chore(http): allow to send prepared requests (#2580)

* Update http.go

* fix c&p issue

* convert URL to string

* Apply suggestions from code review

fix code climate findings

* add test case

pkg/http/http.go

@@ -129,8 +129,6 @@ func (c *Client) Upload(data UploadRequestData) (*http.Response, error) {
 		return nil, errors.New(fmt.Sprintf("Http method %v is not allowed. Possible values are %v or %v", data.Method, http.MethodPost, http.MethodPut))
 	}
 
-	httpClient := c.initialize()
-
 	bodyBuffer := &bytes.Buffer{}
 	bodyWriter := multipart.NewWriter(bodyBuffer)
 
@@ -166,12 +164,7 @@ func (c *Client) Upload(data UploadRequestData) (*http.Response, error) {
 	request.Header.Add("Content-Type", "multipart/form-data; boundary=\""+boundary+"\"")
 	request.Header.Add("Connection", "Keep-Alive")
 
-	response, err := httpClient.Do(request)
-	if err != nil {
-		return response, errors.Wrapf(err, "HTTP %v request to %v failed with error", data.Method, data.URL)
-	}
-
-	return c.handleResponse(response, data.URL)
+	return c.Send(request)
 }
 
 // SendRequest sends an http request with a defined method
@@ -179,19 +172,22 @@ func (c *Client) Upload(data UploadRequestData) (*http.Response, error) {
 // On error, any Response can be ignored and the Response.Body
 // does not need to be closed.
 func (c *Client) SendRequest(method, url string, body io.Reader, header http.Header, cookies []*http.Cookie) (*http.Response, error) {
-	httpClient := c.initialize()
-
 	request, err := c.createRequest(method, url, body, &header, cookies)
 	if err != nil {
 		return &http.Response{}, errors.Wrapf(err, "error creating %v request to %v", method, url)
 	}
 
+	return c.Send(request)
+}
+
+// Send sends an http request
+func (c *Client) Send(request *http.Request) (*http.Response, error) {
+	httpClient := c.initialize()
 	response, err := httpClient.Do(request)
 	if err != nil {
-		return response, errors.Wrapf(err, "error calling %v", url)
+		return response, errors.Wrapf(err, "HTTP %v request to %v failed", request.Method, request.URL)
 	}
-
-	return c.handleResponse(response, url)
+	return c.handleResponse(response, request.URL.String())
 }
 
 // SetOptions sets options used for the http client

pkg/http/http_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/base64"
 	"encoding/xml"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -23,6 +24,40 @@ import (
 	"github.com/SAP/jenkins-library/pkg/log"
 )
 
+func TestSend(t *testing.T) {
+	testURL := "https://example.org"
+
+	request, err := http.NewRequest(http.MethodGet, testURL, nil)
+	require.NoError(t, err)
+
+	t.Run("success", func(t *testing.T) {
+		// given
+		httpmock.Activate()
+		defer httpmock.DeactivateAndReset()
+		httpmock.RegisterResponder(http.MethodGet, testURL, httpmock.NewStringResponder(200, `OK`))
+		client := Client{}
+		client.SetOptions(ClientOptions{UseDefaultTransport: true})
+		// when
+		response, err := client.Send(request)
+		// then
+		assert.NoError(t, err)
+		assert.NotNil(t, response)
+	})
+	t.Run("failure", func(t *testing.T) {
+		// given
+		httpmock.Activate()
+		defer httpmock.DeactivateAndReset()
+		httpmock.RegisterResponder(http.MethodGet, testURL, httpmock.NewErrorResponder(errors.New("failure")))
+		client := Client{}
+		client.SetOptions(ClientOptions{UseDefaultTransport: true})
+		// when
+		response, err := client.Send(request)
+		// then
+		assert.Error(t, err)
+		assert.Nil(t, response)
+	})
+}
+
 func TestDefaultTransport(t *testing.T) {
 	const testURL string = "https://localhost/api"