Rely Introduction

Rely is a Jest-inspired native Reason testing framework.

We took the things we loved about Jest (beautiful output, descriptive assertion framework, and snapshot testing), added some type safety, and built a library that can compile and run entire test suites both natively and in JS with Js_of_ocaml in milliseconds.

describe("Example", ({test}) => {
  test("ints", ({expect}) =>
    expect.int(1 + 1).toBe(3)
  );
  test("bools", ({expect}) =>
    expect.bool(true).not.toBe(false)
  );
});

Running 1 test suite

 FAIL  Example
  • Example › ints

    expect.int(received).toBe(expected)

    Expected: 3
    Received: 2

       3 ┆ 
       4 ┆ describe("Example", ({test}) => {
       5 ┆   test("ints", ({expect}) => {
       6 ┆     expect.int(1 + 1).toBe(3);
       7 ┆     ();
       8 ┆   });
       9 ┆   test("bools", ({expect}) => {

      Raised by primitive operation at ./tests/ExampleTest.re:6:4
      Called from ./map.ml:291:20
      Called from ./common/CommonCollections.re:171:8


Test Suites: 1 failed, 0 passed, 1 total
Tests:       1 failed, 1 passed, 2 total
Time:        0.002s