Merge pull request juju#80 from mhilton/000-httptesting-transport

Add Transport to httptesting

Add a request rewriting RoundTripper to httptesting.

(Review request: http://reviews.vapour.ws/r/2825/)

Author: jujubot

httptesting/http.go

@@ -321,3 +321,40 @@ type readSeekNopCloser struct {
 func (readSeekNopCloser) Close() error {
 	return nil
 }
+
+// URLRewritingTransport is an http.RoundTripper that can rewrite request
+// URLs. If the request URL has the prefix specified in Match that part
+// will be changed to the value specified in Replace. RoundTripper will
+// then be used to perform the resulting request. If RoundTripper is nil
+// http.DefaultTransport will be used.
+//
+// This can be used in tests that, for whatever reason, need to make a
+// call to a URL that's not in our control but we want to control the
+// results of HTTP requests to that URL.
+type URLRewritingTransport struct {
+	MatchPrefix  string
+	Replace      string
+	RoundTripper http.RoundTripper
+}
+
+// RoundTrip implements http.RoundTripper.
+func (t URLRewritingTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	rt := t.RoundTripper
+	if rt == nil {
+		rt = http.DefaultTransport
+	}
+	if !strings.HasPrefix(req.URL.String(), t.MatchPrefix) {
+		return rt.RoundTrip(req)
+	}
+	req1 := *req
+	var err error
+	req1.URL, err = url.Parse(t.Replace + strings.TrimPrefix(req.URL.String(), t.MatchPrefix))
+	if err != nil {
+		panic(err)
+	}
+	resp, err := rt.RoundTrip(&req1)
+	if resp != nil {
+		resp.Request = req
+	}
+	return resp, err
+}

httptesting/http_test.go

@@ -319,3 +319,41 @@ func (*requestsSuite) TestDoRequestWithInferrableContentLength(c *gc.C) {
 // calls. Failures are already massively tested in practice. DoRequest and
 // AssertJSONResponse are also indirectly tested as they are called by
 // AssertJSONCall.
+
+type urlRewritingTransportSuite struct {
+	server *httptest.Server
+}
+
+var _ = gc.Suite(&urlRewritingTransportSuite{})
+
+func (s *urlRewritingTransportSuite) SetUpTest(c *gc.C) {
+	s.server = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(r.URL.String()))
+	}))
+}
+
+func (s *urlRewritingTransportSuite) TestTransport(c *gc.C) {
+	t := httptesting.URLRewritingTransport{
+		MatchPrefix: "http://example.com",
+		Replace:     s.server.URL,
+	}
+	client := http.Client{
+		Transport: &t,
+	}
+	resp, err := client.Get("http://example.com/path")
+	c.Assert(err, jc.ErrorIsNil)
+	body, err := ioutil.ReadAll(resp.Body)
+	c.Assert(err, jc.ErrorIsNil)
+	resp.Body.Close()
+	c.Assert(resp.Request.URL.String(), gc.Equals, "http://example.com/path")
+	c.Assert(string(body), gc.Equals, "/path")
+
+	t.RoundTripper = &http.Transport{}
+	resp, err = client.Get(s.server.URL + "/otherpath")
+	c.Assert(err, jc.ErrorIsNil)
+	body, err = ioutil.ReadAll(resp.Body)
+	c.Assert(err, jc.ErrorIsNil)
+	resp.Body.Close()
+	c.Assert(resp.Request.URL.String(), gc.Equals, s.server.URL+"/otherpath")
+	c.Assert(string(body), gc.Equals, "/otherpath")
+}