package main

import (
	"bytes"
	"fmt"
	"io"
	"os"
	"strings"
	"testing"
)

type NopWriteCloser struct {
	io.Writer
}

func (NopWriteCloser) Close() error {
	return nil
}

func nopCloser(w io.Writer) io.WriteCloser {
	return NopWriteCloser{w}
}

func TestWriteFile(t *testing.T) {
	// t.Parallel() cannot be used

	// set the function pointer back to its original value
	// after we modify it for the test
	saveTestHarnessWriteFile := testHarnessWriteFile
	defer func() {
		testHarnessWriteFile = saveTestHarnessWriteFile
	}()

	var output []byte
	testHarnessWriteFile = func(_ string, in []byte, _ os.FileMode) error {
		output = in
		return nil
	}

	buf := &bytes.Buffer{}
	writePackageName(buf, "pkg")
	fmt.Fprintf(buf, "func hello() {}\n\n\nfunc world() {\nreturn\n}\n\n\n\n")

	if err := writeFile("", "", buf); err != nil {
		t.Error(err)
	}

	if string(output) != "package pkg\n\nfunc hello() {}\n\nfunc world() {\n\treturn\n}\n" {
		t.Errorf("Wrong output: %q", output)
	}
}

func TestFormatBuffer(t *testing.T) {
	t.Parallel()

	buf := &bytes.Buffer{}

	fmt.Fprintf(buf, "package pkg\n\nfunc() {a}\n")

	// Only test error case - happy case is taken care of by template test
	_, err := formatBuffer(buf)
	if err == nil {
		t.Error("want an error")
	}

	if txt := err.Error(); !strings.Contains(txt, ">>>> func() {a}") {
		t.Error("got:\n", txt)
	}
}