Rely on subset of testing.TB interface

This declares a TestingT interface which is a subset of the
functionality provided by testing.TB, and changes zaptest to rely on
that.

This also means that zaptest no longer imports the "testing" package.

zaptest/logger.go

@@ -21,8 +21,6 @@
 package zaptest
 
 import (
-	"testing"
-
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 )
@@ -32,7 +30,7 @@ import (
 //
 // 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.
-func NewLogger(t testing.TB) *zap.Logger {
+func NewLogger(t TestingT) *zap.Logger {
 	return NewLoggerAt(t, zapcore.DebugLevel)
 }
 
@@ -41,7 +39,7 @@ func NewLogger(t testing.TB) *zap.Logger {
 //
 // 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.
-func NewLoggerAt(t testing.TB, enab zapcore.LevelEnabler) *zap.Logger {
+func NewLoggerAt(t TestingT, enab zapcore.LevelEnabler) *zap.Logger {
 	return zap.New(zapcore.NewCore(
 		zapcore.NewConsoleEncoder(zapcore.EncoderConfig{
 			// EncoderConfig copied from zap.NewDevelopmentEncoderConfig.
@@ -64,7 +62,7 @@ func NewLoggerAt(t testing.TB, enab zapcore.LevelEnabler) *zap.Logger {
 }
 
 // testingWriter is a WriteSyncer that writes to the given testing.TB.
-type testingWriter struct{ t testing.TB }
+type testingWriter struct{ t TestingT }
 
 func (w testingWriter) Write(p []byte) (n int, err error) {
 	s := string(p)
@@ -75,7 +73,7 @@ func (w testingWriter) Write(p []byte) (n int, err error) {
 	}
 
 	// Note: t.Log is safe for concurrent use.
-	w.t.Log(s)
+	w.t.Logf("%s", s)
 	return len(p), nil
 }
 

zaptest/logger_test.go

@@ -76,14 +76,14 @@ func newTestLogSpy(t testing.TB) *testLogSpy {
 	return &testLogSpy{TB: t}
 }
 
-func (t *testLogSpy) Log(args ...interface{}) {
+func (t *testLogSpy) Logf(format string, args ...interface{}) {
 	// Log messages are in the format,
 	//
 	//   2017-10-27T13:03:01.000-0700	DEBUG	your message here	{data here}
 	//
 	// We strip the first part of these messages because we can't really test
 	// for the timestamp from these tests.
-	m := fmt.Sprint(args...)
+	m := fmt.Sprintf(format, args...)
 	m = m[strings.IndexByte(m, '\t')+1:]
 
 	// t.Log should be thread-safe.

zaptest/testingt.go

@@ -0,0 +1,38 @@
+// 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 zaptest
+
+// TestingT is a subset of the API provided by all *testing.T and *testing.B
+// objects.
+type TestingT interface {
+	// Logs the given message without failing the test.
+	Logf(string, ...interface{})
+
+	// Logs the given message and marks the test as failed.
+	Errorf(string, ...interface{})
+
+	// Marks the test as failed and stops execution of that test.
+	FailNow()
+}
+
+// Note: We currently only rely on Logf. We are including Errorf and FailNow
+// in the interface in anticipation of future need since we can't extend the
+// interface without a breaking change.

zaptest/testingt_test.go

@@ -0,0 +1,29 @@
+// 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 zaptest
+
+import "testing"
+
+// Just a compile-time test to ensure that TestingT matches the testing.TB
+// interface. We could do this in testingt.go but that would put a dependency
+// on the "testing" package from zaptest.
+
+var _ TestingT = (testing.TB)(nil)