Merge pull request #2 from cabify/colega/trailing-newline-trimming

Trim trailing newline characters by default

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.1.0] - 2019-08-12
+### Added
+- Trailing newline character `\n` trimming enabled by default
+
 ## [1.0.0] - 2019-08-09
 ### Changes
 -  Initial version

configs.go

@@ -5,8 +5,17 @@ import "github.com/sirupsen/logrus"
 // Config holds the configuration to be used with WithConfig() configurer
 // This struct is useful to embed into configuration structs parsed with libraries like envconfig
 type Config struct {
-	Level  string        `default:"info"`
-	Fields logrus.Fields `default:"logger:stdlib"`
+	Level                   string        `default:"info"`
+	Fields                  logrus.Fields `default:"logger:stdlib"`
+	TrailingNewLineTrimming bool          `default:"true"`
+}
+
+// WithTrailingNewLineTrimming configures trailing newline trimming. This is true by default, because
+// log.Print adds a newline in the end of its messages, which does not make sense inside of a logrus log
+func WithTrailingNewLineTrimming(trim bool) Configurer {
+	return func(w *writer) {
+		w.trailingNewLineTrimming = trim
+	}
 }
 
 // WithLogger configures the logger with the one provided

configs_test.go

@@ -1,6 +1,7 @@
 package logrusiowriter
 
 import (
+	"bytes"
 	"testing"
 
 	"github.com/sirupsen/logrus"
@@ -51,4 +52,73 @@ func TestWithConfig(t *testing.T) {
 			t.Errorf("Error provided to OnLevelParseError should not be nil")
 		}
 	})
+
+	t.Run("trimming", func(t *testing.T) {
+		const newLineAppendedByLogrus = "\n"
+		for _, tc := range []struct {
+			desc     string
+			trimming bool
+			input    string
+			expected string
+		}{
+			{
+				desc:     "zerolength with trimming",
+				trimming: true,
+				input:    "",
+				expected: "level=info" + newLineAppendedByLogrus,
+			},
+			{
+				desc:     "zerolength without trimming",
+				trimming: false,
+				input:    "",
+				expected: "level=info" + newLineAppendedByLogrus,
+			},
+			{
+				desc:     "only newline with trimming",
+				trimming: true,
+				input:    "\n",
+				expected: "level=info" + newLineAppendedByLogrus,
+			},
+			{
+				desc:     "only newline without trimming",
+				trimming: false,
+				input:    "\n",
+				expected: `level=info msg="\n"` + newLineAppendedByLogrus,
+			},
+			{
+				desc:     "with trailing newline and trimming",
+				trimming: true,
+				input:    "message\n",
+				expected: "level=info msg=message" + newLineAppendedByLogrus,
+			},
+			{
+				desc:     "with trailing newline and no trimming",
+				trimming: false,
+				input:    "message\n",
+				expected: `level=info msg="message\n"` + newLineAppendedByLogrus,
+			},
+			{
+				desc:     "no newline with trimming",
+				trimming: true,
+				input:    "message",
+				expected: "level=info msg=message" + newLineAppendedByLogrus,
+			},
+		} {
+			t.Run(tc.desc, func(t *testing.T) {
+				buf := &bytes.Buffer{}
+
+				bufLogger := logrus.New()
+				bufLogger.SetOutput(buf)
+				bufLogger.Formatter.(*logrus.TextFormatter).DisableTimestamp = true
+
+				writer := New(WithLogger(bufLogger), WithTrailingNewLineTrimming(tc.trimming))
+
+				_, _ = writer.Write([]byte(tc.input))
+
+				if buf.String() != tc.expected {
+					t.Errorf("Unexpected output\nExpected: '%s'\nGot:      '%s'", tc.expected, buf.String())
+				}
+			})
+		}
+	})
 }

example_configs_test.go

@@ -79,6 +79,18 @@ func ExampleWithConfigInterface() {
 	// level=trace msg="Hello World!" config=interface
 }
 
+func ExampleWithNewLineTrimming() {
+	removeTimestampAndSetOutputToStdout(logrus.StandardLogger())
+
+	writer := logrusiowriter.New(
+		logrusiowriter.WithTrailingNewLineTrimming(true),
+	)
+
+	_, _ = fmt.Fprint(writer, "Hello World!\n")
+	// Output:
+	// level=info msg="Hello World!"
+}
+
 type configProvider struct{}
 
 func (configProvider) Level() logrus.Level { return logrus.TraceLevel }

example_writer_test.go

@@ -16,5 +16,5 @@ func ExampleNew() {
 	log.Printf("Standard log")
 
 	// Output:
-	// level=info msg="Standard log\n"
+	// level=info msg="Standard log"
 }

writer.go

@@ -11,9 +11,10 @@ import (
 // If no Configurers provided, the writer will log with Info level and no fields using the logrus.StandardLogger
 func New(cfg ...Configurer) io.Writer {
 	w := &writer{
-		logger: logrus.StandardLogger(),
-		level:  logrus.InfoLevel,
-		fields: make(map[string]interface{}),
+		logger:                  logrus.StandardLogger(),
+		level:                   logrus.InfoLevel,
+		fields:                  make(map[string]interface{}),
+		trailingNewLineTrimming: true,
 	}
 	for _, c := range cfg {
 		c(w)
@@ -27,13 +28,18 @@ type Configurer func(*writer)
 
 // writer implements io.Writer
 type writer struct {
-	logger logrus.FieldLogger
-	level  logrus.Level
-	fields map[string]interface{}
+	logger                  logrus.FieldLogger
+	level                   logrus.Level
+	fields                  map[string]interface{}
+	trailingNewLineTrimming bool
 }
 
 // Write will write with the logger, level and fields set in the writer
 func (w *writer) Write(bytes []byte) (int, error) {
+	l := len(bytes)
+	if w.trailingNewLineTrimming && l > 0 && bytes[l-1] == '\n' {
+		bytes = bytes[:l-1]
+	}
 	w.logger.WithFields(w.fields).Log(w.level, string(bytes))
-	return len(bytes), nil
+	return l, nil
 }