tests: add test for adaptor

I noticed AdaptInfo missing test cases. I think this
func a bit important to test since we use this func
in other packages like content, store (walking), etc.

Signed-off-by: Furkan Turkal <furkan.turkal@trendyol.com>
Signed-off-by: Furkan <furkan.turkal@trendyol.com>

content/adaptor_test.go

@@ -0,0 +1,89 @@
+/*
+   Copyright The containerd Authors.
+
+   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 content
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAdaptInfo(t *testing.T) {
+	tests := []struct {
+		name        string
+		info        Info
+		fieldpath   []string
+		wantValue   string
+		wantPresent bool
+	}{
+		{
+			"empty fieldpath",
+			Info{},
+			[]string{},
+			"",
+			false,
+		},
+		{
+			"digest fieldpath",
+			Info{
+				Digest: "foo",
+			},
+			[]string{"digest"},
+			"foo",
+			true,
+		},
+		{
+			"size fieldpath",
+			Info{},
+			[]string{"size"},
+			"",
+			false,
+		},
+		{
+			"labels fieldpath",
+			Info{
+				Labels: map[string]string{
+					"foo": "bar",
+				},
+			},
+			[]string{"labels", "foo"},
+			"bar",
+			true,
+		},
+		{
+			"labels join fieldpath",
+			Info{
+				Labels: map[string]string{
+					"foo.bar.qux": "quux",
+				},
+			},
+			[]string{"labels", "foo", "bar", "qux"},
+			"quux",
+			true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			adaptInfo := AdaptInfo(tt.info)
+
+			value, present := adaptInfo.Field(tt.fieldpath)
+
+			assert.Equal(t, tt.wantValue, value)
+			assert.Equal(t, tt.wantPresent, present)
+		})
+	}
+}