expect

An assertions/expectations library for Rust. expect provides a syntax inspired by RSpec and Gomega, and a set of powerful built-in matchers.

Getting expect

expect isn't ready for general use just yet, but you can try it by consuming this Git repository in your Cargo.toml:

[dev-dependencies]
expect = { git = "https://github.com/gcapizzi/expect.git" }

Using expect

The basic structure of an expectation is:

expect(&actual).to(matcher(expected));
expect(&actual).not_to(matcher(expected));

For example:

expect(&(2 + 2)).to(equal(4))

Built-in matchers

Core matchers

• equal:

  expect(&"foo").to(equal("foo"))

String matchers

• match_regex:

  expect(&"abc-123").to(match_regex(r"\d{3}"));

Collection matchers

• contain:

  expect(&[1, 2, 3]).to(contain(2));
  expect(&vec![1, 2, 3]).not_to(contain(4));

• be_empty:

  expect(&Vec::<i32>::new()).to(be_empty());

Option matchers

• be_some:

  expect(&Some("foo")).to(be_some());

• be_none:

  expect(&None::<&str>).to(be_none());

Result matchers

• be_ok:

  expect(&Ok("foo")).to(be_ok());

• be_err:

  expect(&Err("foo")).to(be_err());

Path matchers

• exist:

  expect(&env!("CARGO_HOME")).to(exist());