Implement setResponseBody

Co-authored-by: Hector Hurtado <hector.hurtado@bbva.com>

internal/server/data/resource.go

@@ -172,3 +172,12 @@ func setResponseCookies(w http.ResponseWriter, r *http.Request, h *model.Handler
 	c := &http.Cookie{Name: name, Value: string(vb)}
 	http.SetCookie(h.Writer, c)
 }
+
+func setResponseBody(w http.ResponseWriter, r *http.Request, h *model.Handler) {
+	if n, err := io.Copy(h.Writer, r.Body); err != nil {
+		if n > 0 {
+			panic("Truncated body")
+		}
+		w.WriteHeader(http.StatusInternalServerError)
+	}
+}

internal/server/data/resource_test.go

@@ -1262,3 +1262,70 @@ func TestSetResponseCookiesAddsValueToExistingCookie(t *testing.T) {
 }
 
 // TODO: Validate Cookie Name&Value encoding
+
+func TestSetResponseBody200sOnHappyPath(t *testing.T) {
+	h := model.Handler{
+		Request: httptest.NewRequest("POST", "/", nil),
+		Writer:  httptest.NewRecorder(),
+	}
+	r := httptest.NewRequest("PUT", "/", nil)
+	w := httptest.NewRecorder()
+
+	setResponseBody(w, r, &h)
+
+	res := w.Result()
+	if res.StatusCode != http.StatusOK {
+		t.Errorf("Status code mismatch. Expected: 200, Got: %d", res.StatusCode)
+	}
+}
+
+func TestSetResponseBodySetsTheResponseBody(t *testing.T) {
+	hw := httptest.NewRecorder()
+	h := model.Handler{
+		Request: httptest.NewRequest("POST", "/", nil),
+		Writer:  hw,
+	}
+	r := createMuxRequest("/handlers/HANDLERID/response/body", "/handlers/HANDLERID/response/body", "PUT", strings.NewReader("BAZ"))
+	w := httptest.NewRecorder()
+
+	setResponseBody(w, r, &h)
+
+	res := hw.Result()
+	if body, _ := ioutil.ReadAll(res.Body); string(body) != "BAZ" {
+		t.Errorf(`Body mismatch. Expected: "BAZ". Got: %q`, string(body))
+	}
+}
+
+func TestSetResponseBody500sWhenReaderFailsInFirstRead(t *testing.T) {
+	hw := httptest.NewRecorder()
+	h := model.Handler{
+		Request: httptest.NewRequest("POST", "/", nil),
+		Writer:  hw,
+	}
+	r := createMuxRequest("/handlers/HANDLERID/response/body", "/handlers/HANDLERID/response/body", "PUT", BadReader("Fail by design"))
+	w := httptest.NewRecorder()
+
+	setResponseBody(w, r, &h)
+
+	res := w.Result()
+	if res.StatusCode != http.StatusInternalServerError {
+		t.Errorf("Status code mismatch. Expected: 500, Got: %d", res.StatusCode)
+	}
+}
+
+func TestSetResponseBodyPanicsIfReaderFailsAfterFirstWrite(t *testing.T) {
+	hw := httptest.NewRecorder()
+	h := model.Handler{
+		Request: httptest.NewRequest("POST", "/", nil),
+		Writer:  hw,
+	}
+	r := createMuxRequest("/handlers/HANDLERID/response/body", "/handlers/HANDLERID/response/body", "PUT", ErrorOnSecondReadReader(strings.NewReader("FOO")))
+	w := httptest.NewRecorder()
+
+	defer func() {
+		if rec := recover(); rec == nil {
+			t.Error("Didn't panic")
+		}
+	}()
+	setResponseBody(w, r, &h)
+}