feat: support Req()

README.md

@@ -86,3 +86,12 @@ json, err = request.
   Proxy("http://myproxy.com:8080").
   JSON()
 ```
+
+### Convert to http.Request instance
+
+```go
+req, err = request.
+  Post("http://mysite.com/form").
+  Auth("name", "passwd").
+  Req()
+```

request.go

@@ -19,7 +19,7 @@ import (
 )
 
 // Version is this package's version number.
-const Version = "1.5.3"
+const Version = "1.6.0"
 
 // Errors used by this package.
 var (
@@ -417,6 +417,29 @@ func (c *Client) End() (*Response, error) {
 	return c.res, nil
 }
 
+// Req returns the representing http.Request instance of this request.
+// It is often used in wirting tests.
+func (c *Client) Req() (*http.Request, error) {
+	if c.url == nil {
+		return nil, ErrLackURL
+	}
+
+	if c.method == "" {
+		return nil, ErrLackMethod
+	}
+
+	if c.err != nil {
+		return nil, c.err
+	}
+
+	if err := c.assemble(); err != nil {
+		c.err = err
+		return nil, err
+	}
+
+	return c.req, nil
+}
+
 // JSON sends the HTTP request and returns the reponse body with JSON format.
 func (c *Client) JSON(v ...interface{}) (interface{}, error) {
 	if _, err := c.End(); err != nil {

request_test.go

@@ -3,14 +3,12 @@ package request
 import (
 	"fmt"
 	"net/http"
+	"net/http/cookiejar"
+	"net/http/httptest"
 	"net/url"
 	"testing"
 	"time"
 
-	"net/http/httptest"
-
-	"net/http/cookiejar"
-
 	"github.com/go-http-utils/headers"
 	"github.com/stretchr/testify/suite"
 )
@@ -498,6 +496,15 @@ func (s *RequestSuite) TestProxyInvalidSocks5URL() {
 	s.NotNil(err)
 }
 
+func (s *RequestSuite) TestReq() {
+	req, err := s.c.Post(testHost + "/post").
+		Accept("json").
+		Req()
+
+	s.Nil(err)
+	s.Equal(req.Header.Get(headers.Accept), "application/json")
+}
+
 func TestRequest(t *testing.T) {
 	suite.Run(t, new(RequestSuite))
 }