Add image load.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/util/image_test.go

@@ -0,0 +1,84 @@
+/*
+Copyright 2017 The Kubernetes 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 util
+
+import (
+	"testing"
+
+	"github.com/containerd/containerd/reference"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNormalizeImageRef(t *testing.T) {
+	for _, test := range []struct {
+		input  string
+		expect string
+	}{
+		{ // has nothing
+			input:  "busybox",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // only has tag
+			input:  "busybox:latest",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // only has digest
+			input:  "busybox@sha256:e6693c20186f837fc393390135d8a598a96a833917917789d63766cab6c59582",
+			expect: "docker.io/library/busybox@sha256:e6693c20186f837fc393390135d8a598a96a833917917789d63766cab6c59582",
+		},
+		{ // only has path
+			input:  "library/busybox",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // only has hostname
+			input:  "docker.io/busybox",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // has no tag
+			input:  "docker.io/library/busybox",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // has no path
+			input:  "docker.io/busybox:latest",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // has no hostname
+			input:  "library/busybox:latest",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // full reference
+			input:  "docker.io/library/busybox:latest",
+			expect: "docker.io/library/busybox:latest",
+		},
+		{ // gcr reference
+			input:  "gcr.io/library/busybox",
+			expect: "gcr.io/library/busybox:latest",
+		},
+		{ // both tag and digest
+			input:  "gcr.io/library/busybox:latest@sha256:e6693c20186f837fc393390135d8a598a96a833917917789d63766cab6c59582",
+			expect: "gcr.io/library/busybox@sha256:e6693c20186f837fc393390135d8a598a96a833917917789d63766cab6c59582",
+		},
+	} {
+		t.Logf("TestCase %q", test.input)
+		normalized, err := NormalizeImageRef(test.input)
+		assert.NoError(t, err)
+		output := normalized.String()
+		assert.Equal(t, test.expect, output)
+		_, err = reference.Parse(output)
+		assert.NoError(t, err, "%q should be containerd supported reference", output)
+	}
+}