feat(cli): yomo init with test file (#680)

# Description

`yomo init` command now generates `app_test.go` template for testing
`app.go`.

cli/cli.go

@@ -18,8 +18,9 @@ import (
 
 // defaultSFNFile is the default serverless file name
 const (
-	defaultSFNSourceFile   = "app.go"
-	defaultSFNCompliedFile = "sfn.wasm"
+	defaultSFNSourceFile     = "app.go"
+	defaultSFNTestSourceFile = "app_test.go"
+	defaultSFNCompliedFile   = "sfn.wasm"
 )
 
 // GetRootPath get root path

cli/init.go

@@ -60,6 +60,13 @@ var initCmd = &cobra.Command{
 			return
 		}
 
+		// create app_test.go
+		testName := filepath.Join(name, defaultSFNTestSourceFile)
+		if err := file.PutContents(testName, golang.InitTestTmpl); err != nil {
+			log.FailureStatusEvent(os.Stdout, "Write unittest tmpl into app_test.go file failure with the error: %v", err)
+			return
+		}
+
 		// create .env
 		fname = filepath.Join(name, ".env")
 		if err := file.PutContents(fname, []byte(fmt.Sprintf("YOMO_SFN_NAME=%s\n", name))); err != nil {

cli/serverless/golang/template.go

@@ -24,6 +24,9 @@ var PartialsTmpl []byte
 //go:embed templates/init.tmpl
 var InitTmpl []byte
 
+//go:embed templates/init_test.tmpl
+var InitTestTmpl []byte
+
 //go:embed templates/init_rx.tmpl
 var InitRxTmpl []byte
 

cli/serverless/golang/templates/init_test.tmpl

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/yomorun/yomo/serverless/mock"
+)
+
+func TestHandler(t *testing.T) {
+	tests := []struct {
+		name string
+		ctx  *mock.MockContext
+		// want is the expected data and tag that be written by ctx.Write
+		want []mock.DataAndTag
+	}{
+		{
+			name: "upper",
+			ctx:  mock.NewMockContext([]byte("hello"), 0x33),
+			want: []mock.DataAndTag{
+				{Data: []byte("HELLO"), Tag: 0x34},
+			},
+		},
+		// TODO: add more test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			Handler(tt.ctx)
+			got := tt.ctx.RecordWritten()
+
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("TestHandler got: %v, want: %v", got, tt.want)
+			}
+		})
+	}
+}

serverless/mock/mock_context.go

@@ -0,0 +1,62 @@
+package mock
+
+import (
+	"sync"
+
+	"github.com/yomorun/yomo/serverless"
+	"github.com/yomorun/yomo/serverless/guest"
+)
+
+// DataAndTag is a pair of data and tag.
+type DataAndTag struct {
+	Data []byte
+	Tag  uint32
+}
+
+// MockContext mock context.
+type MockContext struct {
+	data []byte
+	tag  uint32
+
+	mu      sync.Mutex
+	wrSlice []DataAndTag
+}
+
+// NewMockContext returns the mock context.
+// the data is that returned by ctx.Data(), the tag is that returned by ctx.Tag().
+func NewMockContext(data []byte, tag uint32) *MockContext {
+	return &MockContext{
+		data: data,
+		tag:  tag,
+	}
+}
+
+func (c *MockContext) Data() []byte {
+	return c.data
+}
+func (c *MockContext) Tag() uint32 {
+	return c.tag
+}
+func (m *MockContext) HTTP() serverless.HTTP {
+	return &guest.GuestHTTP{}
+}
+
+func (c *MockContext) Write(tag uint32, data []byte) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.wrSlice = append(c.wrSlice, DataAndTag{
+		Data: data,
+		Tag:  tag,
+	})
+
+	return nil
+}
+
+// RecordWritten returns the data records be written with `ctx.Write`.
+func (c *MockContext) RecordWritten() []DataAndTag {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.wrSlice
+}