output_test.go

// Copyright 2022 Twitter, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"bytes"
	"strings"
	"sync"
	"testing"

	"github.com/stretchr/testify/assert"
)

func Test_synchronizedWriter(t *testing.T) {
	var b bytes.Buffer
	sw := &synchronizedWriter{Writer: &b}
	n := 1000
	var wg sync.WaitGroup
	wg.Add(n)
	seq := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	for i := 0; i < n; i++ {
		go func() {
			sw.Write([]byte(seq))
			wg.Done()
		}()
	}
	wg.Wait()
	assert.Equal(t, 1000, strings.Count(b.String(), seq))
}

func Test_prefixingWriter(t *testing.T) {
	var b bytes.Buffer
	pw := &prefixingWriter{prefix: []byte{'p', ':', ' '}, w: &b}

	// single line (no trailing newline)
	n, err := pw.Write([]byte("hello"))
	assert.Equal(t, 5, n)
	assert.NoError(t, err)

	// multi line (no trailing newline) - continuation to single line + new line
	n, err = pw.Write([]byte("a\nb"))
	assert.Equal(t, 3, n)
	assert.NoError(t, err)
	assert.Equal(t, `p: helloa
`, b.String())

	n, err = pw.Write([]byte("eof\n"))
	assert.Equal(t, 4, n)
	assert.NoError(t, err)

	assert.Equal(t, `p: helloa
p: beof
`, // expected trailing newline
		b.String())
}

func Test_prefixingWriter_flushing(t *testing.T) {
	var b bytes.Buffer
	pw := &prefixingWriter{prefix: []byte{'x'}, w: &b}

	_, err := pw.Write([]byte("line1\n"))
	assert.NoError(t, err)
	assert.Equal(t, "xline1\n", b.String())

	// incomplete line
	_, err = pw.Write([]byte("line2"))
	assert.NoError(t, err)
	assert.NoError(t, pw.Close()) // close to flush
	assert.Equal(t, "xline1\nxline2\n", b.String())
}