[Refactor] Move image/ to internal

This PR is an effort towards reducing the public surface
of APIs. It move image/ to internal/image

Signed-off-by: Varsha Prasad Narsing <varshaprasad96@gmail.com>
(cherry picked from commit 1f5890709fdc17de6f44f42b5138dd0f7e64bc74)

api/internal/image/image_test.go

@@ -0,0 +1,126 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package image_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/api/internal/image"
+)
+
+func TestIsImageMatched(t *testing.T) {
+	testCases := []struct {
+		testName  string
+		value     string
+		name      string
+		isMatched bool
+	}{
+		{
+			testName:  "identical",
+			value:     "nginx",
+			name:      "nginx",
+			isMatched: true,
+		},
+		{
+			testName:  "name is match with tag",
+			value:     "nginx:12345",
+			name:      "nginx",
+			isMatched: true,
+		},
+		{
+			testName:  "name is match with digest",
+			value:     "nginx@sha256:xyz",
+			name:      "nginx",
+			isMatched: true,
+		},
+		{
+			testName:  "name is match with tag and digest",
+			value:     "nginx:12345@sha256:xyz",
+			name:      "nginx",
+			isMatched: true,
+		},
+		{
+			testName:  "name is not a match",
+			value:     "apache:12345",
+			name:      "nginx",
+			isMatched: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.testName, func(t *testing.T) {
+			assert.Equal(t, tc.isMatched, image.IsImageMatched(tc.value, tc.name))
+		})
+	}
+}
+
+func TestSplit(t *testing.T) {
+	testCases := []struct {
+		testName string
+		value    string
+		name     string
+		tag      string
+		digest   string
+	}{
+		{
+			testName: "no tag",
+			value:    "nginx",
+			name:     "nginx",
+			tag:      "",
+			digest:   "",
+		},
+		{
+			testName: "with tag",
+			value:    "nginx:1.2.3",
+			name:     "nginx",
+			tag:      "1.2.3",
+			digest:   "",
+		},
+		{
+			testName: "with digest",
+			value:    "nginx@sha256:12345",
+			name:     "nginx",
+			tag:      "",
+			digest:   "sha256:12345",
+		},
+		{
+			testName: "with tag and digest",
+			value:    "nginx:1.2.3@sha256:12345",
+			name:     "nginx",
+			tag:      "1.2.3",
+			digest:   "sha256:12345",
+		},
+		{
+			testName: "with domain",
+			value:    "docker.io/nginx:1.2.3",
+			name:     "docker.io/nginx",
+			tag:      "1.2.3",
+			digest:   "",
+		},
+		{
+			testName: "with domain and port",
+			value:    "foo.com:443/nginx:1.2.3",
+			name:     "foo.com:443/nginx",
+			tag:      "1.2.3",
+			digest:   "",
+		},
+		{
+			testName: "with domain, port, tag and digest",
+			value:    "foo.com:443/nginx:1.2.3@sha256:12345",
+			name:     "foo.com:443/nginx",
+			tag:      "1.2.3",
+			digest:   "sha256:12345",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.testName, func(t *testing.T) {
+			name, tag, digest := image.Split(tc.value)
+			assert.Equal(t, tc.name, name)
+			assert.Equal(t, tc.tag, tag)
+			assert.Equal(t, tc.digest, digest)
+		})
+	}
+}