fix: do not import test packages in logp package (#309)

* fix: do not import test packages in logp package

logp is importing testing and zaptest which is linked in the
binary of apps using this library

move NewTestingLogger to a separate package and use WrapCore
zap option to replace the logger core with the testing logger

* lint: rename

Author: kruskall

logp/core.go

@@ -405,7 +405,7 @@ func DevelopmentSetup(options ...Option) error {
 // TestingSetup configures logging by calling DevelopmentSetup if and only if
 // verbose testing is enabled (as in 'go test -v').
 //
-// Deprecated: Prefer using localized loggers. Use logp.NewTestingLogger.
+// Deprecated: Prefer using localized loggers. Use logptest.NewTestingLogger.
 func TestingSetup(options ...Option) error {
 	// Use the flag to avoid a dependency on the testing package.
 	f := flag.Lookup("test.v")

logp/logger.go

@@ -21,17 +21,14 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"testing"
 
 	"go.elastic.co/ecszap"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
-	"go.uber.org/zap/zaptest"
 )
 
 // LogOption configures a Logger.
 type LogOption = zap.Option
-type LogTestOption = zaptest.LoggerOption
 
 // Logger logs messages to the configured output.
 type Logger struct {
@@ -76,13 +73,6 @@ func NewDevelopmentLogger(selector string, options ...LogOption) (*Logger, error
 	return &Logger{log, log.Sugar()}, nil
 }
 
-// NewTestingLogger returns a testing suitable logp.Logger.
-func NewTestingLogger(t *testing.T, selector string, options ...LogTestOption) *Logger {
-	log := zaptest.NewLogger(t, options...)
-	log = log.Named(selector)
-	return &Logger{log, log.Sugar()}
-}
-
 // NewInMemory returns a new in-memory logger along with the buffer to which it
 // logs. It's goroutine safe, but operating directly on the returned buffer is not.
 // This logger is primary intended for short and simple use-cases such as printing

logp/logptest/logptest.go

@@ -0,0 +1,41 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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 logptest
+
+import (
+	"testing"
+
+	"github.com/elastic/elastic-agent-libs/logp"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+	"go.uber.org/zap/zaptest"
+)
+
+// NewTestingLogger returns a testing suitable logp.Logger.
+func NewTestingLogger(t testing.TB, selector string, options ...logp.LogOption) *logp.Logger {
+	log := zaptest.NewLogger(t)
+	log = log.Named(selector)
+	options = append(options, zap.WrapCore(func(zapcore.Core) zapcore.Core {
+		return log.Core()
+	}))
+	logger, err := logp.NewDevelopmentLogger(selector, options...)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return logger
+}