Add Gin compatible middleware

.github/workflows/go.yml → .github/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: Go
+name: CI
 on: [push]
 jobs:
   test:

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- Gin compatible middleware.
+
 ## [0.4.0] - 2019-03-27
 
 ### Breaking changes

Readme.md

@@ -41,6 +41,7 @@ The middleware is mainly focused to be compatible with Go std library using http
 - [Negroni][negroni-example]
 - [httprouter][httprouter-example]
 - [go-restful][gorestful-example]
+- [Gin][gin-example]
 
 ## Getting Started
 
@@ -202,7 +203,7 @@ BenchmarkMiddlewareHandler/benchmark_with_grouped_status_code.-4      	 1000000
 BenchmarkMiddlewareHandler/benchmark_with_predefined_handler_ID-4     	 1000000	      1258 ns/op	     256 B/op	       6 allocs/op
 ```
 
-[github-actions-image]: https://github.com/slok/go-http-metrics/workflows/Go/badge.svg
+[github-actions-image]: https://github.com/slok/go-http-metrics/workflows/CI/badge.svg
 [github-actions-url]: https://github.com/slok/go-http-metrics/actions
 [goreport-image]: https://goreportcard.com/badge/github.com/slok/go-http-metrics
 [goreport-url]: https://goreportcard.com/report/github.com/slok/go-http-metrics
@@ -217,5 +218,6 @@ BenchmarkMiddlewareHandler/benchmark_with_predefined_handler_ID-4     	 1000000
 [negroni-example]: examples/negroni
 [httprouter-example]: examples/httprouter
 [gorestful-example]: examples/gorestful
+[gin-example]: examples/gin
 [prometheus-recorder]: metrics/prometheus
 [opencensus-recorder]: metrics/opencensus

examples/gin/main.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/gin-gonic/gin"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
+	"github.com/slok/go-http-metrics/middleware"
+	ginmiddleware "github.com/slok/go-http-metrics/middleware/gin"
+)
+
+const (
+	srvAddr     = ":8080"
+	metricsAddr = ":8081"
+)
+
+func main() {
+	// Create our middleware.
+	mdlw := middleware.New(middleware.Config{
+		Recorder: metrics.NewRecorder(metrics.Config{}),
+	})
+
+	// Create Gin engine and global middleware.
+	engine := gin.New()
+	engine.Use(ginmiddleware.Handler("", mdlw))
+
+	// Add our handler.
+	engine.GET("/", func(c *gin.Context) {
+		c.String(http.StatusOK, "Hello world")
+	})
+	engine.GET("/wrong", func(c *gin.Context) {
+		c.String(http.StatusTooManyRequests, "oops")
+	})
+
+	// Serve our handler.
+	go func() {
+		log.Printf("server listening at %s", srvAddr)
+		if err := http.ListenAndServe(srvAddr, engine); err != nil {
+			log.Panicf("error while serving: %s", err)
+		}
+	}()
+
+	// Serve our metrics.
+	go func() {
+		log.Printf("metrics listening at %s", metricsAddr)
+		if err := http.ListenAndServe(metricsAddr, promhttp.Handler()); err != nil {
+			log.Panicf("error while serving metrics: %s", err)
+		}
+	}()
+
+	// Wait until some signal is captured.
+	sigC := make(chan os.Signal, 1)
+	signal.Notify(sigC, syscall.SIGTERM, syscall.SIGINT)
+	<-sigC
+}

examples/gorestful/main.go

@@ -46,7 +46,7 @@ func main() {
 	// Serve our handler.
 	go func() {
 		log.Printf("server listening at %s", srvAddr)
-		if err := http.ListenAndServe(":8080", c); err != nil {
+		if err := http.ListenAndServe(srvAddr, c); err != nil {
 			log.Panicf("error while serving: %s", err)
 		}
 	}()

go.mod

@@ -3,9 +3,12 @@ module github.com/slok/go-http-metrics
 require (
 	contrib.go.opencensus.io/exporter/prometheus v0.1.0
 	github.com/emicklei/go-restful v2.9.6+incompatible
+	github.com/gin-gonic/gin v1.5.0
 	github.com/julienschmidt/httprouter v1.2.0
 	github.com/prometheus/client_golang v1.0.0
-	github.com/stretchr/testify v1.3.0
+	github.com/stretchr/testify v1.4.0
 	github.com/urfave/negroni v1.0.0
 	go.opencensus.io v0.22.0
 )
+
+go 1.13

go.sum

@@ -14,8 +14,16 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/emicklei/go-restful v2.9.6+incompatible h1:tfrHha8zJ01ywiOEC1miGY8st1/igzWB8OmvPgoYX7w=
 github.com/emicklei/go-restful v2.9.6+incompatible/go.mod h1:otzb+WCGbkyDHkqmQmT5YD2WR4BBwUdeQoFo8l/7tVs=
+github.com/gin-contrib/sse v0.1.0 h1:Y/yl/+YNO8GZSjAhjMsSuLt29uWRFHdHYUb5lYOV9qE=
+github.com/gin-contrib/sse v0.1.0/go.mod h1:RHrZQHXnP2xjPF+u1gW/2HnVO7nvIa9PG3Gm+fLHvGI=
+github.com/gin-gonic/gin v1.5.0 h1:fi+bqFAx/oLK54somfCtEZs9HeH1LHVoEPUgARpTqyc=
+github.com/gin-gonic/gin v1.5.0/go.mod h1:Nd6IXA8m5kNZdNEHMBd93KT+mdY3+bewLgRvmCsR2Do=
 github.com/go-kit/kit v0.8.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
 github.com/go-logfmt/logfmt v0.3.0/go.mod h1:Qt1PoO58o5twSAckw1HlFXLmHsOX5/0LbT9GBnD5lWE=
+github.com/go-playground/locales v0.12.1 h1:2FITxuFt/xuCNP1Acdhv62OzaCiviiE4kotfhkmOqEc=
+github.com/go-playground/locales v0.12.1/go.mod h1:IUMDtCfWo/w/mtMfIE/IG2K+Ey3ygWanZIBtBW0W2TM=
+github.com/go-playground/universal-translator v0.16.0 h1:X++omBR/4cE2MNg91AoC3rmGrCjJ8eAeUP/K/EKx4DM=
+github.com/go-playground/universal-translator v0.16.0/go.mod h1:1AnU7NaIRDWWzGEKwgtJRd2xk99HeFyHw3yid4rvQIY=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
@@ -24,24 +32,34 @@ github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.3.1 h1:YF8+flBXS5eO826T4nzqPrxfhQThhXl0YzfuUPu4SBg=
 github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.3.2 h1:6nsPYzhq5kReh6QImI3k5qWzO4PEbvbIW2cwSfR/6xs=
+github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 github.com/google/go-cmp v0.3.0 h1:crn/baboCvb5fXaQ0IJ1SGTsTVrWpDsCWC8EGETZijY=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/hashicorp/golang-lru v0.5.0 h1:CL2msUPvZTLb5O648aiLNJw3hnBxN2+1Jq8rCOH9wdo=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1 h1:0hERBMJE1eitiLkihrMvRVBYAkpHzc/J3QdDN+dAcgU=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/json-iterator/go v1.1.6 h1:MrUvLMLTMxbqFJ9kzlvat/rYZqZnW3u4wkLzWTaFwKs=
 github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
+github.com/json-iterator/go v1.1.7/go.mod h1:KdQUCv79m/52Kvf8AW2vK1V8akMuk1QjK/uOdHXbAo4=
 github.com/julienschmidt/httprouter v1.2.0 h1:TDTW5Yz1mjftljbcKqRcrYhd4XeOoI98t+9HbQbYf7g=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
+github.com/leodido/go-urn v1.1.0 h1:Sm1gr51B1kKyfD2BlRcLSiEkffoG96g6TPv6eRoEiB8=
+github.com/leodido/go-urn v1.1.0/go.mod h1:+cyI34gQWZcE1eQU7NVgKkkzdXDQHr1dBMtdAPozLkw=
+github.com/mattn/go-isatty v0.0.9 h1:d5US/mDsogSGW37IV293h//ZFaeajb69h+EHFsv2xGg=
+github.com/mattn/go-isatty v0.0.9/go.mod h1:YNRxwqDuOph6SZLI9vUUz6OYw3QyUt7WiY2yME+cCiQ=
 github.com/matttproud/golang_protobuf_extensions v1.0.1 h1:4hp9jkHxhMHkqkrB3Ix0jegS5sx/RkqARlsWZ6pIwiU=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
+github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
+github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
 github.com/modern-go/reflect2 v1.0.1 h1:9f412s+6RmYXLWZSEzVVgPGK7C2PphHj5RJrvfx9AWI=
 github.com/modern-go/reflect2 v1.0.1/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
@@ -71,6 +89,12 @@ github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/ugorji/go v1.1.7 h1:/68gy2h+1mWMrwZFeD1kQialdSzAb432dtpeJ42ovdo=
+github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=
+github.com/ugorji/go/codec v1.1.7 h1:2SvQaVZ1ouYrrKKwoSk2pzd4A9evlKJb9oTL+OaLUSs=
+github.com/ugorji/go/codec v1.1.7/go.mod h1:Ax+UKWsSmolVDwsd+7N3ZtXu+yMGCf907BLYF3GoBXY=
 github.com/urfave/negroni v1.0.0 h1:kIimOitoypq34K7TG7DUaJ9kq/N4Ofuwi1sjz0KipXc=
 github.com/urfave/negroni v1.0.0/go.mod h1:Meg73S6kFm/4PpbYdq35yYWoCZ9mS/YSx+lKnmiohz4=
 go.opencensus.io v0.21.0 h1:mU6zScU4U1YAFPHEHYk+3JC4SY7JxgkqS10ZOSyksNg=
@@ -105,6 +129,7 @@ golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a h1:1BGLXjeY4akVXGgbC9HugT3Jv
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190502145724-3ef323f4f1fd h1:r7DufRZuZbWB7j439YfAzP8RPDa9unLkpwQKUYbIMPI=
 golang.org/x/sys v0.0.0-20190502145724-3ef323f4f1fd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
@@ -121,6 +146,11 @@ google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiq
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/go-playground/assert.v1 v1.2.1/go.mod h1:9RXL0bg/zibRAgZUYszZSwO/z8Y/a8bDuhia5mkpMnE=
+gopkg.in/go-playground/validator.v9 v9.29.1 h1:SvGtYmN60a5CVKTOzMSyfzWDeZRxRuGvRQyEAKbw1xc=
+gopkg.in/go-playground/validator.v9 v9.29.1/go.mod h1:+c9/zcJMFNgbLvly1L1V+PpxWdVbfP1avr/N00E2vyQ=
 gopkg.in/yaml.v2 v2.2.1 h1:mUhvW9EsL+naU5Q3cakzfE91YhliOondGd6ZrsDBHQE=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=

middleware/gin/example_test.go

@@ -0,0 +1,41 @@
+package gin_test
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+
+	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
+	"github.com/slok/go-http-metrics/middleware"
+	ginmiddleware "github.com/slok/go-http-metrics/middleware/gin"
+)
+
+// GinMiddleware shows how you would create a default middleware factory and use it
+// to create a Gin compatible middleware.
+func Example_ginMiddleware() {
+	// Create our middleware factory with the default settings.
+	mdlw := middleware.New(middleware.Config{
+		Recorder: metrics.NewRecorder(metrics.Config{}),
+	})
+
+	// Create our gin instance.
+	engine := gin.New()
+
+	// Add our handler and middleware
+	h := func(c *gin.Context) {
+		c.String(http.StatusOK, "Hello world")
+	}
+	engine.GET("/", ginmiddleware.Handler("", mdlw), h)
+
+	// Serve metrics from the default prometheus registry.
+	log.Printf("serving metrics at: %s", ":8081")
+	go http.ListenAndServe(":8081", promhttp.Handler())
+
+	// Serve our handler.
+	log.Printf("listening at: %s", ":8080")
+	if err := http.ListenAndServe(":8080", engine); err != nil {
+		log.Panicf("error while serving: %s", err)
+	}
+}

middleware/gin/gin.go

@@ -0,0 +1,52 @@
+// Package gin is a helper package to get a gin compatible
+// handler/middleware from the standard net/http Middleware factory.
+package gin
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+
+	"github.com/slok/go-http-metrics/middleware"
+)
+
+// Handler returns a Gin compatible middleware from a Middleware factory instance.
+// The first handlerID argument is the same argument passed on Middleware.Handler method.
+func Handler(handlerID string, m middleware.Middleware) gin.HandlerFunc {
+	// Create a dummy handler to wrap the middleware chain of Gin, this way Middleware
+	// interface can wrap the Gin chain.
+	return func(c *gin.Context) {
+		h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			c.Writer = &ginResponseWriter{
+				ResponseWriter: c.Writer,
+				middlewareRW:   w,
+			}
+			c.Next()
+		})
+		m.Handler(handlerID, h).ServeHTTP(c.Writer, c.Request)
+	}
+}
+
+// ginResponseWriter is a helper type that intercepts the middleware ResponseWriter
+// interceptor.
+// This is required because gin's context Writer (c.Writer) is a gin.ResponseWriter
+// interface and we can't access to the internal object http.ResponseWriter, so
+// we already know that our middleware intercepts the regular http.ResponseWriter,
+// and doesn't change anything, just intercepts to read information. So in order to
+// get this information on our interceptor we create a gin.ResponseWriter implementation
+// that will call the real gin.Context.Writer and our interceptor. This way Gin gets the
+// information and our interceptor also.
+type ginResponseWriter struct {
+	middlewareRW http.ResponseWriter
+	gin.ResponseWriter
+}
+
+func (w *ginResponseWriter) WriteHeader(statusCode int) {
+	w.middlewareRW.WriteHeader(statusCode)
+	w.ResponseWriter.WriteHeader(statusCode)
+}
+
+func (w *ginResponseWriter) Write(p []byte) (int, error) {
+	w.middlewareRW.Write(p)
+	return w.ResponseWriter.Write(p)
+}

middleware/gin/gin_test.go

@@ -0,0 +1,71 @@
+package gin_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+
+	mmetrics "github.com/slok/go-http-metrics/internal/mocks/metrics"
+	"github.com/slok/go-http-metrics/middleware"
+	ginmiddleware "github.com/slok/go-http-metrics/middleware/gin"
+)
+
+func getTestHandler(statusCode int) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		c.String(statusCode, "Hello world")
+	}
+}
+
+func TestMiddlewareIntegration(t *testing.T) {
+	tests := []struct {
+		name          string
+		handlerID     string
+		statusCode    int
+		req           *http.Request
+		config        middleware.Config
+		expHandlerID  string
+		expMethod     string
+		expStatusCode string
+	}{
+		{
+			name:          "A default HTTP middleware should call the recorder to measure.",
+			statusCode:    http.StatusAccepted,
+			req:           httptest.NewRequest(http.MethodPost, "/test", nil),
+			expHandlerID:  "/test",
+			expMethod:     http.MethodPost,
+			expStatusCode: "202",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			assert := assert.New(t)
+
+			// Mocks.
+			mr := &mmetrics.Recorder{}
+			mr.On("ObserveHTTPRequestDuration", mock.Anything, test.expHandlerID, mock.Anything, test.expMethod, test.expStatusCode).Once()
+			mr.On("ObserveHTTPResponseSize", mock.Anything, test.expHandlerID, mock.Anything, test.expMethod, test.expStatusCode).Once()
+			mr.On("AddInflightRequests", mock.Anything, test.expHandlerID, 1).Once()
+			mr.On("AddInflightRequests", mock.Anything, test.expHandlerID, -1).Once()
+
+			// Create our instance with the middleware.
+			mdlw := middleware.New(middleware.Config{Recorder: mr})
+			engine := gin.New()
+			engine.POST("/test",
+				ginmiddleware.Handler("", mdlw),
+				getTestHandler(test.statusCode))
+
+			// Make the request.
+			resp := httptest.NewRecorder()
+			engine.ServeHTTP(resp, test.req)
+
+			// Check.
+			mr.AssertExpectations(t)
+			assert.Equal(test.statusCode, resp.Result().StatusCode)
+		})
+	}
+}