utils: move trace to utils

Without exposing `trace`, we can't set a target to enable tracing from
out of go-git.

Fixes: https://github.com/go-git/go-git/pull/916

1 files changed, 95 insertions, 0 deletions

diff --git a/utils/trace/trace_test.go b/utils/trace/trace_test.go
new file mode 100644
index 0000000..6f8f140
--- /dev/null
+++ b/utils/trace/trace_test.go
@@ -0,0 +1,95 @@
+package trace
+
+import (
+	"bytes"
+	"io"
+	"log"
+	"testing"
+)
+
+func TestMain(m *testing.M) {
+	defer SetLogger(newLogger())
+	if code := m.Run(); code != 0 {
+		panic(code)
+	}
+}
+
+func setUpTest(t testing.TB, buf *bytes.Buffer) {
+	t.Cleanup(func() {
+		if buf != nil {
+			buf.Reset()
+		}
+		SetTarget(0)
+	})
+	w := io.Discard
+	if buf != nil {
+		w = buf
+	}
+	SetLogger(log.New(w, "", 0))
+}
+
+func TestEmpty(t *testing.T) {
+	var buf bytes.Buffer
+	setUpTest(t, &buf)
+	General.Print("test")
+	if buf.String() != "" {
+		t.Error("expected empty string")
+	}
+}
+
+func TestOneTarget(t *testing.T) {
+	var buf bytes.Buffer
+	setUpTest(t, &buf)
+	SetTarget(General)
+	General.Print("test")
+	if buf.String() != "test\n" {
+		t.Error("expected 'test'")
+	}
+}
+
+func TestMultipleTargets(t *testing.T) {
+	var buf bytes.Buffer
+	setUpTest(t, &buf)
+	SetTarget(General | Packet)
+	General.Print("a")
+	Packet.Print("b")
+	if buf.String() != "a\nb\n" {
+		t.Error("expected 'a\nb\n'")
+	}
+}
+
+func TestPrintf(t *testing.T) {
+	var buf bytes.Buffer
+	setUpTest(t, &buf)
+	SetTarget(General)
+	General.Printf("a %d", 1)
+	if buf.String() != "a 1\n" {
+		t.Error("expected 'a 1\n'")
+	}
+}
+
+func TestDisabledMultipleTargets(t *testing.T) {
+	var buf bytes.Buffer
+	setUpTest(t, &buf)
+	SetTarget(General)
+	General.Print("a")
+	Packet.Print("b")
+	if buf.String() != "a\n" {
+		t.Error("expected 'a\n'")
+	}
+}
+
+func BenchmarkDisabledTarget(b *testing.B) {
+	setUpTest(b, nil)
+	for i := 0; i < b.N; i++ {
+		General.Print("test")
+	}
+}
+
+func BenchmarkEnabledTarget(b *testing.B) {
+	setUpTest(b, nil)
+	SetTarget(General)
+	for i := 0; i < b.N; i++ {
+		General.Print("test")
+	}
+}