Trait mimicry::CallReal

source · 
pub trait CallReal {
    fn call_real(&self) -> RealCallGuard<'_, Self> { ... }
    fn call_real_once(&self) -> RealCallGuard<'_, Self> { ... }
}
Expand description

Controls delegation to real impls. The provided call_* methods in this trait can be used for partial mocking and spying.

This trait can be derived using the corresponding macro; it’s not intended for manual implementation. The trait is also implemented for the Mut and MockRef wrappers.

Call guard checks

RealCallGuards returned by Self::call_real() and Self::call_real_once() must not overlap in terms of their lifetime; otherwise, confusion would arise as to which calls exactly should be delegated to real implementations. This is checked in runtime when creating a guard.

ⓘ
#[mock(using = "MyMock")]
fn answer() -> u32 { 42 }

#[derive(Default, Mock, CallReal)]
struct MyMock {
    // mock state...
    _switch: RealCallSwitch,
}

impl MyMock {
    fn answer(&self) -> u32 {
        let _guard = self.call_real();
        let real_answer = self.call_real_once().scope(answer);
        // ^ will panic here: there is an alive call switch guard
        real_answer + 1
    }
}

let _guard = MyMock::default().set_as_mock();
answer(); // triggers the panic

Provided Methods

Delegates all calls to the mocked functions / methods to the real implementation until the returned RealCallGuard is dropped.

Panics

Panics if the real / mock implementation switch is already set to “real” (e.g., there is an alive guard produced by an earlier call to Self::call_real()). This may lead to unexpected switch value for the further calls and is thus prohibited.

Delegates the first call to the mocked functions / methods to the real implementation until the returned RealCallGuard is dropped. Further calls will be directed to the mock.

Panics

Panics under the same circumstances as Self::call_real().

Implementors