From 4b989151ed7008c2412b94ed37bf4c974b33b6f7 Mon Sep 17 00:00:00 2001
From: Anton Kaliaev <anton.kalyaev@gmail.com>
Date: Mon, 6 Nov 2017 14:18:42 -0500
Subject: [PATCH] log logger's errors (Refs #29)

---
 log/tm_logger.go      | 15 ++++++++++++---
 log/tm_logger_test.go | 14 ++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/log/tm_logger.go b/log/tm_logger.go
index dc6932dd..d49e8d22 100644
--- a/log/tm_logger.go
+++ b/log/tm_logger.go
@@ -52,19 +52,28 @@ func NewTMLoggerWithColorFn(w io.Writer, colorFn func(keyvals ...interface{}) te
 // Info logs a message at level Info.
 func (l *tmLogger) Info(msg string, keyvals ...interface{}) {
 	lWithLevel := kitlevel.Info(l.srcLogger)
-	kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...)
+	if err := kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...); err != nil {
+		errLogger := kitlevel.Error(l.srcLogger)
+		kitlog.With(errLogger, msgKey, msg).Log("err", err)
+	}
 }
 
 // Debug logs a message at level Debug.
 func (l *tmLogger) Debug(msg string, keyvals ...interface{}) {
 	lWithLevel := kitlevel.Debug(l.srcLogger)
-	kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...)
+	if err := kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...); err != nil {
+		errLogger := kitlevel.Error(l.srcLogger)
+		kitlog.With(errLogger, msgKey, msg).Log("err", err)
+	}
 }
 
 // Error logs a message at level Error.
 func (l *tmLogger) Error(msg string, keyvals ...interface{}) {
 	lWithLevel := kitlevel.Error(l.srcLogger)
-	kitlog.With(lWithLevel, msgKey, msg).Log(keyvals...)
+	lWithMsg := kitlog.With(lWithLevel, msgKey, msg)
+	if err := lWithMsg.Log(keyvals...); err != nil {
+		lWithMsg.Log("err", err)
+	}
 }
 
 // With returns a new contextual logger with keyvals prepended to those passed
diff --git a/log/tm_logger_test.go b/log/tm_logger_test.go
index 8cd2f827..b2b600ad 100644
--- a/log/tm_logger_test.go
+++ b/log/tm_logger_test.go
@@ -1,12 +1,26 @@
 package log_test
 
 import (
+	"bytes"
 	"io/ioutil"
+	"strings"
 	"testing"
 
+	"github.com/go-logfmt/logfmt"
 	"github.com/tendermint/tmlibs/log"
 )
 
+func TestLoggerLogsItsErrors(t *testing.T) {
+	var buf bytes.Buffer
+
+	logger := log.NewTMLogger(&buf)
+	logger.Info("foo", "baz baz", "bar")
+	msg := strings.TrimSpace(buf.String())
+	if !strings.Contains(msg, logfmt.ErrInvalidKey.Error()) {
+		t.Errorf("Expected logger msg to contain ErrInvalidKey, got %s", msg)
+	}
+}
+
 func BenchmarkTMLoggerSimple(b *testing.B) {
 	benchmarkRunner(b, log.NewTMLogger(ioutil.Discard), baseInfoMessage)
 }