feat: treat client closed requests as code 499 (#1350)

* feat: treat client closed requests as code 499

* chore: add comments

rest/handler/timeouthandler_test.go

@@ -1,6 +1,7 @@
 package handler
 
 import (
+	"context"
 	"io/ioutil"
 	"log"
 	"net/http"
@@ -39,6 +40,20 @@ func TestWithinTimeout(t *testing.T) {
 	assert.Equal(t, http.StatusOK, resp.Code)
 }
 
+func TestWithTimeoutTimedout(t *testing.T) {
+	timeoutHandler := TimeoutHandler(time.Millisecond)
+	handler := timeoutHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(time.Millisecond * 10)
+		w.Write([]byte(`foo`))
+		w.WriteHeader(http.StatusOK)
+	}))
+
+	req := httptest.NewRequest(http.MethodGet, "http://localhost", nil)
+	resp := httptest.NewRecorder()
+	handler.ServeHTTP(resp, req)
+	assert.Equal(t, http.StatusServiceUnavailable, resp.Code)
+}
+
 func TestWithoutTimeout(t *testing.T) {
 	timeoutHandler := TimeoutHandler(0)
 	handler := timeoutHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -50,3 +65,91 @@ func TestWithoutTimeout(t *testing.T) {
 	handler.ServeHTTP(resp, req)
 	assert.Equal(t, http.StatusOK, resp.Code)
 }
+
+func TestTimeoutPanic(t *testing.T) {
+	timeoutHandler := TimeoutHandler(time.Minute)
+	handler := timeoutHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		panic("foo")
+	}))
+
+	req := httptest.NewRequest(http.MethodGet, "http://localhost", nil)
+	resp := httptest.NewRecorder()
+	assert.Panics(t, func() {
+		handler.ServeHTTP(resp, req)
+	})
+}
+
+func TestTimeoutWroteHeaderTwice(t *testing.T) {
+	timeoutHandler := TimeoutHandler(time.Minute)
+	handler := timeoutHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(`hello`))
+		w.Header().Set("foo", "bar")
+		w.WriteHeader(http.StatusOK)
+	}))
+
+	req := httptest.NewRequest(http.MethodGet, "http://localhost", nil)
+	resp := httptest.NewRecorder()
+	handler.ServeHTTP(resp, req)
+	assert.Equal(t, http.StatusOK, resp.Code)
+}
+
+func TestTimeoutWriteBadCode(t *testing.T) {
+	timeoutHandler := TimeoutHandler(time.Minute)
+	handler := timeoutHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(1000)
+	}))
+
+	req := httptest.NewRequest(http.MethodGet, "http://localhost", nil)
+	resp := httptest.NewRecorder()
+	assert.Panics(t, func() {
+		handler.ServeHTTP(resp, req)
+	})
+}
+
+func TestTimeoutClientClosed(t *testing.T) {
+	timeoutHandler := TimeoutHandler(time.Minute)
+	handler := timeoutHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(1000)
+	}))
+
+	req := httptest.NewRequest(http.MethodGet, "http://localhost", nil)
+	ctx, cancel := context.WithCancel(context.Background())
+	req = req.WithContext(ctx)
+	cancel()
+	resp := httptest.NewRecorder()
+	handler.ServeHTTP(resp, req)
+	assert.Equal(t, statusClientClosedRequest, resp.Code)
+}
+
+func TestTimeoutPusher(t *testing.T) {
+	handler := &timeoutWriter{
+		w: mockedPusher{},
+	}
+
+	assert.Panics(t, func() {
+		handler.Push("any", nil)
+	})
+
+	handler = &timeoutWriter{
+		w: httptest.NewRecorder(),
+	}
+	assert.Equal(t, http.ErrNotSupported, handler.Push("any", nil))
+}
+
+type mockedPusher struct{}
+
+func (m mockedPusher) Header() http.Header {
+	panic("implement me")
+}
+
+func (m mockedPusher) Write(bytes []byte) (int, error) {
+	panic("implement me")
+}
+
+func (m mockedPusher) WriteHeader(statusCode int) {
+	panic("implement me")
+}
+
+func (m mockedPusher) Push(target string, opts *http.PushOptions) error {
+	panic("implement me")
+}