wal: add DetectVersion test

wal/util.go

@@ -37,11 +37,11 @@ const (
 )
 
 func DetectVersion(dirpath string) (WalVersion, error) {
-	if _, err := os.Stat(dirpath); os.IsNotExist(err) {
-		return WALNotExist, nil
-	}
 	names, err := fileutil.ReadDir(dirpath)
 	if err != nil {
+		if os.IsNotExist(err) {
+			err = nil
+		}
 		// Error reading the directory
 		return WALNotExist, err
 	}

wal/util_test.go

@@ -0,0 +1,79 @@
+/*
+   Copyright 2014 CoreOS, Inc.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package wal
+
+import (
+	"io/ioutil"
+	"os"
+	"path"
+	"strings"
+	"testing"
+)
+
+func TestDetectVersion(t *testing.T) {
+	tests := []struct {
+		names []string
+		wver  WalVersion
+	}{
+		{[]string{}, WALNotExist},
+		{[]string{"snap/", "wal/", "wal/1"}, WALv0_5},
+		{[]string{"snapshot/", "conf", "log"}, WALv0_4},
+		{[]string{"weird"}, WALUnknown},
+		{[]string{"snap/", "wal/"}, WALUnknown},
+	}
+	for i, tt := range tests {
+		p := mustMakeDir(t, tt.names...)
+		ver, err := DetectVersion(p)
+		if ver != tt.wver {
+			t.Errorf("#%d: version = %s, want %s", i, ver, tt.wver)
+		}
+		if err != nil {
+			t.Errorf("#%d: err = %s, want nil", i, err)
+		}
+		os.RemoveAll(p)
+	}
+
+	// detect on non-exist directory
+	v, err := DetectVersion(path.Join(os.TempDir(), "waltest", "not-exist"))
+	if v != WALNotExist {
+		t.Errorf("#non-exist: version = %s, want %s", v, WALNotExist)
+	}
+	if err != nil {
+		t.Errorf("#non-exist: err = %s, want %s", v, WALNotExist)
+	}
+}
+
+// mustMakeDir builds the directory that contains files with the given
+// names. If the name ends with '/', it is created as a directory.
+func mustMakeDir(t *testing.T, names ...string) string {
+	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, n := range names {
+		if strings.HasSuffix(n, "/") {
+			if err := os.MkdirAll(path.Join(p, n), 0700); err != nil {
+				t.Fatal(err)
+			}
+		} else {
+			if _, err := os.Create(path.Join(p, n)); err != nil {
+				t.Fatal(err)
+			}
+		}
+	}
+	return p
+}