(); | ||
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| // Compile and invoke directly — non-null Tag should return the value | ||
| var compiled = expanded.Compile(); | ||
| var order = new Order { Tag = "RUSH" }; | ||
| Assert.AreEqual("RUSH", compiled(order)); | ||
| } |
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These integration tests compile/invoke the expanded expression directly instead of executing it via Runner (like other scenario tests do). As a result, they don’t actually validate behavior across integration runners / LINQ providers and won’t catch translation-time issues.
tests/ExpressiveSharp.Generator.Tests/ExpressiveGenerator/ThrowExpressionTests.cs
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...Sharp.Generator.Tests/ExpressiveGenerator/ThrowExpressionTests.ThrowInSwitchArm.verified.txt
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src/ExpressiveSharp.EntityFrameworkCore/ExpressiveOptionsBuilder.cs
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| [TestClass] | ||
| public class ThrowExpressionTests : Scenarios.Common.Tests.ThrowExpressionTests | ||
| { | ||
| protected override IIntegrationTestRunner CreateRunner() => new ExpressionCompileTestRunner(); |
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This adds the scenario test to the ExpressionCompile runner, but there’s no corresponding derived test in ExpressiveSharp.IntegrationTests.EntityFrameworkCore (search shows no ThrowExpressionTests there). To validate provider compatibility as described in the PR, add the EF Core runner variant as well.
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Add support for throw expressions in expression trees, enabling their use in null-coalescing and other scenarios. Include tests to verify correct behavior and ensure compatibility with LINQ providers. Update related components to handle throw expressions appropriately.