diff --git a/examples/counterAndGauge.js b/examples/counterAndGauge.js
index b3a476a..07903bb 100644
--- a/examples/counterAndGauge.js
+++ b/examples/counterAndGauge.js
@@ -9,7 +9,7 @@ var counter = client.newCounter({
     help: "The number of counter intervals that have elapsed."
 });
 
-gauge = client.newGauge({
+var gauge = client.newGauge({
     namespace: "counter_test",
     name: "random_number",
     help: "A random number we occasionally set."
diff --git a/js/base_metric.js b/js/base_metric.js
index e16a433..791e710 100644
--- a/js/base_metric.js
+++ b/js/base_metric.js
@@ -1,9 +1,7 @@
-var BaseMetric, debug, hash, _;
+var BaseMetric, debug, hash;
 
 debug = require("debug")("prometheus-client:metric");
 
-_ = require("underscore");
-
 hash = require("object-hash");
 
 module.exports = BaseMetric = (function() {
@@ -22,7 +20,9 @@ module.exports = BaseMetric = (function() {
     if (!this.help) {
       throw "Help is required";
     }
-    this._full_name = _.compact([this.namespace, this.subsystem, this.name]).join("_");
+    this._full_name = [this.namespace, this.subsystem, this.name].filter(function(s) {
+      return s;
+    }).join("_");
   }
 
   BaseMetric.prototype.type = function() {
@@ -64,7 +64,7 @@ module.exports = BaseMetric = (function() {
       if (/^__/.test(k)) {
         throw "Label " + k + " must not start with __";
       }
-      if (_(['instance', 'job']).contains(k)) {
+      if ('instance' === k || 'job' === k) {
         throw "Label " + k + " is reserved";
       }
     }
diff --git a/js/base_metric.js.map b/js/base_metric.js.map
index 89fc77b..ca81bc2 100644
--- a/js/base_metric.js.map
+++ b/js/base_metric.js.map
@@ -6,5 +6,5 @@
     "base_metric.coffee"
   ],
   "names": [],
-  "mappings": "AAAA,IAAA,0BAAA;;AAAA,KAAA,GAAU,OAAA,CAAQ,OAAR,CAAA,CAAiB,0BAAjB,CAAV,CAAA;;AAAA,CACA,GAAU,OAAA,CAAQ,YAAR,CADV,CAAA;;AAAA,IAEA,GAAU,OAAA,CAAQ,aAAR,CAFV,CAAA;;AAAA,MAIM,CAAC,OAAP,GAAuB;AAEN,EAAA,oBAAC,IAAD,GAAA;AACT,IAAA,IAAC,CAAA,IAAD,kBAAkB,IAAI,CAAE,aAAxB,CAAA;AAAA,IACA,IAAC,CAAA,SAAD,kBAAkB,IAAI,CAAE,kBADxB,CAAA;AAAA,IAEA,IAAC,CAAA,SAAD,kBAAkB,IAAI,CAAE,kBAFxB,CAAA;AAAA,IAGA,IAAC,CAAA,IAAD,kBAAkB,IAAI,CAAE,aAHxB,CAAA;AAAA,IAIA,IAAC,CAAA,WAAD,kBAAkB,IAAI,CAAE,eAJxB,CAAA;AAAA,IAOA,IAAC,CAAA,OAAD,GAAkB,EAPlB,CAAA;AAAA,IAUA,IAAC,CAAA,WAAD,GAAkB,EAVlB,CAAA;AAAA,IAWA,IAAC,CAAA,UAAD,GAAkB,IAXlB,CAAA;AAaA,IAAA,IAA4B,CAAA,IAAE,CAAA,IAA9B;AAAA,YAAM,kBAAN,CAAA;KAbA;AAcA,IAAA,IAA4B,CAAA,IAAE,CAAA,IAA9B;AAAA,YAAM,kBAAN,CAAA;KAdA;AAAA,IAgBA,IAAC,CAAA,UAAD,GAAkB,CAAC,CAAC,OAAF,CAAU,CAAE,IAAC,CAAA,SAAH,EAAc,IAAC,CAAA,SAAf,EAA0B,IAAC,CAAA,IAA3B,CAAV,CAA4C,CAAC,IAA7C,CAAkD,GAAlD,CAhBlB,CADS;EAAA,CAAb;;AAAA,uBAqBA,IAAA,GAAM,SAAA,GAAA;AACF,UAAM,yBAAN,CADE;EAAA,CArBN,CAAA;;AAAA,uBA0BA,UAAA,GAAS,SAAA,GAAA;WACL,KADK;EAAA,CA1BT,CAAA;;AAAA,uBA+BA,GAAA,GAAK,SAAC,MAAD,GAAA;AACD,QAAA,EAAA;;MADE,SAAO;KACT;AAAA,IAAA,EAAA,GAAK,IAAC,CAAA,cAAD,CAAgB,MAAhB,CAAL,CAAA;WACA,IAAC,CAAA,OAAQ,CAAA,EAAA,CAAT,IAAgB,IAAC,CAAA,SAAA,CAAD,CAAA,EAFf;EAAA,CA/BL,CAAA;;AAAA,uBAqCA,MAAA,GAAQ,SAAA,GAAA;AACJ,QAAA,mBAAA;AAAA,IAAA,MAAA,GAAS,EAAT,CAAA;AAEA;AAAA,SAAA,UAAA;mBAAA;AACI,MAAA,MAAM,CAAC,IAAP,CAAY,CAAC,IAAC,CAAA,WAAY,CAAA,EAAA,CAAd,EAAmB,CAAnB,CAAZ,CAAA,CADJ;AAAA,KAFA;WAKA,OANI;EAAA,CArCR,CAAA;;AAAA,uBA+CA,cAAA,GAAgB,SAAC,MAAD,GAAA;AACZ,QAAA,QAAA;AAAA,IAAA,EAAA,GAAK,IAAI,CAAC,IAAL,CAAU,MAAV,CAAL,CAAA;AAEA,IAAA,IAAa,IAAC,CAAA,WAAY,CAAA,EAAA,CAA1B;AAAA,aAAO,EAAP,CAAA;KAFA;AAKA,SAAA,WAAA;oBAAA;AACI,MAAA,IAA6C,KAAK,CAAC,IAAN,CAAW,CAAX,CAA7C;AAAA,cAAO,QAAA,GAAQ,CAAR,GAAU,yBAAjB,CAAA;OAAA;AACA,MAAA,IAAkC,CAAA,CAAE,CAAC,UAAD,EAAY,KAAZ,CAAF,CAAqB,CAAC,QAAtB,CAA+B,CAA/B,CAAlC;AAAA,cAAO,QAAA,GAAQ,CAAR,GAAU,cAAjB,CAAA;OAFJ;AAAA,KALA;AAUA,IAAA,IAAG,IAAC,CAAA,UAAD,IAAe,IAAI,CAAC,IAAL,CAAU,MAAV,CAAA,KAAqB,IAAC,CAAA,UAAxC;AACI,YAAM,qCAAN,CADJ;KAVA;AAcA,IAAA,IAAmC,CAAA,IAAE,CAAA,UAArC;AAAA,MAAA,IAAC,CAAA,UAAD,GAAc,IAAI,CAAC,IAAL,CAAU,MAAV,CAAd,CAAA;KAdA;AAAA,IAeA,IAAC,CAAA,WAAY,CAAA,EAAA,CAAb,GAAmB,MAfnB,CAAA;WAiBA,GAlBY;EAAA,CA/ChB,CAAA;;oBAAA;;IANJ,CAAA"
+  "mappings": "AAAA,IAAA,uBAAA;;AAAA,KAAA,GAAU,OAAA,CAAQ,OAAR,CAAA,CAAiB,0BAAjB,CAAV,CAAA;;AAAA,IACA,GAAU,OAAA,CAAQ,aAAR,CADV,CAAA;;AAAA,MAGM,CAAC,OAAP,GAAuB;AAEN,EAAA,oBAAC,IAAD,GAAA;AACT,IAAA,IAAC,CAAA,IAAD,kBAAkB,IAAI,CAAE,aAAxB,CAAA;AAAA,IACA,IAAC,CAAA,SAAD,kBAAkB,IAAI,CAAE,kBADxB,CAAA;AAAA,IAEA,IAAC,CAAA,SAAD,kBAAkB,IAAI,CAAE,kBAFxB,CAAA;AAAA,IAGA,IAAC,CAAA,IAAD,kBAAkB,IAAI,CAAE,aAHxB,CAAA;AAAA,IAIA,IAAC,CAAA,WAAD,kBAAkB,IAAI,CAAE,eAJxB,CAAA;AAAA,IAOA,IAAC,CAAA,OAAD,GAAkB,EAPlB,CAAA;AAAA,IAUA,IAAC,CAAA,WAAD,GAAkB,EAVlB,CAAA;AAAA,IAWA,IAAC,CAAA,UAAD,GAAkB,IAXlB,CAAA;AAaA,IAAA,IAA4B,CAAA,IAAE,CAAA,IAA9B;AAAA,YAAM,kBAAN,CAAA;KAbA;AAcA,IAAA,IAA4B,CAAA,IAAE,CAAA,IAA9B;AAAA,YAAM,kBAAN,CAAA;KAdA;AAAA,IAgBA,IAAC,CAAA,UAAD,GAAkB,CAAE,IAAC,CAAA,SAAH,EAAc,IAAC,CAAA,SAAf,EAA0B,IAAC,CAAA,IAA3B,CAAiC,CAAC,MAAlC,CAAyC,SAAC,CAAD,GAAA;aAAK,EAAL;IAAA,CAAzC,CAAgD,CAAC,IAAjD,CAAsD,GAAtD,CAhBlB,CADS;EAAA,CAAb;;AAAA,uBAqBA,IAAA,GAAM,SAAA,GAAA;AACF,UAAM,yBAAN,CADE;EAAA,CArBN,CAAA;;AAAA,uBA0BA,UAAA,GAAS,SAAA,GAAA;WACL,KADK;EAAA,CA1BT,CAAA;;AAAA,uBA+BA,GAAA,GAAK,SAAC,MAAD,GAAA;AACD,QAAA,EAAA;;MADE,SAAO;KACT;AAAA,IAAA,EAAA,GAAK,IAAC,CAAA,cAAD,CAAgB,MAAhB,CAAL,CAAA;WACA,IAAC,CAAA,OAAQ,CAAA,EAAA,CAAT,IAAgB,IAAC,CAAA,SAAA,CAAD,CAAA,EAFf;EAAA,CA/BL,CAAA;;AAAA,uBAqCA,MAAA,GAAQ,SAAA,GAAA;AACJ,QAAA,mBAAA;AAAA,IAAA,MAAA,GAAS,EAAT,CAAA;AAEA;AAAA,SAAA,UAAA;mBAAA;AACI,MAAA,MAAM,CAAC,IAAP,CAAY,CAAC,IAAC,CAAA,WAAY,CAAA,EAAA,CAAd,EAAmB,CAAnB,CAAZ,CAAA,CADJ;AAAA,KAFA;WAKA,OANI;EAAA,CArCR,CAAA;;AAAA,uBA+CA,cAAA,GAAgB,SAAC,MAAD,GAAA;AACZ,QAAA,QAAA;AAAA,IAAA,EAAA,GAAK,IAAI,CAAC,IAAL,CAAU,MAAV,CAAL,CAAA;AAEA,IAAA,IAAa,IAAC,CAAA,WAAY,CAAA,EAAA,CAA1B;AAAA,aAAO,EAAP,CAAA;KAFA;AAKA,SAAA,WAAA;oBAAA;AACI,MAAA,IAA6C,KAAK,CAAC,IAAN,CAAW,CAAX,CAA7C;AAAA,cAAO,QAAA,GAAQ,CAAR,GAAU,yBAAjB,CAAA;OAAA;AACA,MAAA,IAAkC,UAAA,KAAY,CAAZ,IAAiB,KAAA,KAAO,CAA1D;AAAA,cAAO,QAAA,GAAQ,CAAR,GAAU,cAAjB,CAAA;OAFJ;AAAA,KALA;AAUA,IAAA,IAAG,IAAC,CAAA,UAAD,IAAe,IAAI,CAAC,IAAL,CAAU,MAAV,CAAA,KAAqB,IAAC,CAAA,UAAxC;AACI,YAAM,qCAAN,CADJ;KAVA;AAcA,IAAA,IAAmC,CAAA,IAAE,CAAA,UAArC;AAAA,MAAA,IAAC,CAAA,UAAD,GAAc,IAAI,CAAC,IAAL,CAAU,MAAV,CAAd,CAAA;KAdA;AAAA,IAeA,IAAC,CAAA,WAAY,CAAA,EAAA,CAAb,GAAmB,MAfnB,CAAA;WAiBA,GAlBY;EAAA,CA/ChB,CAAA;;oBAAA;;IALJ,CAAA"
 }
\ No newline at end of file
diff --git a/js/client.js b/js/client.js
index 50b9463..f39b793 100644
--- a/js/client.js
+++ b/js/client.js
@@ -1,11 +1,9 @@
-var Client, debug, express, _;
+var Client, debug, express;
 
 debug = require("debug")("prometheus-client");
 
 express = require("express");
 
-_ = require("underscore");
-
 module.exports = Client = (function() {
   Client._globalRegistry = null;
 
diff --git a/js/client.js.map b/js/client.js.map
index cc073e7..7c0d624 100644
--- a/js/client.js.map
+++ b/js/client.js.map
@@ -6,5 +6,5 @@
     "client.coffee"
   ],
   "names": [],
-  "mappings": "AAAA,IAAA,yBAAA;;AAAA,KAAA,GAAQ,OAAA,CAAQ,OAAR,CAAA,CAAiB,mBAAjB,CAAR,CAAA;;AAAA,OACA,GAAU,OAAA,CAAQ,SAAR,CADV,CAAA;;AAAA,CAEA,GAAI,OAAA,CAAQ,YAAR,CAFJ,CAAA;;AAAA,MAIM,CAAC,OAAP,GAAuB;AACnB,EAAA,MAAC,CAAA,eAAD,GAAoB,IAApB,CAAA;;AAAA,EAEA,MAAC,CAAA,KAAD,GAAY,OAAA,CAAQ,SAAR,CAFZ,CAAA;;AAAA,EAGA,MAAC,CAAA,OAAD,GAAY,OAAA,CAAQ,WAAR,CAHZ,CAAA;;AAAA,EAIA,MAAC,CAAA,QAAD,GAAY,OAAA,CAAQ,YAAR,CAJZ,CAAA;;AAMa,EAAA,gBAAC,IAAD,GAAA;AACT,IAAA,IAAC,CAAA,QAAD,mBAAY,IAAI,CAAE,kBAAN,IAAkB,CAAC,MAAM,CAAC,oBAAP,MAAM,CAAC,kBAAoB,GAAA,CAAA,MAAU,CAAC,SAAvC,CAA9B,CADS;EAAA,CANb;;AAAA,mBAWA,QAAA,GAAU,SAAC,MAAD,GAAA;WACN,IAAC,CAAA,QAAQ,CAAC,QAAV,CAAmB,MAAnB,EADM;EAAA,CAXV,CAAA;;AAAA,mBAgBA,WAAA,GAAa,SAAA,GAAA;WACT,IAAC,CAAA,QAAQ,CAAC,YADD;EAAA,CAhBb,CAAA;;AAAA,mBAqBA,UAAA,GAAY,SAAC,IAAD,GAAA;WACR,IAAC,CAAA,QAAD,CAAc,IAAA,MAAM,CAAC,OAAP,CAAe,IAAf,CAAd,EADQ;EAAA,CArBZ,CAAA;;AAAA,mBA0BA,QAAA,GAAU,SAAC,IAAD,GAAA;WACN,IAAC,CAAA,QAAD,CAAc,IAAA,MAAM,CAAC,KAAP,CAAa,IAAb,CAAd,EADM;EAAA,CA1BV,CAAA;;AAAA,mBA+BA,MAAA,GAAQ,SAAC,IAAD,GAAA;AACJ,QAAA,GAAA;AAAA,IAAA,GAAA,GAAM,OAAA,CAAA,CAAN,CAAA;AAAA,IACA,GAAG,CAAC,GAAJ,CAAQ,UAAR,EAAoB,IAAC,CAAA,QAAQ,CAAC,WAA9B,CADA,CAAA;AAAA,IAEA,GAAG,CAAC,MAAJ,CAAW,IAAX,EAAiB,SAAA,GAAA;aACb,KAAA,CAAO,eAAA,GAAe,IAAtB,EADa;IAAA,CAAjB,CAFA,CAAA;AAAA,IAIA,GAAG,CAAC,EAAJ,CAAO,OAAP,EAAgB,SAAC,GAAD,GAAA;aACZ,KAAA,CAAO,uBAAA,GAAuB,GAA9B,EADY;IAAA,CAAhB,CAJA,CAAA;WAOA,IARI;EAAA,CA/BR,CAAA;;gBAAA;;IALJ,CAAA"
+  "mappings": "AAAA,IAAA,sBAAA;;AAAA,KAAA,GAAQ,OAAA,CAAQ,OAAR,CAAA,CAAiB,mBAAjB,CAAR,CAAA;;AAAA,OACA,GAAU,OAAA,CAAQ,SAAR,CADV,CAAA;;AAAA,MAGM,CAAC,OAAP,GAAuB;AACnB,EAAA,MAAC,CAAA,eAAD,GAAoB,IAApB,CAAA;;AAAA,EAEA,MAAC,CAAA,KAAD,GAAY,OAAA,CAAQ,SAAR,CAFZ,CAAA;;AAAA,EAGA,MAAC,CAAA,OAAD,GAAY,OAAA,CAAQ,WAAR,CAHZ,CAAA;;AAAA,EAIA,MAAC,CAAA,QAAD,GAAY,OAAA,CAAQ,YAAR,CAJZ,CAAA;;AAMa,EAAA,gBAAC,IAAD,GAAA;AACT,IAAA,IAAC,CAAA,QAAD,mBAAY,IAAI,CAAE,kBAAN,IAAkB,CAAC,MAAM,CAAC,oBAAP,MAAM,CAAC,kBAAoB,GAAA,CAAA,MAAU,CAAC,SAAvC,CAA9B,CADS;EAAA,CANb;;AAAA,mBAWA,QAAA,GAAU,SAAC,MAAD,GAAA;WACN,IAAC,CAAA,QAAQ,CAAC,QAAV,CAAmB,MAAnB,EADM;EAAA,CAXV,CAAA;;AAAA,mBAgBA,WAAA,GAAa,SAAA,GAAA;WACT,IAAC,CAAA,QAAQ,CAAC,YADD;EAAA,CAhBb,CAAA;;AAAA,mBAqBA,UAAA,GAAY,SAAC,IAAD,GAAA;WACR,IAAC,CAAA,QAAD,CAAc,IAAA,MAAM,CAAC,OAAP,CAAe,IAAf,CAAd,EADQ;EAAA,CArBZ,CAAA;;AAAA,mBA0BA,QAAA,GAAU,SAAC,IAAD,GAAA;WACN,IAAC,CAAA,QAAD,CAAc,IAAA,MAAM,CAAC,KAAP,CAAa,IAAb,CAAd,EADM;EAAA,CA1BV,CAAA;;AAAA,mBA+BA,MAAA,GAAQ,SAAC,IAAD,GAAA;AACJ,QAAA,GAAA;AAAA,IAAA,GAAA,GAAM,OAAA,CAAA,CAAN,CAAA;AAAA,IACA,GAAG,CAAC,GAAJ,CAAQ,UAAR,EAAoB,IAAC,CAAA,QAAQ,CAAC,WAA9B,CADA,CAAA;AAAA,IAEA,GAAG,CAAC,MAAJ,CAAW,IAAX,EAAiB,SAAA,GAAA;aACb,KAAA,CAAO,eAAA,GAAe,IAAtB,EADa;IAAA,CAAjB,CAFA,CAAA;AAAA,IAIA,GAAG,CAAC,EAAJ,CAAO,OAAP,EAAgB,SAAC,GAAD,GAAA;aACZ,KAAA,CAAO,uBAAA,GAAuB,GAA9B,EADY;IAAA,CAAhB,CAJA,CAAA;WAOA,IARI;EAAA,CA/BR,CAAA;;gBAAA;;IAJJ,CAAA"
 }
\ No newline at end of file
diff --git a/package.json b/package.json
index 3209346..4240ad0 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,6 @@
         "node": ">=0.10.0"
     },
     "dependencies": {
-        "underscore":     "~1.7.0",
         "debug":          "~2.1.2",
         "express":        "~4.12.3",
         "object-hash":    "~0.5.0"
diff --git a/src/base_metric.coffee b/src/base_metric.coffee
index 75c4f22..27ec0d3 100644
--- a/src/base_metric.coffee
+++ b/src/base_metric.coffee
@@ -1,5 +1,4 @@
 debug   = require("debug")("prometheus-client:metric")
-_       = require "underscore"
 hash    = require "object-hash"
 
 module.exports = class BaseMetric
@@ -21,7 +20,7 @@ module.exports = class BaseMetric
         throw "Name is required" if !@name
         throw "Help is required" if !@help
 
-        @_full_name     = _.compact([ @namespace, @subsystem, @name ]).join("_")
+        @_full_name     = [ @namespace, @subsystem, @name ].filter((s)->s).join("_")
 
     #----------
 
@@ -59,7 +58,7 @@ module.exports = class BaseMetric
         # Validate each label key
         for k,v of labels
             throw "Label #{k} must not start with __" if /^__/.test(k)
-            throw "Label #{k} is reserved" if _(['instance','job']).contains(k)
+            throw "Label #{k} is reserved" if 'instance'==k || 'job'==k
 
         # Validate that the set of keys is correct
         if @_labelKeys && hash.keys(labels) != @_labelKeys
@@ -69,4 +68,4 @@ module.exports = class BaseMetric
         @_labelKeys = hash.keys(labels) if !@_labelKeys
         @_labelCache[lh] = labels
 
-        lh
\ No newline at end of file
+        lh
diff --git a/src/client.coffee b/src/client.coffee
index 69b408d..ba0bbfc 100644
--- a/src/client.coffee
+++ b/src/client.coffee
@@ -1,6 +1,5 @@
 debug = require("debug")("prometheus-client")
 express = require "express"
-_ = require "underscore"
 
 module.exports = class Client
     @_globalRegistry:   null
@@ -46,4 +45,4 @@ module.exports = class Client
 
     #----------
 
-    #----------
\ No newline at end of file
+    #----------
diff --git a/test/common.coffee b/test/common.coffee
index 2e8794f..dc59fd6 100644
--- a/test/common.coffee
+++ b/test/common.coffee
@@ -2,4 +2,4 @@ chai            = require "chai"
 global.expect   = chai.expect
 
 path = require "path"
-global.$src     = (module) -> require path.resolve(__dirname,"..","lib",module)
\ No newline at end of file
+global.$src     = (module) -> require path.resolve(__dirname,"..","js",module)
diff --git a/test/metrics.coffee b/test/metrics.coffee
new file mode 100644
index 0000000..08a9a5d
--- /dev/null
+++ b/test/metrics.coffee
@@ -0,0 +1,71 @@
+Prometheus = $src "client"
+Registry  = $src "registry"
+
+describe 'Counter', ->
+    client = null
+    counter = null
+    before ->
+        client = new Prometheus(registry: new Registry)
+
+        counter = client.newCounter({
+            namespace: "counter_test",
+            name: "elapsed_counters_total",
+            help: "The number of counter intervals that have elapsed."
+        })
+
+        counter.increment(period:"1sec")
+        counter.increment(period:"2sec")
+
+    it 'should generate some counter metrics', ->
+        lineCount = 0
+        lines=[
+            '# HELP counter_test_elapsed_counters_total The number of counter intervals that have elapsed.\n' +
+            '# TYPE counter_test_elapsed_counters_total counter\n',
+            'counter_test_elapsed_counters_total{period="1sec"} 1\n',
+            'counter_test_elapsed_counters_total{period="2sec"} 1\n'
+        ]
+        mockRes =
+            writeHead: (statusCode, header) ->
+                expect(statusCode).to.equal(200)
+                expect(header).to.deep.equal('content-type': 'text/plain; version=0.0.4')
+            write: (line) ->
+                expect(line).to.equal lines[lineCount]
+                lineCount++
+            end: () ->
+                expect(lineCount).to.equal lines.length
+
+        client.metricsFunc()(null, mockRes)
+
+describe 'Gauge', ->
+    client = null
+    gauge = null
+    before ->
+        client = new Prometheus(registry: new Registry)
+
+        gauge = client.newGauge({
+            namespace: "gauge_test",
+            name: "fixed_test_number",
+            help: "A few test numbers we set."
+        });
+
+        gauge.set({ period: "1sec" }, 123);
+        gauge.set({ period: "1sec" }, 456);
+
+    it 'should generate some gauge metrics', ->
+        lineCount = 0
+        lines=[
+            '# HELP gauge_test_fixed_test_number A few test numbers we set.\n' +
+            '# TYPE gauge_test_fixed_test_number gauge\n',
+            'gauge_test_fixed_test_number{period="1sec"} 456\n'
+        ]
+        mockRes =
+            writeHead: (statusCode, header) ->
+                expect(statusCode).to.equal(200)
+                expect(header).to.deep.equal('content-type': 'text/plain; version=0.0.4')
+            write: (line) ->
+                expect(line).to.equal lines[lineCount]
+                lineCount++
+            end: () ->
+                expect(lineCount).to.equal lines.length
+
+        client.metricsFunc()(null, mockRes)