snapshotter: add more assertion

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

fs/fstest/compare.go

@@ -1,6 +1,9 @@
 package fstest
 
 import (
+	"io/ioutil"
+	"os"
+
 	"github.com/pkg/errors"
 	"github.com/stevvooe/continuity"
 )
@@ -35,3 +38,16 @@ func CheckDirectoryEqual(d1, d2 string) error {
 
 	return nil
 }
+
+// CheckDirectoryEqualWithApplier compares directory against applier
+func CheckDirectoryEqualWithApplier(root string, a Applier) error {
+	applied, err := ioutil.TempDir("", "fstest")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(applied)
+	if err := a.Apply(applied); err != nil {
+		return err
+	}
+	return CheckDirectoryEqual(applied, root)
+}

fs/fstest/file.go

@@ -37,8 +37,16 @@ func CreateFile(name string, content []byte, perm os.FileMode) Applier {
 	})
 }
 
-// RemoveFile returns a file applier which removes the provided file name
-func RemoveFile(name string) Applier {
+// Remove returns a file applier which removes the provided file name
+func Remove(name string) Applier {
+	return applyFn(func(root string) error {
+		return os.Remove(filepath.Join(root, name))
+	})
+}
+
+// RemoveAll returns a file applier which removes the provided file name
+// as in os.RemoveAll
+func RemoveAll(name string) Applier {
 	return applyFn(func(root string) error {
 		return os.RemoveAll(filepath.Join(root, name))
 	})