feat(httpclient): Added test server helper (#323)

Author: ekkinox

httpclient/README.md

@@ -9,15 +9,14 @@
 > Http client module based on [net/http](https://pkg.go.dev/net/http).
 
 <!-- TOC -->
-
 * [Installation](#installation)
 * [Documentation](#documentation)
-	* [Requests](#requests)
-	* [Transports](#transports)
-		* [BaseTransport](#basetransport)
-		* [LoggerTransport](#loggertransport)
-		* [MetricsTransport](#metricstransport)
-
+  * [Requests](#requests)
+  * [Transports](#transports)
+    * [BaseTransport](#basetransport)
+    * [LoggerTransport](#loggertransport)
+    * [MetricsTransport](#metricstransport)
+  * [Testing](#testing)
 <!-- TOC -->
 
 ## Installation
@@ -224,4 +223,96 @@ map[string]string{
 
 Then if the request path is `/foo/1/bar?page=2`, the metric path label will be masked with `/foo/{fooId}/bar?page={pageId}`.
 
+### Testing
+
+This module provides a [httpclienttest.NewTestHTTPServer()](httpclienttest/server.go) helper for testing your clients against a test server, that allows you:
+
+- to define test HTTP roundtrips: a couple of test aware functions to define the request and the response behavior
+- to configure several test HTTP roundtrips if you need to test successive calls
+
+To use it:
+
+```go
+package main_test
+
+import (
+	"errors"
+	"net/http"
+	"testing"
+
+	"github.com/ankorstore/yokai/httpclient"
+	"github.com/ankorstore/yokai/httpclient/httpclienttest"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHTTPClient(t *testing.T) {
+	t.Parallel()
+
+	// client
+	client, err := httpclient.NewDefaultHttpClientFactory().Create()
+	assert.NoError(t, err)
+
+	// test server preparation
+	testServer := httpclienttest.NewTestHTTPServer(
+		t,
+		// configures a roundtrip for the 1st client call
+		httpclienttest.WithTestHTTPRoundTrip(
+			// func to configure / assert on the client request
+			func(tb testing.TB, req *http.Request) error {
+				tb.Helper()
+
+				// performs some assertions
+				assert.Equal(tb, "/foo", req.URL.Path)
+
+				// returning an error here will make the test fail, if needed
+				return nil
+			},
+			// func to configure / assert on the response for the client
+			func(tb testing.TB, w http.ResponseWriter) error {
+				tb.Helper()
+
+				// prepares the response for the client
+				w.Header.Set("foo", "bar")
+
+				// performs some assertions
+				assert.Equal(tb, "bar", w.Header.Get("foo"))
+
+				// returning an error here will make the test fail, if needed
+				return nil
+			},
+		),
+		// configures a roundtrip for the 2nd client call
+		httpclienttest.WithTestHTTPRoundTrip(
+			// func to configure / assert on the client request
+			func(tb testing.TB, req *http.Request) error {
+				tb.Helper()
+
+				assert.Equal(tb, "/bar", req.URL.Path)
+				
+				return nil
+			},
+			// func to configure / assert on the response for the client
+			func(tb testing.TB, w http.ResponseWriter) error {
+				tb.Helper()
+
+				w.WriteHeader(http.StatusInternalServerError)
+				
+				return nil
+			},
+		),
+	)
+
+	// 1st client call
+	resp, err := client.Get(testServer.URL + "/foo")
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+	assert.Equal(t, "bar", resp.Header.Get("foo"))
+
+	// 2nd client call
+	resp, err = client.Get(testServer.URL + "/bar")
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusInternalServerError, resp.StatusCode)
+}
+```
 
+You can find more complete examples in the [tests](httpclienttest/server_test.go).

httpclient/httpclienttest/option.go

@@ -0,0 +1,22 @@
+package httpclienttest
+
+type TestHTTPServerOptions struct {
+	RoundtripsStack []TestHTTPRoundTrip
+}
+
+func DefaultTestHTTPServerOptions() TestHTTPServerOptions {
+	return TestHTTPServerOptions{
+		RoundtripsStack: []TestHTTPRoundTrip{},
+	}
+}
+
+type TestHTTPServerOptionFunc func(o *TestHTTPServerOptions)
+
+func WithTestHTTPRoundTrip(reqFunc TestHTTPRequestFunc, responseFunc TestHTTPResponseFunc) TestHTTPServerOptionFunc {
+	return func(o *TestHTTPServerOptions) {
+		o.RoundtripsStack = append(o.RoundtripsStack, TestHTTPRoundTrip{
+			RequestFunc:  reqFunc,
+			ResponseFunc: responseFunc,
+		})
+	}
+}

httpclient/httpclienttest/option_test.go

@@ -0,0 +1,32 @@
+package httpclienttest_test
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/ankorstore/yokai/httpclient/httpclienttest"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTestHTTPServerOptions(t *testing.T) {
+	t.Parallel()
+
+	defaultOptions := httpclienttest.DefaultTestHTTPServerOptions()
+	assert.Len(t, defaultOptions.RoundtripsStack, 0)
+
+	option := httpclienttest.WithTestHTTPRoundTrip(
+		func(tb testing.TB, req *http.Request) error {
+			tb.Helper()
+
+			return nil
+		},
+		func(tb testing.TB, w http.ResponseWriter) error {
+			tb.Helper()
+
+			return nil
+		},
+	)
+
+	option(&defaultOptions)
+	assert.Len(t, defaultOptions.RoundtripsStack, 1)
+}

httpclient/httpclienttest/server.go

@@ -0,0 +1,60 @@
+package httpclienttest
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type TestHTTPRequestFunc func(tb testing.TB, req *http.Request) error
+type TestHTTPResponseFunc func(tb testing.TB, w http.ResponseWriter) error
+
+type TestHTTPRoundTrip struct {
+	RequestFunc  TestHTTPRequestFunc
+	ResponseFunc TestHTTPResponseFunc
+}
+
+func NewTestHTTPServer(tb testing.TB, options ...TestHTTPServerOptionFunc) *httptest.Server {
+	tb.Helper()
+
+	var mu sync.Mutex
+
+	serverOptions := DefaultTestHTTPServerOptions()
+	for _, opt := range options {
+		opt(&serverOptions)
+	}
+
+	if len(serverOptions.RoundtripsStack) == 0 {
+		tb.Error("test HTTP server: empty roundtrips stack")
+
+		return nil
+	}
+
+	stackPosition := 0
+
+	return httptest.NewServer(
+		http.HandlerFunc(
+			func(w http.ResponseWriter, r *http.Request) {
+				mu.Lock()
+				defer mu.Unlock()
+
+				if stackPosition >= len(serverOptions.RoundtripsStack) {
+					tb.Error("test HTTP server: roundtrips stack exhausted")
+
+					return
+				}
+
+				err := serverOptions.RoundtripsStack[stackPosition].RequestFunc(tb, r)
+				assert.NoError(tb, err)
+
+				err = serverOptions.RoundtripsStack[stackPosition].ResponseFunc(tb, w)
+				assert.NoError(tb, err)
+
+				stackPosition++
+			},
+		),
+	)
+}