Rename to IncreaseLevel, add tests

increase_level_test.go

@@ -0,0 +1,81 @@
+// Copyright (c) 2020 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 zap
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.uber.org/zap/zapcore"
+	"go.uber.org/zap/zaptest/observer"
+)
+
+func newLoggedEntry(level zapcore.Level, msg string) observer.LoggedEntry {
+	return observer.LoggedEntry{
+		Entry:   zapcore.Entry{Level: level, Message: msg},
+		Context: []zapcore.Field{},
+	}
+}
+
+func TestIncreaseLevelTryDecrease(t *testing.T) {
+	errorOut := &bytes.Buffer{}
+	opts := []Option{
+		ErrorOutput(zapcore.AddSync(errorOut)),
+	}
+	withLogger(t, WarnLevel, opts, func(logger *Logger, logs *observer.ObservedLogs) {
+		logger.Warn("original warn log")
+
+		debugLogger := logger.WithOptions(IncreaseLevel(DebugLevel))
+		debugLogger.Debug("ignored debug log")
+		debugLogger.Warn("increase level warn log")
+		debugLogger.Error("increase level error log")
+
+		assert.Equal(t, []observer.LoggedEntry{
+			newLoggedEntry(WarnLevel, "original warn log"),
+			newLoggedEntry(WarnLevel, "increase level warn log"),
+			newLoggedEntry(ErrorLevel, "increase level error log"),
+		}, logs.AllUntimed(), "unexpected logs")
+		assert.Equal(t, "failed to IncreaseLevel: invalid increase level, as info is allowed by increased level, but not by existing core", errorOut.String(), "unexpected error output")
+	})
+}
+
+func TestIncreaseLevel(t *testing.T) {
+	errorOut := &bytes.Buffer{}
+	opts := []Option{
+		ErrorOutput(zapcore.AddSync(errorOut)),
+	}
+	withLogger(t, WarnLevel, opts, func(logger *Logger, logs *observer.ObservedLogs) {
+		logger.Warn("original warn log")
+
+		errorLogger := logger.WithOptions(IncreaseLevel(ErrorLevel))
+		errorLogger.Debug("ignored debug log")
+		errorLogger.Warn("ignored warn log")
+		errorLogger.Error("increase level error log")
+
+		assert.Equal(t, []observer.LoggedEntry{
+			newLoggedEntry(WarnLevel, "original warn log"),
+			newLoggedEntry(ErrorLevel, "increase level error log"),
+		}, logs.AllUntimed(), "unexpected logs")
+
+		assert.Empty(t, errorOut.String(), "expect no error output")
+	})
+}

options.go

@@ -20,7 +20,11 @@
 
 package zap
 
-import "go.uber.org/zap/zapcore"
+import (
+	"fmt"
+
+	"go.uber.org/zap/zapcore"
+)
 
 // An Option configures a Logger.
 type Option interface {
@@ -108,9 +112,15 @@ func AddStacktrace(lvl zapcore.LevelEnabler) Option {
 	})
 }
 
-// IncreaseLevel increase the level of the logger.
+// IncreaseLevel increase the level of the logger. It has no effect if
+// the passed in level tries to decrease the level of the logger.
 func IncreaseLevel(lvl zapcore.LevelEnabler) Option {
-	return WrapCore(func(c zapcore.Core) zapcore.Core {
-		return zapcore.NewLevelCore(c, lvl)
+	return optionFunc(func(log *Logger) {
+		core, err := zapcore.NewIncreaseLevelCore(log.core, lvl)
+		if err != nil {
+			fmt.Fprintf(log.errorOutput, "failed to IncreaseLevel: %v", err)
+		} else {
+			log.core = core
+		}
 	})
 }

zapcore/level_filter.go → zapcore/increase_level.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Uber Technologies, Inc.
+// Copyright (c) 2020 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
@@ -20,16 +20,25 @@
 
 package zapcore
 
+import "fmt"
+
 type levelFilterCore struct {
 	Core
 	level LevelEnabler
 }
 
-// NewLevelCore creates a core that can be used to increase the level of an existing
-// Core. It cannot be used to decrease the logging level, as it acts as a filter
-// before calling the underlying core.
-func NewLevelCore(core Core, level LevelEnabler) Core {
-	return &levelFilterCore{core, level}
+// NewIncreaseLevelCore creates a core that can be used to increase the level of
+// an existing Core. It cannot be used to decrease the logging level, as it acts
+// as a filter before calling the underlying core. If level decreases the log level,
+// an error is returned.
+func NewIncreaseLevelCore(core Core, level LevelEnabler) (Core, error) {
+	for l := _maxLevel; l >= _minLevel; l-- {
+		if !core.Enabled(l) && level.Enabled(l) {
+			return nil, fmt.Errorf("invalid increase level, as %v is allowed by increased level, but not by existing core", l)
+		}
+	}
+
+	return &levelFilterCore{core, level}, nil
 }
 
 func (c *levelFilterCore) Enabled(lvl Level) bool {

zapcore/increase_level_test.go

@@ -0,0 +1,102 @@
+// Copyright (c) 2020 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 zapcore_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	. "go.uber.org/zap/zapcore"
+	"go.uber.org/zap/zaptest/observer"
+)
+
+func TestIncreaseLevel(t *testing.T) {
+	tests := []struct {
+		coreLevel     Level
+		increaseLevel Level
+		wantErr       bool
+		wantLogLevels []Level
+	}{
+		{
+			coreLevel:     InfoLevel,
+			increaseLevel: DebugLevel,
+			wantErr:       true,
+		},
+		{
+			coreLevel:     InfoLevel,
+			increaseLevel: InfoLevel,
+		},
+		{
+			coreLevel:     InfoLevel,
+			increaseLevel: ErrorLevel,
+		},
+		{
+			coreLevel:     ErrorLevel,
+			increaseLevel: DebugLevel,
+			wantErr:       true,
+		},
+		{
+			coreLevel:     ErrorLevel,
+			increaseLevel: InfoLevel,
+			wantErr:       true,
+		},
+		{
+			coreLevel:     ErrorLevel,
+			increaseLevel: WarnLevel,
+			wantErr:       true,
+		},
+		{
+			coreLevel:     ErrorLevel,
+			increaseLevel: PanicLevel,
+		},
+	}
+
+	for _, tt := range tests {
+		msg := fmt.Sprintf("increase %v to %v", tt.coreLevel, tt.increaseLevel)
+		t.Run(msg, func(t *testing.T) {
+			logger, _ := observer.New(tt.coreLevel)
+
+			filteredLogger, err := NewIncreaseLevelCore(logger, tt.increaseLevel)
+			if tt.wantErr {
+				require.Error(t, err)
+				assert.Contains(t, err.Error(), "invalid increase level")
+				return
+			}
+
+			require.NoError(t, err)
+
+			for l := DebugLevel; l <= FatalLevel; l++ {
+				enabled := filteredLogger.Enabled(l)
+				ce := filteredLogger.Check(Entry{Level: l}, nil)
+
+				if l >= tt.increaseLevel {
+					assert.True(t, enabled, "expect %v to be enabled", l)
+					assert.NotNil(t, ce, "expect non-nil Check")
+				} else {
+					assert.False(t, enabled, "expect %v to be disabled", l)
+					assert.Nil(t, ce, "expect nil Check")
+				}
+			}
+		})
+	}
+}