test: add basic integration tests

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/containerd/continuity/fs/fstest/compare.go

@@ -0,0 +1,68 @@
+/*
+   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 fstest
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/containerd/continuity"
+)
+
+// CheckDirectoryEqual compares two directory paths to make sure that
+// the content of the directories is the same.
+func CheckDirectoryEqual(d1, d2 string) error {
+	c1, err := continuity.NewContext(d1)
+	if err != nil {
+		return fmt.Errorf("failed to build context: %w", err)
+	}
+
+	c2, err := continuity.NewContext(d2)
+	if err != nil {
+		return fmt.Errorf("failed to build context: %w", err)
+	}
+
+	m1, err := continuity.BuildManifest(c1)
+	if err != nil {
+		return fmt.Errorf("failed to build manifest: %w", err)
+	}
+
+	m2, err := continuity.BuildManifest(c2)
+	if err != nil {
+		return fmt.Errorf("failed to build manifest: %w", err)
+	}
+
+	diff := diffResourceList(m1.Resources, m2.Resources)
+	if diff.HasDiff() {
+		return fmt.Errorf("directory diff between %s and %s\n%s", d1, d2, diff.String())
+	}
+
+	return nil
+}
+
+// CheckDirectoryEqualWithApplier compares directory against applier
+func CheckDirectoryEqualWithApplier(root string, a Applier) error {
+	applied, err := os.MkdirTemp("", "fstest")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(applied)
+	if err := a.Apply(applied); err != nil {
+		return err
+	}
+	return CheckDirectoryEqual(applied, root)
+}