Function expect_call 

fn expect_call(
    state: &mut Cheatcodes,
    target: &Address,
    calldata: &Bytes,
    value: Option<&U256>,
    gas: Option<u64>,
    min_gas: Option<u64>,
    count: u64,
    call_type: ExpectedCallType,
) -> Result

Handles expected calls specified by the expectCall cheatcodes.

It can handle calls in two ways:

• If the cheatcode was used with a count argument, it will expect the call to be made exactly count times. e.g. vm.expectCall(address(0xc4f3), abi.encodeWithSelector(0xd34db33f), 4) will expect the call to address(0xc4f3) with selector 0xd34db33f to be made exactly 4 times. If the amount of calls is less or more than 4, the test will fail. Note that the count argument cannot be overwritten with another vm.expectCall. If this is attempted, expectCall will revert.
• If the cheatcode was used without a count argument, it will expect the call to be made at least the amount of times the cheatcode was called. This means that vm.expectCall without a count argument can be called many times, but cannot be called with a count argument after it was called without one. If the latter happens, expectCall will revert. e.g vm.expectCall(address(0xc4f3), abi.encodeWithSelector(0xd34db33f)) will expect the call to address(0xc4f3) and selector 0xd34db33f to be made at least once. If the amount of calls is 0, the test will fail. If the call is made more than once, the test will pass.