chore(test): simulation unit tests

[alex-miao]

[Closes/Fixes] #298

Proposed Changes

• Refactor parts of simulation.rs, tracer.rs, and provider_like.rs to be mockable
• Add a few basic unit tests to simulation.rs

[dphilipson]

Looks great! A few notes inline, but these are really good tests.

[dphilipson]

You might consider writing this using the json! macro, which would let you parse the json at compile time, although it doesn't really matter (docs).

[dphilipson]

(Nit) Needs a more descriptive name. trace might be good.

[dphilipson]

Note that you have the option of writing each of these as

"0x5ff137d4b0fdcd49dca30c7cf57e578a026d2789".parse().unwrap()

although writing it with Address::from_str is fine too if you like the clarity.

You also have the option of declaring the test return type as a result:

async fn test_simulate_validation() -> anyhow::Result<()> {

and then you could use ? instead of .unwrap() throughout, but that's just personal preference.

[dphilipson]

Since it's already written it might not be worth it, but there's enough of these that if you had to do this again I would consider writing some kind of helper function to write these with less boilerplate. Something like

fn address(s: &str) -> Address {
    Address::from_str("0x5ff137d4b0fdcd49dca30c7cf57e578a026d2789").unwrap()
}

and then you could have

accessed_contract_addresses: vec![
    address("0x5ff137d4b0fdcd49dca30c7cf57e578a026d2789"),
    address("0xb856dbd4fa1a79a46d426f537455e7d3e79ab7c4"),
    address("0x8abb13360b87be5eeb1b98647a016add927a136c"),
],