expectErr := (err != nil)

		if expectErr != testCase.expectErr {
			t.Fatalf("case %v: error: expected: %v, got: %v, err: %v", i+1, expectErr, testCase.expectErr, err)
		}
	}
}

func testStorageAPIListDir(t *testing.T, storage StorageAPI) {
	err := storage.AppendFile(context.Background(), "foo", "path/to/myobject", []byte("foo"))
	if err != nil {
		t.Fatalf("unexpected error %v", err)
	}

	testCases := []struct {