cache: move to backend package

internal/backend/cache/cache_test.go

@@ -0,0 +1,46 @@
+package cache
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/restic/restic/internal/restic"
+	rtest "github.com/restic/restic/internal/test"
+)
+
+func TestNew(t *testing.T) {
+	parent := rtest.TempDir(t)
+	basedir := filepath.Join(parent, "cache")
+	id := restic.NewRandomID().String()
+	tagFile := filepath.Join(basedir, "CACHEDIR.TAG")
+	versionFile := filepath.Join(basedir, id, "version")
+
+	const (
+		stepCreate = iota
+		stepComplete
+		stepRmTag
+		stepRmVersion
+		stepEnd
+	)
+
+	for step := stepCreate; step < stepEnd; step++ {
+		switch step {
+		case stepRmTag:
+			rtest.OK(t, os.Remove(tagFile))
+		case stepRmVersion:
+			rtest.OK(t, os.Remove(versionFile))
+		}
+
+		c, err := New(id, basedir)
+		rtest.OK(t, err)
+		rtest.Equals(t, basedir, c.Base)
+		rtest.Equals(t, step == stepCreate, c.Created)
+
+		for _, name := range []string{tagFile, versionFile} {
+			info, err := os.Lstat(name)
+			rtest.OK(t, err)
+			rtest.Assert(t, info.Mode().IsRegular(), "")
+		}
+	}
+}