You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: op_test.go
    path of file: ./repos/jackal/pkg/storage/cached
    
    the code of the file until where you have to start completion: // Copyright 2022 The jackal Authors
//
// Licensed under the Apache License, Ver
    
func TestCachedRepository_UpdateOp(t *testing.T) {
	// given
	var output string

	cacheMock := &cacheMock{}
	cacheMock.DelFunc = func(ctx context.Context, ns string, keys ...string) error {
		output += "del"
		return nil
	}
	updateFn := func(context.Context) error {
		output += ":rep_update"
		return nil
	}

	// when
	op := updateOp{c: cacheMock, invalidateKeys: []string{"k0"}, updateFn: updateFn}
	_ = op.do(context.Background())

	// then
	require.Equal(t, "del:rep_update", output) // ensure proper order
}