From bbe1cb1d295b8e8c96b28ac888c34a3fa7280899 Mon Sep 17 00:00:00 2001
From: Bruno Carlin <bruno.carlin@waarp.org>
Date: Fri, 3 Jun 2022 11:00:43 +0200
Subject: [PATCH] fix: syslog and file backends always returned errors on write

---
 backend.go              |  8 +++++--
 backend_syslog_linux.go |  6 +++++-
 backend_test.go         | 48 +++++++++++++++++++++++++++++++++++++++++
 go.mod                  |  2 ++
 go.sum                  | 10 +++++++++
 5 files changed, 71 insertions(+), 3 deletions(-)
 create mode 100644 backend_test.go
 create mode 100644 go.sum

diff --git a/backend.go b/backend.go
index e1e21d6..695b45d 100644
--- a/backend.go
+++ b/backend.go
@@ -76,9 +76,13 @@ func NewIoBackend(buf io.Writer) *FileBackend {
 
 func (b FileBackend) Write(r *Record) error {
 	text := b.formatter(r)
-	_, err := io.WriteString(b.l, text)
 
-	return fmt.Errorf("cannot write logs: %w", err)
+	_, err := io.WriteString(b.l, text)
+	if err != nil {
+		return fmt.Errorf("cannot write logs: %w", err)
+	}
+
+	return nil
 }
 
 // SetLevel changes the log level of the backend.
diff --git a/backend_syslog_linux.go b/backend_syslog_linux.go
index 7ab650a..970ac95 100644
--- a/backend_syslog_linux.go
+++ b/backend_syslog_linux.go
@@ -72,7 +72,11 @@ func (sb *SyslogBackend) Write(r *Record) error {
 		err = sb.w.Emerg(text)
 	}
 
-	return fmt.Errorf("cannot log to syslog: %w", err)
+	if err != nil {
+		return fmt.Errorf("cannot log to syslog: %w", err)
+	}
+
+	return nil
 }
 
 // SetFormatter defines the formatter for this backend.
diff --git a/backend_test.go b/backend_test.go
new file mode 100644
index 0000000..3766ecd
--- /dev/null
+++ b/backend_test.go
@@ -0,0 +1,48 @@
+package logging
+
+import (
+	"bytes"
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type WriteErrorBuffer struct{}
+
+func (*WriteErrorBuffer) Write(_ []byte) (int, error) {
+	return 0, errors.New("cannot write")
+}
+
+func TestFileBackendWrite(t *testing.T) {
+	t.Parallel()
+
+	t.Run("It should write the logs to the buffer", func(t *testing.T) {
+		t.Parallel()
+
+		buf := new(bytes.Buffer)
+		b := NewIoBackend(buf)
+
+		err := b.Write(&Record{
+			Level:   Info,
+			Message: "my log line",
+		})
+
+		require.NoError(t, err)
+		require.Contains(t, buf.String(), "my log line")
+	})
+
+	t.Run("It should return an error if it cannot write the log", func(t *testing.T) {
+		t.Parallel()
+
+		buf := new(WriteErrorBuffer)
+		b := NewIoBackend(buf)
+
+		err := b.Write(&Record{
+			Level:   Info,
+			Message: "my log line",
+		})
+
+		require.Error(t, err)
+	})
+}
diff --git a/go.mod b/go.mod
index 72e56a7..0530919 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module code.bcarlin.xyz/go/logging
 
 go 1.13
+
+require github.com/stretchr/testify v1.7.1 // indirect
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..ed3bf3c
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=