allow custom splinter logger for middleware

pkg/middleware/logger.go

@@ -29,16 +29,38 @@ func (s *statusRecorder) Write(b []byte) (int, error) {
 	return s.ResponseWriter.Write(b)
 }
 
+// Logger uses splinter.Default() resolved at request time.
 func Logger(next http.Handler) http.Handler {
+	return loggerHandler(nil, next)
+}
+
+// LoggerWith returns a Logger middleware backed by the given splinter logger.
+// Pass nil to fall back to splinter.Default() (equivalent to Logger).
+func LoggerWith(l *splinter.Logger) Middleware {
+	return func(next http.Handler) http.Handler {
+		return loggerHandler(l, next)
+	}
+}
+
+func loggerHandler(l *splinter.Logger, next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		start := time.Now()
 		rec := &statusRecorder{ResponseWriter: w, status: http.StatusOK}
 		next.ServeHTTP(rec, r)
+		if l == nil {
 			splinter.Info("http.request",
 				"method", r.Method,
 				"path", r.URL.Path,
 				"status", rec.status,
 				"duration", time.Since(start),
 			)
+			return
+		}
+		l.Info("http.request",
+			"method", r.Method,
+			"path", r.URL.Path,
+			"status", rec.status,
+			"duration", time.Since(start),
+		)
 	})
 }

pkg/middleware/logger_test.go

@@ -56,3 +56,37 @@ func TestLoggerDefaultStatusOK(t *testing.T) {
 		t.Errorf("expected default status 200 in log, got %q", buf.String())
 	}
 }
+
+func TestLoggerWith(t *testing.T) {
+	defaultBuf := captureSplinter(t)
+
+	var customBuf bytes.Buffer
+	custom := splinter.New(splinter.WithStream(splinter.NewConsoleStream(
+		splinter.ConsoleJSON,
+		splinter.LevelDebug,
+		splinter.ConsoleWriter(&customBuf),
+	)))
+
+	h := LoggerWith(custom)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusAccepted)
+	}))
+	h.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest(http.MethodPost, "/x", nil))
+
+	if !strings.Contains(customBuf.String(), `"path":"/x"`) {
+		t.Errorf("custom logger did not receive record: %q", customBuf.String())
+	}
+	if defaultBuf.Len() != 0 {
+		t.Errorf("default logger should not have been written to, got: %q", defaultBuf.String())
+	}
+}
+
+func TestLoggerWithNilFallsBackToDefault(t *testing.T) {
+	buf := captureSplinter(t)
+
+	h := LoggerWith(nil)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+	h.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest(http.MethodGet, "/y", nil))
+
+	if !strings.Contains(buf.String(), `"path":"/y"`) {
+		t.Errorf("nil logger should fall back to splinter.Default(): %q", buf.String())
+	}
+}