diff --git a/platforms/compare_test.go b/platforms/compare_test.go
new file mode 100644
index 000000000..638dd9bd6
--- /dev/null
+++ b/platforms/compare_test.go
@@ -0,0 +1,208 @@
+/*
+   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 platforms
+
+import (
+	"testing"
+)
+
+func TestOnly(t *testing.T) {
+	for _, tc := range []struct {
+		platform string
+		matches  map[bool][]string
+	}{
+		{
+			platform: "linux/amd64",
+			matches: map[bool][]string{
+				true: {
+					"linux/amd64",
+				},
+				false: {
+					"linux/386",
+					"linux/arm/v7",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/386",
+			matches: map[bool][]string{
+				true: {
+					"linux/386",
+				},
+				false: {
+					"linux/amd64",
+					"linux/arm/v7",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "windows/amd64",
+			matches: map[bool][]string{
+				true: {"windows/amd64"},
+				false: {
+					"linux/amd64",
+					"linux/arm/v7",
+					"linux/arm64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/arm/v8",
+			matches: map[bool][]string{
+				true: {
+					"linux/arm",
+					"linux/arm/v5",
+					"linux/arm/v6",
+					"linux/arm/v7",
+					"linux/arm/v8",
+				},
+				false: {
+					"linux/amd64",
+					"linux/arm/v4",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/arm/v7",
+			matches: map[bool][]string{
+				true: {
+					"linux/arm",
+					"linux/arm/v5",
+					"linux/arm/v6",
+					"linux/arm/v7",
+				},
+				false: {
+					"linux/amd64",
+					"linux/arm/v4",
+					"linux/arm/v8",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/arm/v6",
+			matches: map[bool][]string{
+				true: {
+					"linux/arm/v5",
+					"linux/arm/v6",
+				},
+				false: {
+					"linux/amd64",
+					"linux/arm",
+					"linux/arm/v4",
+					"linux/arm/v7",
+					"linux/arm/v8",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/arm/v5",
+			matches: map[bool][]string{
+				true: {
+					"linux/arm/v5",
+				},
+				false: {
+					"linux/amd64",
+					"linux/arm",
+					"linux/arm/v4",
+					"linux/arm/v6",
+					"linux/arm/v7",
+					"linux/arm/v8",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/arm/v4",
+			matches: map[bool][]string{
+				true: {
+					"linux/arm/v4",
+				},
+				false: {
+					"linux/amd64",
+					"linux/arm",
+					"linux/arm/v5",
+					"linux/arm/v6",
+					"linux/arm/v7",
+					"linux/arm/v8",
+					"linux/arm64",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+		{
+			platform: "linux/arm64",
+			matches: map[bool][]string{
+				true: {
+					"linux/arm64",
+					"linux/arm64/v8",
+				},
+				false: {
+					"linux/amd64",
+					"linux/arm",
+					"linux/arm/v4",
+					"linux/arm/v5",
+					"linux/arm/v6",
+					"linux/arm/v7",
+					"linux/arm/v8",
+					"linux/arm/v9",
+					"linux/arm64/v9",
+					"windows/amd64",
+					"windows/arm",
+				},
+			},
+		},
+	} {
+		testcase := tc
+		t.Run(testcase.platform, func(t *testing.T) {
+			p, err := Parse(testcase.platform)
+			if err != nil {
+				t.Fatal(err)
+			}
+			m := Only(p)
+			for shouldMatch, platforms := range testcase.matches {
+				for _, matchPlatform := range platforms {
+					mp, err := Parse(matchPlatform)
+					if err != nil {
+						t.Fatal(err)
+					}
+					if match := m.Match(mp); shouldMatch != match {
+						t.Errorf("Only(%q).Match(%q) should return %v, but returns %v", testcase.platform, matchPlatform, shouldMatch, match)
+					}
+				}
+			}
+		})
+	}
+}