Add Clue Mock Generator tool under mock (#192)

* Add Clue Mock Generator under mock

* Handle omitted types correctly in function parameters and results

* Omit repeated types until the last in generated function parameters and results

* Add tests to mock/cmd/cmg/pkg/parse

* Add tests to mock/cmd/cmg/pkg/generate and implement more types

* Add support for generic interfaces

* Support type constraints on named types and finish up some tests

* Omit repeated types in struct literals

* Add Clue Mock Gen usage to example weather system

* Update weather example README with Clue Mock Gen changes

CONTRIBUTING.md

@@ -12,7 +12,7 @@ Below are some guidelines to follow when contributing to this project:
   and follow the checklist presented in the issue description section. A simple
   code snippet that reproduces your issue helps immensely.
 * If you know how to fix your bug, we highly encourage PR contributions. See
-  [How Can I Get Started section](#how-can-i-get-started?) on how to submit a PR.
+  [How Can I Get Started section](#how-can-i-get-started) on how to submit a PR.
 * For feature requests and submitting major changes, [open an issue](https://github.com/goadesign/clue/issues/new)
   or hop on to our slack channel (see <https://goa.design> to join) to discuss
   the feature first.

example/weather/README.md

@@ -206,7 +206,7 @@ check := health.Handler(health.NewChecker(
 
 The health check and metric handlers are mounted on a separate HTTP handler (the
 global `http` standard library handler) to avoid logging, tracing and otherwise
-instrumenting the correspinding requests.
+instrumenting the corresponding requests.
 
 ```go
 http.Handle("/livez", check)
@@ -246,14 +246,17 @@ func New(cc *grpc.ClientConn) Client {
 }
 ```
 
-The mock is instantiated via the `NewMock` function located in the `mock.go` file:
+The mock is instantiated via the `NewClient` function located in the
+`mocks/client.go` file that is generated using the `cmg` tool:
 
 ```go
-var _ Client = &Mock{}
-
 // NewMock returns a new mock client.
-func NewMock(t *testing.T) *Mock {
-        return &Mock{mock.New(), t}
+func NewClient(t *testing.T) *Client {
+        var (
+                m                     = &Client{mock.New(), t}
+                _ = forecaster.Client = m
+        )
+        return m
 }
 ```
 
@@ -262,43 +265,46 @@ create call sequences and validate them:
 
 ```go
 type (
-               // Mock implementation of the forecast client.
-        Mock struct {
+        // Mock implementation of the forecast client.
+        Client struct {
                 m *mock.Mock
                 t *testing.T
         }
+
+        ClientGetForecastFunc func(ctx context.Context, lat, long float64) (*forecaster.Forecast, error)
 )
 ```
 
 ```go
 // AddGetForecastFunc adds f to the mocked call sequence.
-func (m *Mock) AddGetForecastFunc(f GetForecastFunc) {
+func (m *Client) AddGetForecast(f ClientGetForecastFunc) {
         m.m.Add("GetForecast", f)
 }
 
 // SetGetForecastFunc sets f for all calls to the mocked method.
-func (m *Mock) SetGetForecastFunc(f GetForecastFunc) {
+func (m *Client) SetGetForecast(f ClientGetForecastFunc) {
         m.m.Set("GetForecast", f)
 }
 
 // GetForecast implements the Client interface.
-func (m *Mock) GetForecast(ctx context.Context, lat, long float64) (*Forecast, error) {
+func (m *Client) GetForecast(ctx context.Context, lat, long float64) (*forecaster.Forecast, error) {
         if f := m.m.Next("GetForecast"); f != nil {
-                return f.(GetForecastFunc)(ctx, lat, long)
+                return f.(ClientGetForecastFunc)(ctx, lat, long)
         }
-        m.t.Error("unexpected call to GetForecast")
+        m.t.Helper()
+        m.t.Error("unexpected GetForecast call")
         return nil, nil
 }
 ```
 
-Tests leverage the `AddGetForecastFunc` and `SetGetForecastFunc` methods to
-configure the mock client:
+Tests leverage the `AddGetForecast` and `SetGetForecast` methods to configure
+the mock client:
 
 ```go
-lmock := locator.NewMock(t)
-lmock.AddGetLocationFunc(c.locationFunc) // Mock the locator service.
-fmock := forecaster.NewMock(t)
-fmock.AddGetForecastFunc(c.forecastFunc) // Mock the forecast service.
+lmock := mocklocator.NewClient(t)
+lmock.AddGetLocation(c.locationFunc) // Mock the locator service.
+fmock := mockforecaster.NewClient(t)
+fmock.AddGetForecast(c.forecastFunc) // Mock the forecast service.
 s := New(fmock, lmock) // Create front service instance for testing
 ```
 

example/weather/scripts/gen

@@ -9,6 +9,7 @@ echo "Generating Goa code..."
 
 for svc in front forecaster locator; do
   goa gen goa.design/clue/example/weather/services/${svc}/design -o services/${svc}
+  cmg gen ./services/${svc}/clients/*/
 done
 
 popd

example/weather/scripts/setup

@@ -21,6 +21,7 @@ fi
 
 go mod download
 go install honnef.co/go/tools/cmd/staticcheck@latest
+go install goa.design/clue/mock/cmd/cmg@latest
 go install goa.design/model/cmd/mdl@latest
 go install goa.design/goa/v3/...@v3
 go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.27.1

example/weather/services/forecaster/forecast_test.go

@@ -6,14 +6,15 @@ import (
 	"testing"
 
 	"goa.design/clue/example/weather/services/forecaster/clients/weathergov"
+	mockweathergov "goa.design/clue/example/weather/services/forecaster/clients/weathergov/mocks"
 	genforecaster "goa.design/clue/example/weather/services/forecaster/gen/forecaster"
 )
 
 func TestForecast(t *testing.T) {
 	// Create mock call sequence with first successful call returning a
 	// forecast then failing.
-	wc := weathergov.NewMock(t)
-	wc.AddGetForecastFunc(func(ctx context.Context, lat, long float64) (*weathergov.Forecast, error) {
+	wc := mockweathergov.NewClient(t)
+	wc.AddGetForecast(func(ctx context.Context, lat, long float64) (*weathergov.Forecast, error) {
 		// Make sure service passes the right values to the client
 		if lat != latitude {
 			t.Errorf("got latitude %f, expected %f", lat, latitude)
@@ -23,7 +24,7 @@ func TestForecast(t *testing.T) {
 		}
 		return mockForecast, nil
 	})
-	wc.AddGetForecastFunc(func(_ context.Context, _, _ float64) (*weathergov.Forecast, error) {
+	wc.AddGetForecast(func(_ context.Context, _, _ float64) (*weathergov.Forecast, error) {
 		return nil, fmt.Errorf("test failure")
 	})
 

example/weather/services/forecaster/gen/grpc/forecaster/pb/goadesign_goagen_forecaster.proto

@@ -1,4 +1,4 @@
-// Code generated with goa v3.10.2, DO NOT EDIT.
+// Code generated with goa v3.11.0, DO NOT EDIT.
 //
 // Forecaster protocol buffer definition
 //