Struct mimicry::MockGuard

pub struct MockGuard<T: Mock> { /* private fields */ }

Exclusive guard to set the mock state.

A guard can be used to check / adjust the mock state during the test. Dropping the guard also unsets the mock state, so that targeted functions are no longer mocked.

In case of shared mocks, guards also provided synchronization across concurrently executing tests: until a guard is dropped, other threads attempting to call Mock::set_as_mock() will block. Unfortunately, this is not always sufficient to have good results; see Shared docs for discussion.

Examples

#[mock(using = "ValueMock")]
fn answer() -> usize { 42 }

#[derive(Default, Mock)]
struct ValueMock(usize);

impl CheckRealCall for ValueMock {}

impl ValueMock {
    fn answer(&self) -> usize {
        self.0
    }
}

assert_eq!(answer(), 42);
let mut guard: MockGuard<_> = ValueMock::default().set_as_mock();
assert_eq!(answer(), 0);
guard.with(|mock| { mock.0 = 23; });
// ^ updates mock state without releasing the guard
assert_eq!(answer(), 23);

Implementations

impl<T: Mock> MockGuard<T>

pub fn with<R>(&mut self, action: impl FnOnce(&mut T) -> R) -> R

Performs an action on the mock state without releasing the guard. This can be used to adjust the mock state, check or take some parts of it (such as collected args or responses).

pub fn into_inner(self) -> T

Returns the enclosed mock state and releases the exclusive lock.

Trait Implementations

impl<T: Mock> Debug for MockGuard<T>

fn fmt(&self, formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.