go-github: add support for getting content of a repository's license

Fixes #228
Fixes #301

Change-Id: I43d414332baa87b430487ea03d125633f8e40bd5

github/repos.go

@@ -538,3 +538,22 @@ func (s *RepositoriesService) EditBranch(owner, repo, branchName string, branch
 
 	return b, resp, err
 }
+
+// License gets the contents of a repository's license if one is detected.
+//
+// GitHub API docs: https://developer.github.com/v3/licenses/#get-the-contents-of-a-repositorys-license
+func (s *RepositoriesService) License(owner, repo string) (*License, *Response, error) {
+	u := fmt.Sprintf("repos/%v/%v/license", owner, repo)
+	req, err := s.client.NewRequest("GET", u, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	r := &Repository{}
+	resp, err := s.client.Do(req, r)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return r.License, resp, err
+}

github/repos_test.go

@@ -456,3 +456,28 @@ func TestRepositoriesService_ListLanguages_invalidOwner(t *testing.T) {
 	_, _, err := client.Repositories.ListLanguages("%", "%")
 	testURLParseError(t, err)
 }
+
+func TestRepositoriesService_License(t *testing.T) {
+	setup()
+	defer teardown()
+
+	mux.HandleFunc("/repos/o/r/license", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"license":{"key":"mit","name":"MIT License","url":"https://api.github.com/licenses/mit","featured":true}}`)
+	})
+
+	got, _, err := client.Repositories.License("o", "r")
+	if err != nil {
+		t.Errorf("Repositories.License returned error: %v", err)
+	}
+
+	want := &License{
+		Name:     String("MIT License"),
+		Key:      String("mit"),
+		URL:      String("https://api.github.com/licenses/mit"),
+		Featured: Bool(true),
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("Repositories.License returned %+v, want %+v", got, want)
+	}
+}