test: allow usage of httpmock in tests (#2576)

* add test case

* add flag for default transport

* Update go.mod

* Update go.sum

* fix spaces

* fix format

* Update http_test.go

* Update http_test.go

* Update http_test.go

* Update http_test.go

* Update http_test.go

go.mod

@@ -38,6 +38,7 @@ require (
 	github.com/hashicorp/vault/api v1.0.4
 	github.com/huandu/xstrings v1.3.2 // indirect
 	github.com/imdario/mergo v0.3.11 // indirect
+	github.com/jarcoal/httpmock v1.0.6
 	github.com/magiconair/properties v1.8.4
 	github.com/mailru/easyjson v0.7.6 // indirect
 	github.com/mitchellh/mapstructure v1.3.3 // indirect

go.sum

@@ -536,6 +536,8 @@ github.com/iris-contrib/blackfriday v2.0.0+incompatible/go.mod h1:UzZ2bDEoaSGPbk
 github.com/iris-contrib/go.uuid v2.0.0+incompatible/go.mod h1:iz2lgM/1UnEf1kP0L/+fafWORmlnuysV2EMP8MW+qe0=
 github.com/iris-contrib/i18n v0.0.0-20171121225848-987a633949d0/go.mod h1:pMCz62A0xJL6I+umB2YTlFRwWXaDFA0jy+5HzGiJjqI=
 github.com/iris-contrib/schema v0.0.1/go.mod h1:urYA3uvUNG1TIIjOSCzHr9/LmbQo8LrOcOqfqxa4hXw=
+github.com/jarcoal/httpmock v1.0.6 h1:e81vOSexXU3mJuJ4l//geOmKIt+Vkxerk1feQBC8D0g=
+github.com/jarcoal/httpmock v1.0.6/go.mod h1:ATjnClrvW/3tijVmpL/va5Z3aAyGvqU3gCT8nX0Txik=
 github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 h1:BQSFePA1RWJOlocH6Fxy8MmwDt+yVQYULKfN0RoTN8A=
 github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99/go.mod h1:1lJo3i6rXxKeerYnT8Nvf0QmHCRC1n8sfWVwXF2Frvo=
 github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=

pkg/http/http.go

@@ -36,6 +36,7 @@ type Client struct {
 	cookieJar                 http.CookieJar
 	doLogRequestBodyOnDebug   bool
 	doLogResponseBodyOnDebug  bool
+	useDefaultTransport       bool
 }
 
 // ClientOptions defines the options to be set on the client
@@ -57,6 +58,7 @@ type ClientOptions struct {
 	CookieJar                 http.CookieJar
 	DoLogRequestBodyOnDebug   bool
 	DoLogResponseBodyOnDebug  bool
+	UseDefaultTransport       bool
 }
 
 // TransportWrapper is a wrapper for central logging capabilities
@@ -196,6 +198,7 @@ func (c *Client) SendRequest(method, url string, body io.Reader, header http.Hea
 func (c *Client) SetOptions(options ClientOptions) {
 	c.doLogRequestBodyOnDebug = options.DoLogRequestBodyOnDebug
 	c.doLogResponseBodyOnDebug = options.DoLogResponseBodyOnDebug
+	c.useDefaultTransport = options.UseDefaultTransport
 	c.transportTimeout = options.TransportTimeout
 	c.transportSkipVerification = options.TransportSkipVerification
 	c.maxRequestDuration = options.MaxRequestDuration
@@ -237,14 +240,18 @@ func (c *Client) initialize() *http.Client {
 		retryClient := retryablehttp.NewClient()
 		retryClient.HTTPClient.Timeout = c.maxRequestDuration
 		retryClient.HTTPClient.Jar = c.cookieJar
-		retryClient.HTTPClient.Transport = transport
 		retryClient.RetryMax = c.maxRetries
+		if !c.useDefaultTransport {
+			retryClient.HTTPClient.Transport = transport
+		}
 		httpClient = retryClient.StandardClient()
 	} else {
 		httpClient = &http.Client{}
 		httpClient.Timeout = c.maxRequestDuration
 		httpClient.Jar = c.cookieJar
-		httpClient.Transport = transport
+		if !c.useDefaultTransport {
+			httpClient.Transport = transport
+		}
 	}
 
 	if c.transportSkipVerification {

pkg/http/http_test.go

@@ -14,12 +14,51 @@ import (
 	"testing"
 	"time"
 
-	"github.com/SAP/jenkins-library/pkg/log"
+	"github.com/jarcoal/httpmock"
 	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+
+	"github.com/SAP/jenkins-library/pkg/log"
 )
 
+func TestDefaultTransport(t *testing.T) {
+	const testURL string = "https://localhost/api"
+
+	t.Run("with default transport", func(t *testing.T) {
+		httpmock.Activate()
+		defer httpmock.DeactivateAndReset()
+		httpmock.RegisterResponder(http.MethodGet, testURL, httpmock.NewStringResponder(200, `OK`))
+
+		client := Client{}
+		client.SetOptions(ClientOptions{UseDefaultTransport: true})
+		// test
+		response, err := client.SendRequest("GET", testURL, nil, nil, nil)
+		// assert
+		assert.NoError(t, err)
+		// assert.NotEmpty(t, count)
+		assert.Equal(t, 1, httpmock.GetTotalCallCount(), "unexpected number of requests")
+		content, err := ioutil.ReadAll(response.Body)
+		defer response.Body.Close()
+		require.NoError(t, err, "unexpected error while reading response body")
+		assert.Equal(t, "OK", string(content), "unexpected response content")
+	})
+	t.Run("with custom transport", func(t *testing.T) {
+		httpmock.Activate()
+		defer httpmock.DeactivateAndReset()
+		httpmock.RegisterResponder(http.MethodGet, testURL, httpmock.NewStringResponder(200, `OK`))
+
+		client := Client{}
+		// test
+		_, err := client.SendRequest("GET", testURL, nil, nil, nil)
+		// assert
+		assert.Error(t, err)
+		assert.Contains(t, err.Error(), "connect: connection refused")
+		assert.Equal(t, 0, httpmock.GetTotalCallCount(), "unexpected number of requests")
+	})
+}
+
 func TestSendRequest(t *testing.T) {
 	var passedHeaders = map[string][]string{}
 	passedCookies := []*http.Cookie{}