They didn't want a mock because it might behave differently: > or to replace it with a mock, which only behaves like Redis until your code relies on something

They didn't want a mock because it might behave differently: > or to replace it with a mock, which only behaves like Redis until your code relies on something the mock implements differently. But, then, what they built did apparently behave differently: > To guard against that, we test the Rust server against the implementation we ported from. > Running the reference suite this way surfaced differences that would be easy to miss otherwise.