From fb95ec76dc3b4900137cc92a8807882f155b75ed Mon Sep 17 00:00:00 2001
From: Doug Lauder <wiggin77@warpmail.net>
Date: Tue, 24 Aug 2021 17:36:56 -0300
Subject: [PATCH] added test logger support (#26)

---
 buffer.go               | 28 ++++++++++++++++
 targets/testing.go      | 72 +++++++++++++++++++++++++++++++++++++++++
 targets/testing_test.go | 20 ++++++++++++
 3 files changed, 120 insertions(+)
 create mode 100644 buffer.go
 create mode 100644 targets/testing.go
 create mode 100644 targets/testing_test.go

diff --git a/buffer.go b/buffer.go
new file mode 100644
index 0000000..42bf525
--- /dev/null
+++ b/buffer.go
@@ -0,0 +1,28 @@
+package logr
+
+import (
+	"bytes"
+	"sync"
+)
+
+// Buffer provides a thread-safe buffer useful for logging to memory in unit tests.
+type Buffer struct {
+	buf bytes.Buffer
+	mux sync.Mutex
+}
+
+func (b *Buffer) Read(p []byte) (n int, err error) {
+	b.mux.Lock()
+	defer b.mux.Unlock()
+	return b.buf.Read(p)
+}
+func (b *Buffer) Write(p []byte) (n int, err error) {
+	b.mux.Lock()
+	defer b.mux.Unlock()
+	return b.buf.Write(p)
+}
+func (b *Buffer) String() string {
+	b.mux.Lock()
+	defer b.mux.Unlock()
+	return b.buf.String()
+}
diff --git a/targets/testing.go b/targets/testing.go
new file mode 100644
index 0000000..ea3df70
--- /dev/null
+++ b/targets/testing.go
@@ -0,0 +1,72 @@
+package targets
+
+import (
+	"strings"
+	"sync"
+	"testing"
+
+	"github.com/mattermost/logr/v2"
+	"github.com/mattermost/logr/v2/formatters"
+)
+
+// Testing is a simple log target that writes to a (*testing.T) log.
+type Testing struct {
+	mux sync.Mutex
+	t   *testing.T
+}
+
+func NewTestingTarget(t *testing.T) *Testing {
+	return &Testing{
+		t: t,
+	}
+}
+
+// Init is called once to initialize the target.
+func (tt *Testing) Init() error {
+	return nil
+}
+
+// Write outputs bytes to this file target.
+func (tt *Testing) Write(p []byte, rec *logr.LogRec) (int, error) {
+	tt.mux.Lock()
+	defer tt.mux.Unlock()
+
+	if tt.t != nil {
+		s := strings.TrimSpace(string(p))
+		tt.t.Log(s)
+	}
+	return len(p), nil
+}
+
+// Shutdown is called once to free/close any resources.
+// Target queue is already drained when this is called.
+func (tt *Testing) Shutdown() error {
+	tt.mux.Lock()
+	defer tt.mux.Unlock()
+
+	tt.t = nil
+	return nil
+}
+
+// CreateTestLogger creates a logger for unit tests. Log records are output to `(*testing.T).Log`.
+// A new logger is returned along with a method to shutdown the new logger.
+func CreateTestLogger(t *testing.T, levels ...logr.Level) (logger logr.Logger, shutdown func() error) {
+	lgr, _ := logr.New()
+	filter := logr.NewCustomFilter(levels...)
+	formatter := &formatters.Plain{EnableCaller: true}
+	target := NewTestingTarget(t)
+
+	if err := lgr.AddTarget(target, "test", filter, formatter, 1000); err != nil {
+		t.Fail()
+	}
+	shutdown = func() error {
+		err := lgr.Shutdown()
+		if err != nil {
+			target.mux.Lock()
+			target.t.Error("error shutting down test logger", err)
+			target.mux.Unlock()
+		}
+		return err
+	}
+	return lgr.NewLogger(), shutdown
+}
diff --git a/targets/testing_test.go b/targets/testing_test.go
new file mode 100644
index 0000000..9e39718
--- /dev/null
+++ b/targets/testing_test.go
@@ -0,0 +1,20 @@
+package targets
+
+import (
+	"testing"
+
+	"github.com/mattermost/logr/v2"
+)
+
+func TestCreateTestLogger(t *testing.T) {
+	logger, shutdown := CreateTestLogger(t, logr.Debug, logr.Info)
+	defer shutdown()
+
+	for i := 0; i < 10; i++ {
+		if i%2 == 0 {
+			logger.Debug("counting even", logr.Int("count", i))
+		} else {
+			logger.Info("counting odd", logr.Int("count", i))
+		}
+	}
+}