fix: github enterprise graphql endpoint url

Exposes Client.GraphQLURL to enable testing.

fixes drone#31

Author: hugoduncan

scm/client.go

@@ -89,7 +89,8 @@ type (
 		Client *http.Client
 
 		// Base URL for API requests.
-		BaseURL *url.URL
+		BaseURL    *url.URL
+		GraphQLURL *url.URL
 
 		// Services used for communicating with the API.
 		Driver        Driver

scm/driver/github/github.go

@@ -49,6 +49,13 @@ func New(uri string) (*scm.Client, error) {
 	client.Webhooks = &webhookService{client}
 
 	graphqlEndpoint := scm.UrlJoin(uri, "/graphql")
+	if strings.HasSuffix(uri, "/api/v3") {
+		graphqlEndpoint = scm.UrlJoin(uri[0:len(uri)-2], "graphql")
+	}
+	client.GraphQLURL, err = url.Parse(graphqlEndpoint)
+	if err != nil {
+		return nil, err
+	}
 	client.GraphQL = &dynamicGraphQLClient{client, graphqlEndpoint}
 
 	return client.Client, nil

scm/driver/github/github_test.go

@@ -34,6 +34,16 @@ func TestClient(t *testing.T) {
 	}
 }
 
+func TestGraphQLClient(t *testing.T) {
+	client, err := New("https://api.github.com")
+	if err != nil {
+		t.Error(err)
+	}
+	if got, want := client.GraphQLURL.String(), "https://api.github.com/graphql"; got != want {
+		t.Errorf("Want GraphQl Client URL %q, got %q", want, got)
+	}
+}
+
 func TestClient_Base(t *testing.T) {
 	client, err := New("https://github.example.com/api/v3")
 	if err != nil {
@@ -44,6 +54,16 @@ func TestClient_Base(t *testing.T) {
 	}
 }
 
+func TestEnterpriseGraphQLClient(t *testing.T) {
+	client, err := New("https://github.example.com/api/v3")
+	if err != nil {
+		t.Error(err)
+	}
+	if got, want := client.GraphQLURL.String(), "https://github.example.com/api/graphql"; got != want {
+		t.Errorf("Want GraphQl Client URL %q, got %q", want, got)
+	}
+}
+
 func TestClient_Default(t *testing.T) {
 	client := NewDefault()
 	if got, want := client.BaseURL.String(), "https://api.github.com/"; got != want {