feat(engine): Added OptionFunc and With (#3572)

* feat: Added `OptionFunc` and `With`

* fix: `With(opts...)` must be after `New`

* feat: improve New with

* fix: test

* optimize code

* optimize nolint

* optimize code

Signed-off-by: Flc゛ <four_leaf_clover@foxmail.com>

---------

Signed-off-by: Flc゛ <four_leaf_clover@foxmail.com>

context_test.go

@@ -1000,7 +1000,7 @@ func TestContextRenderFile(t *testing.T) {
 	c.File("./gin.go")
 
 	assert.Equal(t, http.StatusOK, w.Code)
-	assert.Contains(t, w.Body.String(), "func New() *Engine {")
+	assert.Contains(t, w.Body.String(), "func New(opts ...OptionFunc) *Engine {")
 	// Content-Type='text/plain; charset=utf-8' when go version <= 1.16,
 	// else, Content-Type='text/x-go; charset=utf-8'
 	assert.NotEqual(t, "", w.Header().Get("Content-Type"))
@@ -1014,7 +1014,7 @@ func TestContextRenderFileFromFS(t *testing.T) {
 	c.FileFromFS("./gin.go", Dir(".", false))
 
 	assert.Equal(t, http.StatusOK, w.Code)
-	assert.Contains(t, w.Body.String(), "func New() *Engine {")
+	assert.Contains(t, w.Body.String(), "func New(opts ...OptionFunc) *Engine {")
 	// Content-Type='text/plain; charset=utf-8' when go version <= 1.16,
 	// else, Content-Type='text/x-go; charset=utf-8'
 	assert.NotEqual(t, "", w.Header().Get("Content-Type"))
@@ -1030,7 +1030,7 @@ func TestContextRenderAttachment(t *testing.T) {
 	c.FileAttachment("./gin.go", newFilename)
 
 	assert.Equal(t, 200, w.Code)
-	assert.Contains(t, w.Body.String(), "func New() *Engine {")
+	assert.Contains(t, w.Body.String(), "func New(opts ...OptionFunc) *Engine {")
 	assert.Equal(t, fmt.Sprintf("attachment; filename=\"%s\"", newFilename), w.Header().Get("Content-Disposition"))
 }
 
@@ -1057,7 +1057,7 @@ func TestContextRenderUTF8Attachment(t *testing.T) {
 	c.FileAttachment("./gin.go", newFilename)
 
 	assert.Equal(t, 200, w.Code)
-	assert.Contains(t, w.Body.String(), "func New() *Engine {")
+	assert.Contains(t, w.Body.String(), "func New(opts ...OptionFunc) *Engine {")
 	assert.Equal(t, `attachment; filename*=UTF-8''`+url.QueryEscape(newFilename), w.Header().Get("Content-Disposition"))
 }
 

gin.go

@@ -47,6 +47,9 @@ var regRemoveRepeatedChar = regexp.MustCompile("/{2,}")
 // HandlerFunc defines the handler used by gin middleware as return value.
 type HandlerFunc func(*Context)
 
+// OptionFunc defines the function to change the default configuration
+type OptionFunc func(*Engine)
+
 // HandlersChain defines a HandlerFunc slice.
 type HandlersChain []HandlerFunc
 
@@ -182,7 +185,7 @@ var _ IRouter = (*Engine)(nil)
 // - ForwardedByClientIP:    true
 // - UseRawPath:             false
 // - UnescapePathValues:     true
-func New() *Engine {
+func New(opts ...OptionFunc) *Engine {
 	debugPrintWARNINGNew()
 	engine := &Engine{
 		RouterGroup: RouterGroup{
@@ -211,15 +214,15 @@ func New() *Engine {
 	engine.pool.New = func() any {
 		return engine.allocateContext(engine.maxParams)
 	}
-	return engine
+	return engine.With(opts...)
 }
 
 // Default returns an Engine instance with the Logger and Recovery middleware already attached.
-func Default() *Engine {
+func Default(opts ...OptionFunc) *Engine {
 	debugPrintWARNINGDefault()
 	engine := New()
 	engine.Use(Logger(), Recovery())
-	return engine
+	return engine.With(opts...)
 }
 
 func (engine *Engine) Handler() http.Handler {
@@ -313,6 +316,15 @@ func (engine *Engine) Use(middleware ...HandlerFunc) IRoutes {
 	return engine
 }
 
+// With returns a new Engine instance with the provided options.
+func (engine *Engine) With(opts ...OptionFunc) *Engine {
+	for _, opt := range opts {
+		opt(engine)
+	}
+
+	return engine
+}
+
 func (engine *Engine) rebuild404Handlers() {
 	engine.allNoRoute = engine.combineHandlers(engine.noRoute)
 }

gin_test.go

@@ -696,3 +696,37 @@ func assertRoutePresent(t *testing.T, gotRoutes RoutesInfo, wantRoute RouteInfo)
 
 func handlerTest1(c *Context) {}
 func handlerTest2(c *Context) {}
+
+func TestNewOptionFunc(t *testing.T) {
+	var fc = func(e *Engine) {
+		e.GET("/test1", handlerTest1)
+		e.GET("/test2", handlerTest2)
+
+		e.Use(func(c *Context) {
+			c.Next()
+		})
+	}
+
+	r := New(fc)
+
+	routes := r.Routes()
+	assertRoutePresent(t, routes, RouteInfo{Path: "/test1", Method: "GET", Handler: "github.com/gin-gonic/gin.handlerTest1"})
+	assertRoutePresent(t, routes, RouteInfo{Path: "/test2", Method: "GET", Handler: "github.com/gin-gonic/gin.handlerTest2"})
+}
+
+func TestWithOptionFunc(t *testing.T) {
+	r := New()
+
+	r.With(func(e *Engine) {
+		e.GET("/test1", handlerTest1)
+		e.GET("/test2", handlerTest2)
+
+		e.Use(func(c *Context) {
+			c.Next()
+		})
+	})
+
+	routes := r.Routes()
+	assertRoutePresent(t, routes, RouteInfo{Path: "/test1", Method: "GET", Handler: "github.com/gin-gonic/gin.handlerTest1"})
+	assertRoutePresent(t, routes, RouteInfo{Path: "/test2", Method: "GET", Handler: "github.com/gin-gonic/gin.handlerTest2"})
+}