Handle Empty Messages (#82)

* ignore common files and directories

* add test

* skip message if empty

* formatting

.gitignore

@@ -11,3 +11,7 @@ examples/new/new
 examples/options/options
 examples/oven/oven
 examples/temperature/temperature
+
+.vscode
+.history
+go.work

logger.go

@@ -79,15 +79,17 @@ func (l *Logger) log(level Level, msg interface{}, keyvals ...interface{}) {
 	}
 
 	if msg != nil {
-		m := fmt.Sprint(msg)
-		kvs = append(kvs, MessageKey, m)
+		if m := fmt.Sprint(msg); m != "" {
+			kvs = append(kvs, MessageKey, m)
+		}
 	}
 
 	// append logger fields
 	kvs = append(kvs, l.fields...)
 	if len(l.fields)%2 != 0 {
 		kvs = append(kvs, ErrMissingValue)
 	}
+
 	// append the rest
 	kvs = append(kvs, keyvals...)
 	if len(keyvals)%2 != 0 {

logger_test.go

@@ -129,6 +129,47 @@ func TestLogFormatter(t *testing.T) {
 	}
 }
 
+func TestEmptyMessage(t *testing.T) {
+	var buf bytes.Buffer
+	l := New(&buf)
+	cases := []struct {
+		name     string
+		expected string
+		msg      string
+		fields   []interface{}
+		kvs      []interface{}
+	}{
+		{
+			name:     "empty message nil fields",
+			expected: "INFO\n",
+			msg:      "",
+			fields:   nil,
+			kvs:      nil,
+		},
+		{
+			name:     "empty message with fields",
+			expected: "INFO foo=bar\n",
+			msg:      "",
+			fields:   []interface{}{"foo", "bar"},
+			kvs:      nil,
+		},
+		{
+			name:     "empty message with fields & kvs",
+			expected: "INFO foo=bar foobar=baz\n",
+			msg:      "",
+			fields:   []interface{}{"foo", "bar"},
+			kvs:      []interface{}{"foobar", "baz"},
+		},
+	}
+	for _, c := range cases {
+		buf.Reset()
+		t.Run(c.name, func(t *testing.T) {
+			l.With(c.fields...).Info(c.msg, c.kvs...)
+			assert.Equal(t, c.expected, buf.String())
+		})
+	}
+}
+
 func TestLogWithPrefix(t *testing.T) {
 	var buf bytes.Buffer
 	cases := []struct {

text.go

@@ -143,46 +143,61 @@ func needsQuoting(str string) bool {
 }
 
 func (l *Logger) textFormatter(keyvals ...interface{}) {
-	for i := 0; i < len(keyvals); i += 2 {
+	lenKeyvals := len(keyvals)
+
+	for i := 0; i < lenKeyvals; i += 2 {
+		firstKey := i == 0
+		moreKeys := i < lenKeyvals-2
+
 		switch keyvals[i] {
 		case TimestampKey:
 			if t, ok := keyvals[i+1].(time.Time); ok {
 				ts := t.Format(l.timeFormat)
 				ts = TimestampStyle.Renderer(l.re).Render(ts)
+				if !firstKey {
+					l.b.WriteByte(' ')
+				}
 				l.b.WriteString(ts)
-				l.b.WriteByte(' ')
 			}
 		case LevelKey:
 			if level, ok := keyvals[i+1].(Level); ok {
 				lvl := levelStyle(level).Renderer(l.re).String()
+				if !firstKey {
+					l.b.WriteByte(' ')
+				}
 				l.b.WriteString(lvl)
-				l.b.WriteByte(' ')
 			}
 		case CallerKey:
 			if caller, ok := keyvals[i+1].(string); ok {
 				caller = fmt.Sprintf("<%s>", caller)
 				caller = CallerStyle.Renderer(l.re).Render(caller)
+				if !firstKey {
+					l.b.WriteByte(' ')
+				}
 				l.b.WriteString(caller)
-				l.b.WriteByte(' ')
 			}
 		case PrefixKey:
 			if prefix, ok := keyvals[i+1].(string); ok {
 				prefix = PrefixStyle.Renderer(l.re).Render(prefix + ":")
+				if !firstKey {
+					l.b.WriteByte(' ')
+				}
 				l.b.WriteString(prefix)
-				l.b.WriteByte(' ')
 			}
 		case MessageKey:
 			if msg := keyvals[i+1]; msg != nil {
 				m := fmt.Sprint(msg)
 				m = MessageStyle.Renderer(l.re).Render(m)
+				if !firstKey {
+					l.b.WriteByte(' ')
+				}
 				l.b.WriteString(m)
 			}
 		default:
 			sep := separator
 			indentSep := indentSeparator
 			sep = SeparatorStyle.Renderer(l.re).Render(sep)
 			indentSep = SeparatorStyle.Renderer(l.re).Render(indentSep)
-			moreKeys := i < len(keyvals)-2
 			key := fmt.Sprint(keyvals[i])
 			val := fmt.Sprintf("%+v", keyvals[i+1])
 			raw := val == ""
@@ -215,19 +230,19 @@ func (l *Logger) textFormatter(keyvals ...interface{}) {
 				l.b.WriteString(key)
 				l.b.WriteString(sep + "\n")
 				l.writeIndent(&l.b, val, indentSep, moreKeys, actualKey)
-				// If there are more keyvals, separate them with a space.
-				if moreKeys {
+			} else if !raw && needsQuoting(val) {
+				if !firstKey {
 					l.b.WriteByte(' ')
 				}
-			} else if !raw && needsQuoting(val) {
-				l.b.WriteByte(' ')
 				l.b.WriteString(key)
 				l.b.WriteString(sep)
 				l.b.WriteString(valueStyle.Renderer(l.re).Render(fmt.Sprintf(`"%s"`,
 					escapeStringForOutput(val, true))))
 			} else {
 				val = valueStyle.Renderer(l.re).Render(val)
-				l.b.WriteByte(' ')
+				if !firstKey {
+					l.b.WriteByte(' ')
+				}
 				l.b.WriteString(key)
 				l.b.WriteString(sep)
 				l.b.WriteString(val)