Added support for SameSite cookie flag (gin-gonic#1615)

* Added support for SameSite cookie flag

* fixed tests.

* Update context.go

* Update context_test.go

* Update context_test.go

Co-authored-by: thinkerou <thinkerou@gmail.com>
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>

context.go

@@ -775,7 +775,7 @@ func (c *Context) GetRawData() ([]byte, error) {
 // SetCookie adds a Set-Cookie header to the ResponseWriter's headers.
 // The provided cookie must have a valid Name. Invalid cookies may be
 // silently dropped.
-func (c *Context) SetCookie(name, value string, maxAge int, path, domain string, secure, httpOnly bool) {
+func (c *Context) SetCookie(name, value string, maxAge int, path, domain string, sameSite http.SameSite, secure, httpOnly bool) {
 	if path == "" {
 		path = "/"
 	}
@@ -785,6 +785,7 @@ func (c *Context) SetCookie(name, value string, maxAge int, path, domain string,
 		MaxAge:   maxAge,
 		Path:     path,
 		Domain:   domain,
+		SameSite: sameSite,
 		Secure:   secure,
 		HttpOnly: httpOnly,
 	})

context_test.go

@@ -602,14 +602,14 @@ func TestContextPostFormMultipart(t *testing.T) {
 
 func TestContextSetCookie(t *testing.T) {
 	c, _ := CreateTestContext(httptest.NewRecorder())
-	c.SetCookie("user", "gin", 1, "/", "localhost", true, true)
-	assert.Equal(t, "user=gin; Path=/; Domain=localhost; Max-Age=1; HttpOnly; Secure", c.Writer.Header().Get("Set-Cookie"))
+	c.SetCookie("user", "gin", 1, "/", "localhost", http.SameSiteLaxMode, true, true)
+	assert.Equal(t, "user=gin; Path=/; Domain=localhost; Max-Age=1; HttpOnly; Secure; SameSite=Lax", c.Writer.Header().Get("Set-Cookie"))
 }
 
 func TestContextSetCookiePathEmpty(t *testing.T) {
 	c, _ := CreateTestContext(httptest.NewRecorder())
-	c.SetCookie("user", "gin", 1, "", "localhost", true, true)
-	assert.Equal(t, "user=gin; Path=/; Domain=localhost; Max-Age=1; HttpOnly; Secure", c.Writer.Header().Get("Set-Cookie"))
+	c.SetCookie("user", "gin", 1, "", "localhost", http.SameSiteLaxMode, true, true)
+	assert.Equal(t, "user=gin; Path=/; Domain=localhost; Max-Age=1; HttpOnly; Secure; SameSite=Lax", c.Writer.Header().Get("Set-Cookie"))
 }
 
 func TestContextGetCookie(t *testing.T) {