added generic middleware

arrangehttp/middleware.go

@@ -0,0 +1,16 @@
+package arrangehttp
+
+// Middleware is the underlying type for decorators.
+type Middleware[T any] interface {
+ ~func(T) T
+}
+
+// ApplyMiddleware handles decorating a target type T. Middleware
+// executes in the order declared to this function.
+func ApplyMiddleware[T any, M Middleware[T]](t T, m ...M) T {
+ for i := len(m) - 1; i >= 0; i-- {
+ t = m[i](t)
+ }
+
+ return t
+}

arrangehttp/middleware_test.go

@@ -0,0 +1,44 @@
+package arrangehttp
+
+import (
+ "fmt"
+ "net/http"
+ "testing"
+
+ "github.com/stretchr/testify/suite"
+)
+
+type MiddlewareSuite struct {
+ suite.Suite
+}
+
+func (suite *MiddlewareSuite) testApplyMiddleware(count int) {
+ current := count - 1 // middleware themselves run in reverse order
+ middleware := make([]func(http.Handler) http.Handler, 0, count)
+ for i := 0; i < count; i++ {
+ i := i
+ middleware = append(middleware, func(actual http.Handler) http.Handler {
+ suite.Same(http.DefaultServeMux, actual)
+ suite.Equal(i, current)
+ current--
+ return actual
+ })
+ }
+
+ suite.Equal(
+ http.DefaultServeMux,
+ ApplyMiddleware[http.Handler](http.DefaultServeMux, middleware...),
+ )
+}
+
+func (suite *MiddlewareSuite) TestApplyMiddleware() {
+ for _, count := range []int{0, 1, 2, 5} {
+ suite.Run(fmt.Sprintf("count=%d", count), func() {
+ suite.testApplyMiddleware(count)
+ })
+ }
+}
+
+func TestMiddleware(t *testing.T) {
+ suite.Run(t, new(MiddlewareSuite))
+}