matthauck / mockers

Mocking library for Rust

master	0.5.7

Mockers

Mocking library for Rust.

Inspired by Google Mock library for C++.

User Guide

Limitations

For now it is not a full-featured mocking library, but just a prototype to gather feedback. For example, only methods with four or less arguments are supported, non-'static lifetimes are not supported and so on.

Mocking magic is implemented using compiler plugin on nightly Rust (it was tested to work with 1.15.0-nightly (d5814b03e 2016-11-23)) and code generation on stable Rust. See User Guide for details.

Usage at a glance

This is a very short introduction to show what is possible and how it looks. Read User Guide for details.

We will use nightly Rust in this example for simplicity.

For multirust, run the following command:

$ multirust override nightly

Or if you're using rustup:

$ rustup override set nightly

Cargo.toml:

[dependencies]
mockers_macros = "0.5.7"

[dev-dependencies]
mockers = "0.5.7"

src/lib.rs:

#![feature(plugin, custom_derive)]
#![plugin(mockers_macros)]

#[cfg(test)] extern crate mockers;

#[derive(Mock)]
pub trait AirConditioner {
    fn make_hotter(&mut self, by: i16);
    fn make_cooler(&mut self, by: i16);
    fn get_temperature(&self) -> i16;
}

pub fn set_temperature_20(cond: &mut AirConditioner) {
    let t = cond.get_temperature();
    if t < 20 {
        cond.make_hotter(20 + t);
    } else {
        cond.make_cooler(t - 20);
    }
}

#[cfg(test)]
mod test {
  use super::*;
  use mockers::Scenario;

  #[test]
  fn test_set_temperature_20() {
      let mut scenario = Scenario::new();
      let mut cond = scenario.create_mock_for::<AirConditioner>();

      scenario.expect(cond.get_temperature_call().and_return(16));
      scenario.expect(cond.make_hotter_call(4).and_return(()));

      set_temperature_20(&mut cond);
  }
}

Run tests:

$ cargo test
   Compiling air v0.1.0 (file:///Users/kriomant/Temp/air)
     Running target/debug/air-b2c5f8b6920cb30a

running 1 test
test test::test_set_temperature_20 ... FAILED

failures:

---- test::test_set_temperature_20 stdout ----
	thread 'test::test_set_temperature_20' panicked at '

error: unexpected call to `AirConditioner#0.make_hotter(36)`

note: here are active expectations for AirConditioner#0.make_hotter

  expectation `AirConditioner#0.make_hotter(4)`:
    arg #0: 36 is not equal to 4

'
note: Run with `RUST_BACKTRACE=1` for a backtrace.


failures:
    test::test_set_temperature_20

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured

error: test failed

License

Copyright © 2016 Mikhail Trishchenkov

Distributed under the MIT License.