Add option to panic in test.NewNullLogger to allow testing of

calls to `Fatal*`

See #813

hooks/test/test.go

@@ -39,12 +39,24 @@ func NewLocal(logger *logrus.Logger) *Hook {
 
 }
 
+type TestOption func(logger *logrus.Logger)
+
+func FatalPanics(logger *logrus.Logger) {
+	logger.Exit = func(code int) {
+		panic(code)
+	}
+}
+
 // NewNullLogger creates a discarding logger and installs the test hook.
-func NewNullLogger() (*logrus.Logger, *Hook) {
+func NewNullLogger(options ...TestOption) (*logrus.Logger, *Hook) {
 
 	logger := logrus.New()
 	logger.Out = ioutil.Discard
 
+	for _, option := range options {
+		option(logger)
+	}
+
 	return logger, NewLocal(logger)
 
 }

hooks/test/test_test.go

@@ -71,3 +71,14 @@ func TestLoggingWithHooksRace(t *testing.T) {
 	entries := hook.AllEntries()
 	assert.Equal(100, len(entries))
 }
+
+func TestFatalWithPanic(t *testing.T) {
+	assert := assert.New(t)
+
+	logger, hook := NewNullLogger(FatalPanics)
+
+	assert.Nil(hook.LastEntry())
+	assert.Equal(0, len(hook.Entries))
+
+	assert.Panics(func() { logger.Fatal("something went wrong") })
+}