test(06-09): add failing panic response regressions

- Exercise house and raw handlers that write secrets before panicking
- Cover successful explicit and implicit response commits

surf/router_test.go

@@ -92,6 +92,120 @@ func TestRawGroupPanicBare500(t *testing.T) {
 	}
 }
 
+func TestRecoverDiscardsPartialResponse(t *testing.T) {
+	const secretBody = "secret-partial"
+
+	t.Run("house", func(t *testing.T) {
+		r := New(nil)
+		r.Get("/panic", func(w http.ResponseWriter, _ *http.Request) {
+			w.Header().Set("X-Partial", "secret")
+			w.WriteHeader(http.StatusAccepted)
+			_, _ = w.Write([]byte(secretBody))
+			panic("secret internals")
+		})
+		h, err := r.compile()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/panic", nil))
+		if rec.Code != http.StatusInternalServerError {
+			t.Fatalf("status = %d", rec.Code)
+		}
+		if got := rec.Header().Get("Content-Type"); got != "application/json" {
+			t.Fatalf("Content-Type = %q", got)
+		}
+		if got := rec.Header().Get("X-Partial"); got != "" {
+			t.Fatalf("X-Partial leaked: %q", got)
+		}
+		const want = `{"error":true,"message":"Internal server error"}`
+		if got := rec.Body.String(); got != want {
+			t.Fatalf("body = %q, want %q", got, want)
+		}
+		if strings.Contains(rec.Body.String(), secretBody) {
+			t.Fatalf("partial body leaked: %q", rec.Body.String())
+		}
+	})
+
+	t.Run("raw", func(t *testing.T) {
+		r := New(nil)
+		r.GroupRaw("/oauth", nil, func(g pact.Router) {
+			g.Get("/panic", func(w http.ResponseWriter, _ *http.Request) {
+				w.Header().Set("X-Partial", "secret")
+				w.WriteHeader(http.StatusAccepted)
+				_, _ = w.Write([]byte(secretBody))
+				panic("secret internals")
+			})
+		})
+		h, err := r.compile()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/oauth/panic", nil))
+		if rec.Code != http.StatusInternalServerError {
+			t.Fatalf("status = %d", rec.Code)
+		}
+		if rec.Body.Len() != 0 {
+			t.Fatalf("body = %q", rec.Body.String())
+		}
+		if got := rec.Header().Get("Content-Type"); got != "" {
+			t.Fatalf("Content-Type = %q", got)
+		}
+		if got := rec.Header().Get("X-Partial"); got != "" {
+			t.Fatalf("X-Partial leaked: %q", got)
+		}
+		if strings.Contains(rec.Body.String(), secretBody) {
+			t.Fatalf("partial body leaked: %q", rec.Body.String())
+		}
+	})
+}
+
+func TestBufferedResponseCommitsSuccessfulOutput(t *testing.T) {
+	r := New(nil)
+	r.Get("/explicit", func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Add("X-Result", "one")
+		w.Header().Add("X-Result", "two")
+		w.WriteHeader(http.StatusCreated)
+		w.WriteHeader(http.StatusTeapot)
+		_, _ = w.Write([]byte("created"))
+	})
+	r.Get("/implicit", func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("X-Result", "implicit")
+		_, _ = w.Write([]byte("ok"))
+	})
+	h, err := r.compile()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/explicit", nil))
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("explicit status = %d", rec.Code)
+	}
+	if got := rec.Header().Values("X-Result"); len(got) != 2 || got[0] != "one" || got[1] != "two" {
+		t.Fatalf("explicit X-Result = %q", got)
+	}
+	if got := rec.Body.String(); got != "created" {
+		t.Fatalf("explicit body = %q", got)
+	}
+
+	rec = httptest.NewRecorder()
+	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/implicit", nil))
+	if rec.Code != http.StatusOK {
+		t.Fatalf("implicit status = %d", rec.Code)
+	}
+	if got := rec.Header().Get("X-Result"); got != "implicit" {
+		t.Fatalf("implicit X-Result = %q", got)
+	}
+	if got := rec.Body.String(); got != "ok" {
+		t.Fatalf("implicit body = %q", got)
+	}
+}
+
 func TestHouseMiddlewareDuplicateNameFailsBoot(t *testing.T) {
 	identity := func(next http.Handler) http.Handler { return next }
 	named := assemblePlugin{