logger.go

// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package ztest

import (
	"bytes"
	"fmt"
	"time"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"go.uber.org/zap/zaptest"
)

// LoggerOption configures the test logger built by NewLogger.
type LoggerOption interface {
	applyLoggerOption(*loggerOptions)
}

type loggerOptions struct {
	Level      zapcore.LevelEnabler
	zapOptions []zap.Option
	encoder    zapcore.EncoderConfig
}

type loggerOptionFunc func(*loggerOptions)

func (f loggerOptionFunc) applyLoggerOption(opts *loggerOptions) {
	f(opts)
}

// Level controls which messages are logged by a test Logger built by
// NewLogger.
func Level(enab zapcore.LevelEnabler) LoggerOption {
	return loggerOptionFunc(func(opts *loggerOptions) {
		opts.Level = enab
	})
}

// WrapOptions adds zap.Option's to a test Logger built by NewLogger.
func WrapOptions(zapOpts ...zap.Option) LoggerOption {
	return loggerOptionFunc(func(opts *loggerOptions) {
		opts.zapOptions = zapOpts
	})
}

func shortLevel(l zapcore.Level) string {
	switch l {
	case zapcore.DebugLevel:
		return "DBG"
	case zapcore.InfoLevel:
		return "INF"
	case zapcore.FatalLevel:
		return "FTL"
	case zapcore.ErrorLevel:
		return "ERR"
	case zapcore.WarnLevel:
		return "WRN"
	case zapcore.DPanicLevel, zapcore.PanicLevel:
		return "PAN"
	default:
		return "UNK"
	}
}

// ShortLevelEncoder encodes level as single letter.
func ShortLevelEncoder(l zapcore.Level, enc zapcore.PrimitiveArrayEncoder) {
	enc.AppendString(shortLevel(l))
}

func ElapsedSecondsTimeEncoder(start time.Time) zapcore.TimeEncoder {
	return func(t time.Time, encoder zapcore.PrimitiveArrayEncoder) {
		elapsed := time.Since(start).Round(time.Millisecond).Seconds()
		encoder.AppendString(fmt.Sprintf("%4.2f", elapsed))
	}
}

// NewLogger builds a new Logger that logs all messages to the given
// testing.TB.
//
//	logger := ztest.NewLogger(t)
//
// Use this with a *testing.T or *testing.B to get logs which get printed only
// if a test fails or if you ran go test -v.
//
// The returned logger defaults to logging debug level messages and above.
// This may be changed by passing a ztest.Level during construction.
//
//	logger := ztest.NewLogger(t, ztest.Level(zap.WarnLevel))
//
// You may also pass zap.Option's to customize test logger.
//
//	logger := ztest.NewLogger(t, ztest.WrapOptions(zap.AddCaller()))
func NewLogger(t zaptest.TestingT, opts ...LoggerOption) *zap.Logger {
	encoder := zap.NewDevelopmentEncoderConfig()
	encoder.EncodeLevel = ShortLevelEncoder
	encoder.EncodeTime = ElapsedSecondsTimeEncoder(time.Now())

	cfg := loggerOptions{
		Level:   zapcore.DebugLevel,
		encoder: encoder,
	}
	for _, o := range opts {
		o.applyLoggerOption(&cfg)
	}

	writer := newTestingWriter(t)
	zapOptions := []zap.Option{
		// Send zap errors to the same writer and mark the test as failed if
		// that happens.
		zap.ErrorOutput(writer.WithMarkFailed(true)),
	}
	zapOptions = append(zapOptions, cfg.zapOptions...)

	return zap.New(
		zapcore.NewCore(
			zapcore.NewConsoleEncoder(cfg.encoder),
			writer,
			cfg.Level,
		),
		zapOptions...,
	)
}

// testingWriter is a WriteSyncer that writes to the given testing.TB.
type testingWriter struct {
	t zaptest.TestingT

	// If true, the test will be marked as failed if this testingWriter is
	// ever used.
	markFailed bool
}

func newTestingWriter(t zaptest.TestingT) testingWriter {
	return testingWriter{t: t}
}

// WithMarkFailed returns a copy of this testingWriter with markFailed set to
// the provided value.
func (w testingWriter) WithMarkFailed(v bool) testingWriter {
	w.markFailed = v
	return w
}

func (w testingWriter) Write(p []byte) (n int, err error) {
	n = len(p)

	// Strip trailing newline because t.Log always adds one.
	p = bytes.TrimRight(p, "\n")

	// Note: t.Log is safe for concurrent use.
	w.t.Logf("%s", p)
	if w.markFailed {
		w.t.Fail()
	}

	return n, nil
}

func (w testingWriter) Sync() error {
	return nil
}