feat(sfn): make sfn init function optional (#630)

cli/serverless/golang/serverless.go

@@ -1,6 +1,7 @@
 package golang
 
 import (
+	"bufio"
 	"bytes"
 	"errors"
 	"fmt"
@@ -49,18 +50,21 @@ func (s *GolangServerless) Init(opts *serverless.Options) error {
 
 	// append main function
 	ctx := Context{
-		Name:       s.opts.Name,
-		ZipperAddr: s.opts.ZipperAddr,
-		Credential: s.opts.Credential,
-		UseEnv:     s.opts.UseEnv,
+		Name:         s.opts.Name,
+		ZipperAddr:   s.opts.ZipperAddr,
+		Credential:   s.opts.Credential,
+		UseEnv:       s.opts.UseEnv,
+		WithInitFunc: containsInitWithoutComment(source),
 	}
 
 	// determine: rx stream serverless or raw bytes serverless.
 	isRx := strings.Contains(string(source), "rx.Stream")
 	isWasm := true
 	mainFuncTmpl := ""
-	mainFunc := WasmMainFuncTmpl
-	var err error
+	mainFunc, err := RenderTmpl(string(WasmMainFuncTmpl), &ctx)
+	if err != nil {
+		return fmt.Errorf("Init: %s", err)
+	}
 	if isRx {
 		if isWasm {
 			return errors.New("wasm does not support rx.Stream")
@@ -251,6 +255,18 @@ func generateCode(fset *token.FileSet, file *ast.File) ([]byte, error) {
 	return buffer.Bytes(), nil
 }
 
+func containsInitWithoutComment(source []byte) bool {
+	scanner := bufio.NewScanner(bytes.NewReader(source))
+	for scanner.Scan() {
+		line := strings.TrimLeft(scanner.Text(), " ")
+
+		if strings.Contains(line, "Init()") && !strings.HasPrefix(line, "//") {
+			return true
+		}
+	}
+	return false
+}
+
 func init() {
 	serverless.Register(&GolangServerless{}, ".go")
 }

cli/serverless/golang/serverless_test.go

@@ -0,0 +1,43 @@
+package golang
+
+import "testing"
+
+func TestContainsInitWithoutComment(t *testing.T) {
+	type args struct {
+		source []byte
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			name: "init function with comment",
+			args: args{
+				source: []byte(`// func Init() error {`),
+			},
+			want: false,
+		},
+		{
+			name: "init function without comment",
+			args: args{
+				source: []byte(`func Init() error {`),
+			},
+			want: true,
+		},
+		{
+			name: "no init function",
+			args: args{
+				source: []byte(``),
+			},
+			want: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := containsInitWithoutComment(tt.args.source); got != tt.want {
+				t.Errorf("containInitFunc() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

cli/serverless/golang/template.go

@@ -40,6 +40,8 @@ type Context struct {
 	Credential string
 	// use environment variables
 	UseEnv bool
+	// WithInitFunc determines whether to work with init function
+	WithInitFunc bool
 }
 
 // RenderTmpl renders the template with the given context

cli/serverless/golang/templates/wasm_main.tmpl

@@ -2,5 +2,7 @@
 func main() {
 	guest.DataTags = DataTags
 	guest.Handler = Handler
+	{{if .WithInitFunc}}
 	guest.Init = Init
+	{{end}}
 }