Shift Logger.Log contract to "should not actually exit or panic"

logger.go

@@ -50,6 +50,11 @@ type Logger interface {
 
 	// Log a message at the given level. Messages include any context that's
 	// accumulated on the logger, as well as any fields added at the log site.
+	//
+	// Calling Panic should panic(), calling Fatal() should terminate the
+	// process, but calling Log(PanicLevel, ...) or Log(FatalLevel, ...) should
+	// not. It may not be possible for compatibility wrappers to comply with
+	// this last part (e.g. the bark wrapper).
 	Log(Level, string, ...Field)
 	Debug(string, ...Field)
 	Info(string, ...Field)
@@ -99,14 +104,7 @@ func (log *logger) Check(lvl Level, msg string) *CheckedMessage {
 }
 
 func (log *logger) Log(lvl Level, msg string, fields ...Field) {
-	switch lvl {
-	case PanicLevel:
-		log.Panic(msg, fields...)
-	case FatalLevel:
-		log.Fatal(msg, fields...)
-	default:
-		log.log(lvl, msg, fields)
-	}
+	log.log(lvl, msg, fields)
 }
 
 func (log *logger) Debug(msg string, fields ...Field) {

logger_test.go

@@ -186,15 +186,41 @@ func TestJSONLoggerLog(t *testing.T) {
 	})
 
 	withJSONLogger(t, nil, func(logger Logger, buf *testBuffer) {
-		assert.Panics(t, func() { logger.Log(PanicLevel, "foo") }, "Expected logging at Panic level to panic.")
+		assert.NotPanics(t, func() { logger.Log(PanicLevel, "foo") }, "Expected logging at Panic level to not panic.")
 		assert.Equal(t, `{"level":"panic","msg":"foo"}`, buf.Stripped(), "Unexpected output from panic-level Log.")
 	})
 
-	stub := stubExit()
-	defer stub.Unstub()
 	withJSONLogger(t, nil, func(logger Logger, buf *testBuffer) {
+		assert.Panics(t, func() { logger.Panic("bar") }, "Expected logger.Panic to panic.")
+		assert.Equal(t, `{"level":"panic","msg":"bar"}`, buf.Stripped(), "Unexpected output from panic-level Log.")
+	})
+
+	withJSONLogger(t, nil, func(logger Logger, buf *testBuffer) {
+		assert.Panics(t, func() { logger.Check(PanicLevel, "baz").Write() }, "Expected checked logging at Panic level to panic.")
+		assert.Equal(t, `{"level":"panic","msg":"baz"}`, buf.Stripped(), "Unexpected output from panic-level Log.")
+	})
+
+	withJSONLogger(t, nil, func(logger Logger, buf *testBuffer) {
+		stub := stubExit()
+		defer stub.Unstub()
 		logger.Log(FatalLevel, "foo")
 		assert.Equal(t, `{"level":"fatal","msg":"foo"}`, buf.Stripped(), "Unexpected output from fatal-level Log.")
+		stub.AssertNoExit(t)
+	})
+
+	withJSONLogger(t, nil, func(logger Logger, buf *testBuffer) {
+		stub := stubExit()
+		defer stub.Unstub()
+		logger.Check(FatalLevel, "bar").Write()
+		assert.Equal(t, `{"level":"fatal","msg":"bar"}`, buf.Stripped(), "Unexpected output from fatal-level Log.")
+		stub.AssertStatus(t, 1)
+	})
+
+	withJSONLogger(t, nil, func(logger Logger, buf *testBuffer) {
+		stub := stubExit()
+		defer stub.Unstub()
+		logger.Fatal("baz")
+		assert.Equal(t, `{"level":"fatal","msg":"baz"}`, buf.Stripped(), "Unexpected output from fatal-level Log.")
 		stub.AssertStatus(t, 1)
 	})
 }

zbark/debark.go

@@ -53,6 +53,8 @@ func (z *zapper) DFatal(msg string, fields ...zap.Field) {
 }
 
 func (z *zapper) Log(l zap.Level, msg string, fields ...zap.Field) {
+	// NOTE: logging at panic and fatal level actually panic and exit the
+	// process, meaning that bark loggers cannot compose well.
 	switch l {
 	case zap.PanicLevel, zap.FatalLevel:
 	default: