Add tests for ID3v1 and ID3v1.1.

.gitignore

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+/id3v1_testdata.go

id3v1_test.go

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+// This file is subject to the CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+// license.  Its contents can be found at:
+// http://creativecommons.org/publicdomain/zero/1.0
+
+package tag
+
+import (
+	"bytes"
+	"testing"
+)
+
+//go:generate go-bindata -o id3v1_testdata.go -pkg tag -ignore .txt id3v1_test
+
+func TestReadID3v1Tags(t *testing.T) {
+	for _, name := range []string{
+		"id3v1_test/sample_usascii_v1.mp3",
+		"id3v1_test/sample_ms932_v1.mp3",
+		"id3v1_test/sample_utf8_v1.mp3"} {
+		doTest(name, 0, 30, t)
+	}
+	for _, name := range []string{
+		"id3v1_test/sample_usascii_v1.1.mp3",
+		"id3v1_test/sample_ms932_v1.1.mp3",
+		"id3v1_test/sample_utf8_v1.1.mp3"} {
+		doTest(name, 1, 28, t)
+	}
+}
+
+func doTest(name string, track int, length int, t *testing.T) {
+	mp3 := MustAsset(name)
+	metadata, _ := ReadID3v1Tags(bytes.NewReader(mp3))
+	if actual, total := metadata.Track(); actual != track || total != 0 {
+		t.Errorf("Track number for %s is (%d, %d) where (%d, 0) is expected.", name, actual, total, track)
+	}
+	comment := metadata.Raw()["comment"].(string)
+	if actual := len(comment); actual != length {
+		t.Errorf("Comment length for %s is %d where %d is expected", name, actual, length)
+	}
+}

id3v1_test/NOTICE.txt

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+All files in this directory are subject to the CC0 1.0 Universal (CC0 1.0)
+Public Domain Dedication license.  Its contents can be found at:
+http://creativecommons.org/publicdomain/zero/1.0