Function TestHttpFancyWriterReadFromByteCountWithTee

middleware/wrap_writer_test.go:94–111

TestHttpFancyWriterReadFromByteCountWithTee is a regression test for https://github.com/go-chi/chi/issues/1067. httpFancyWriter.ReadFrom was adding n to basicWriter.bytes even when the write went through basicWriter.Write (which already increments the counter), resulting in double-counting the bytes

(t *testing.T)

// write went through basicWriter.Write (which already increments the counter),
// resulting in double-counting the bytes when a Tee writer was set.
func TestHttpFancyWriterReadFromByteCountWithTee(t *testing.T) {
	original := &httptest.ResponseRecorder{
		HeaderMap: make(http.Header),
		Body:      new(bytes.Buffer),
	}
	f := &httpFancyWriter{basicWriter: basicWriter{ResponseWriter: original}}

	var teeBuf bytes.Buffer
	f.Tee(&teeBuf)

	const input = "hello world"
	n, err := f.ReadFrom(strings.NewReader(input))
	assertNoError(t, err)
	assertEqual(t, int64(len(input)), n)
	// Before the fix, BytesWritten() returned 22 (double-counted).
	assertEqual(t, len(input), f.BytesWritten())
	assertEqual(t, []byte(input), teeBuf.Bytes())
}