feat: add automatic HEAD request generation from GET request

echo.go

@@ -92,6 +92,9 @@ type Echo struct {
 
 	// formParseMaxMemory is passed to Context for multipart form parsing (See http.Request.ParseMultipartForm)
 	formParseMaxMemory int64
+
+	// automatically registers a HEAD request within GET
+	autoHeadInGet bool
 }
 
 // JSONSerializer is the interface that encodes and decodes JSON to and from interfaces.
@@ -330,6 +333,7 @@ func New() *Echo {
 		Binder:             &DefaultBinder{},
 		JSONSerializer:     &DefaultJSONSerializer{},
 		formParseMaxMemory: defaultMemory,
+		autoHeadInGet:      true,
 	}
 
 	e.serveHTTPFunc = e.serveHTTP
@@ -341,6 +345,14 @@ func New() *Echo {
 	return e
 }
 
+// AutoHeadCancel turns the flag autoHeadInGet to false.
+//
+// This flag is used to register HEAD request automatically
+// everytime a GET request is registered.
+func (e *Echo) AutoHeadCancel() {
+	e.autoHeadInGet = false
+}
+
 // NewContext returns a new Context instance.
 //
 // Note: both request and response can be left to nil as Echo.ServeHTTP will call c.Reset(req,resp) anyway
@@ -437,7 +449,14 @@ func (e *Echo) DELETE(path string, h HandlerFunc, m ...MiddlewareFunc) RouteInfo
 
 // GET registers a new GET route for a path with matching handler in the router
 // with optional route-level middleware. Panics on error.
+//
+// Note: if autoHeadInGet flag is true, it will also register a HEAD request
+// to the same path.
 func (e *Echo) GET(path string, h HandlerFunc, m ...MiddlewareFunc) RouteInfo {
+	if e.autoHeadInGet {
+		_ = e.HEAD(path, h, m...)
+	}
+
 	return e.Add(http.MethodGet, path, h, m...)
 }
 
@@ -639,7 +658,7 @@ func (e *Echo) Add(method, path string, handler HandlerFunc, middleware ...Middl
 
 // Group creates a new router group with prefix and optional group-level middleware.
 func (e *Echo) Group(prefix string, m ...MiddlewareFunc) (g *Group) {
-	g = &Group{prefix: prefix, echo: e}
+	g = &Group{prefix: prefix, echo: e, autoHeadInGet: true}
 	g.Use(m...)
 	return
 }

echo_test.go

@@ -529,6 +529,16 @@ func TestEchoWrapMiddleware(t *testing.T) {
 	assert.Equal(t, "/:id", actualPattern)
 }
 
+func TestAutoHeadCancel(t *testing.T) {
+	e := New()
+
+	assert.Equal(t, true, e.autoHeadInGet)
+
+	e.AutoHeadCancel()
+
+	assert.Equal(t, false, e.autoHeadInGet)
+}
+
 func TestEchoConnect(t *testing.T) {
 	e := New()
 
@@ -580,6 +590,24 @@ func TestEchoGet(t *testing.T) {
 	assert.Equal(t, "OK", body)
 }
 
+func TestEchoAutoHead(t *testing.T) {
+	e := New()
+
+	assert.Equal(t, true, e.autoHeadInGet) // guarantees the flag is true
+	ri := e.GET("/", func(c *Context) error {
+		return c.String(http.StatusTeapot, "OK")
+	})
+
+	assert.Equal(t, http.MethodGet, ri.Method)
+	assert.Equal(t, "/", ri.Path)
+	assert.Equal(t, http.MethodGet+":/", ri.Name)
+	assert.Nil(t, ri.Parameters)
+
+	status, body := request(http.MethodHead, "/", e)
+	assert.Equal(t, http.StatusTeapot, status)
+	assert.Equal(t, "OK", body)
+}
+
 func TestEchoHead(t *testing.T) {
 	e := New()
 
@@ -909,7 +937,7 @@ func TestEchoMethodNotAllowed(t *testing.T) {
 	e.ServeHTTP(rec, req)
 
 	assert.Equal(t, http.StatusMethodNotAllowed, rec.Code)
-	assert.Equal(t, "OPTIONS, GET", rec.Header().Get(HeaderAllow))
+	assert.Equal(t, "OPTIONS, GET, HEAD", rec.Header().Get(HeaderAllow))
 }
 
 func TestEcho_OnAddRoute(t *testing.T) {
@@ -950,6 +978,7 @@ func TestEcho_OnAddRoute(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 
 			e := New()
+			e.AutoHeadCancel()
 
 			added := make([]string, 0)
 			cnt := 0

group.go

@@ -12,9 +12,15 @@ import (
 // routes that share a common middleware or functionality that should be separate
 // from the parent echo instance while still inheriting from it.
 type Group struct {
-	echo       *Echo
-	prefix     string
-	middleware []MiddlewareFunc
+	echo          *Echo
+	prefix        string
+	middleware    []MiddlewareFunc
+	autoHeadInGet bool
+}
+
+// AutoHeadCancel implements `Echo#AutoHeadCancel()` for the Group struct.
+func (g *Group) AutoHeadCancel() {
+	g.autoHeadInGet = false
 }
 
 // Use implements `Echo#Use()` for sub-routes within the Group.
@@ -35,6 +41,10 @@ func (g *Group) DELETE(path string, h HandlerFunc, m ...MiddlewareFunc) RouteInf
 
 // GET implements `Echo#GET()` for sub-routes within the Group. Panics on error.
 func (g *Group) GET(path string, h HandlerFunc, m ...MiddlewareFunc) RouteInfo {
+	if g.autoHeadInGet {
+		_ = g.HEAD(path, h, m...)
+	}
+
 	return g.Add(http.MethodGet, path, h, m...)
 }
 
@@ -105,6 +115,7 @@ func (g *Group) Group(prefix string, middleware ...MiddlewareFunc) (sg *Group) {
 	m = append(m, g.middleware...)
 	m = append(m, middleware...)
 	sg = g.echo.Group(g.prefix+prefix, m...)
+	sg.autoHeadInGet = true
 	return
 }
 

group_test.go

@@ -162,6 +162,17 @@ func TestGroupRouteMiddlewareWithMatchAny(t *testing.T) {
 
 }
 
+func TestAutoHeadCancelInGroup(t *testing.T) {
+	e := New()
+	g := e.Group("/group")
+
+	assert.Equal(t, true, g.autoHeadInGet)
+
+	g.AutoHeadCancel()
+
+	assert.Equal(t, false, g.autoHeadInGet)
+}
+
 func TestGroup_CONNECT(t *testing.T) {
 	e := New()
 
@@ -198,6 +209,25 @@ func TestGroup_DELETE(t *testing.T) {
 	assert.Equal(t, `OK`, body)
 }
 
+func TestGroup_AutoHEAD_in_GET(t *testing.T) {
+	e := New()
+
+	users := e.Group("/users")
+	ri := users.GET("/activate", func(c *Context) error {
+		return c.String(http.StatusTeapot, "OK")
+	})
+
+	assert.Equal(t, true, users.autoHeadInGet)
+	assert.Equal(t, http.MethodGet, ri.Method)
+	assert.Equal(t, "/users/activate", ri.Path)
+	assert.Equal(t, http.MethodGet+":/users/activate", ri.Name)
+	assert.Nil(t, ri.Parameters)
+
+	status, body := request(http.MethodHead, "/users/activate", e)
+	assert.Equal(t, http.StatusTeapot, status)
+	assert.Equal(t, "OK", body)
+}
+
 func TestGroup_HEAD(t *testing.T) {
 	e := New()