Fix internal handlers ServiceBuilder composition

pkg/server/service/service_test.go

@@ -18,9 +18,9 @@ import (
 	"github.com/traefik/traefik/v2/pkg/testhelpers"
 )
 
-type MockForwarder struct{}
+type mockForwarder struct{}
 
-func (MockForwarder) ServeHTTP(http.ResponseWriter, *http.Request) {
+func (mockForwarder) ServeHTTP(http.ResponseWriter, *http.Request) {
 	panic("implement me")
 }
 
@@ -44,14 +44,14 @@ func TestGetLoadBalancer(t *testing.T) {
 					},
 				},
 			},
-			fwd:         &MockForwarder{},
+			fwd:         &mockForwarder{},
 			expectError: true,
 		},
 		{
 			desc:        "Succeeds when there are no servers",
 			serviceName: "test",
 			service:     &dynamic.ServersLoadBalancer{},
-			fwd:         &MockForwarder{},
+			fwd:         &mockForwarder{},
 			expectError: false,
 		},
 		{
@@ -60,7 +60,7 @@ func TestGetLoadBalancer(t *testing.T) {
 			service: &dynamic.ServersLoadBalancer{
 				Sticky: &dynamic.Sticky{Cookie: &dynamic.Cookie{}},
 			},
-			fwd:         &MockForwarder{},
+			fwd:         &mockForwarder{},
 			expectError: false,
 		},
 	}
@@ -476,6 +476,48 @@ func Test1xxResponses(t *testing.T) {
 	}
 }
 
+type serviceBuilderFunc func(ctx context.Context, serviceName string) (http.Handler, error)
+
+func (s serviceBuilderFunc) BuildHTTP(ctx context.Context, serviceName string) (http.Handler, error) {
+	return s(ctx, serviceName)
+}
+
+type internalHandler struct{}
+
+func (internalHandler) ServeHTTP(_ http.ResponseWriter, _ *http.Request) {}
+
+func TestManager_ServiceBuilders(t *testing.T) {
+	var internalHandler internalHandler
+
+	manager := NewManager(map[string]*runtime.ServiceInfo{
+		"test@test": {
+			Service: &dynamic.Service{
+				LoadBalancer: &dynamic.ServersLoadBalancer{},
+			},
+		},
+	}, nil, nil, &RoundTripperManager{
+		roundTrippers: map[string]http.RoundTripper{
+			"default@internal": http.DefaultTransport,
+		},
+	}, serviceBuilderFunc(func(rootCtx context.Context, serviceName string) (http.Handler, error) {
+		if strings.HasSuffix(serviceName, "@internal") {
+			return internalHandler, nil
+		}
+		return nil, nil
+	}))
+
+	h, err := manager.BuildHTTP(context.Background(), "test@internal")
+	require.NoError(t, err)
+	assert.Equal(t, internalHandler, h)
+
+	h, err = manager.BuildHTTP(context.Background(), "test@test")
+	require.NoError(t, err)
+	assert.NotNil(t, h)
+
+	_, err = manager.BuildHTTP(context.Background(), "wrong@test")
+	assert.Error(t, err)
+}
+
 func TestManager_Build(t *testing.T) {
 	testCases := []struct {
 		desc         string