tiny-esm-test-runner

Small test runner for ES modules style modules on Node.js. This is for you ES modules addict, if you hope to write tests for ES modules as ES modules strictly.

Benefits

A testcase written for this testing framework are completely valid ES module. Thus you don't need to put any ugly exceptions for eslint about your testcases, and it will allow you to keep testcases more strict easily.

How to create test cases

First, please create test files as module files. For example:

// Save as "test-example.js"
 
import { assert } from 'tiny-esm-test-runner';
const { is, isNot, ok, ng } = assert;
 
// Function (both sync and async) exported with the name "setUp" is
// automatically detected as the common setup for each test.
// This is optional.
export function setUp() {
  // common setup process
}
 
// Function (both sync and async) exported with the name "tearDown" is
// automatically detected as the common teardown for each test.
// This is optional.
export function tearDown() {
  // common teardown process
}
 
// Function (both sync and async) exported with the name "shutDown" is
// automatically detected as the finalization process for all tests.
// This is optional.
export function shutDown() {
  // the finalization process
}
 
// All functions (both sync and async) exported with a name starting
// with the prefix "test" are automatically detected as tests.
export function testSuccess() {
  const expected = 'AAA';
  const actual = 'aaa'.toUpperCase();
  is(expected, actual);
}
 
export function testFail() {
  const expected = 'AAA';
  const actual = 'aaa'.toLowerCase();
  is(expected, actual);
}

After that run the run-tiny-esm-test-runner command with created testcase files, like:

$ run-tiny-esm-test-runner test-*.js

The command returns 0 if all tests succeeded. Otherwise 1 will be returned and details are printed.

For your modules

If you develop a npm module, you'll put the test script like:

{
  "scripts": {
    ...
    "test": "run-tiny-esm-test-runner test/test-*.js"
  },
  "devDependencies": {
    ...
    "tiny-esm-test-runner": "^1.1.0"
  }
}

After that, you just run npm install && npm test to do tests.

Available assertions

is(expected, actual, message)

This assertion accepts two or three arguments:

• expected (required, any type): The expected value.
• actual (required, any type): The actual value.
• message (optional, string): An extra message printed when the assertion failed.

This succeeds when the actual value equals to the given expected value, based on the === operator. Even if they are not exact same, they are re-compared again as JSON strings if they are JSON-stringifiable objects (Object, Array, and so on).

isNot(expected, actual, message)

This assertion accepts two or three arguments:

• expected (required, any type): The expected value.
• actual (required, any type): The actual value.
• message (optional, string): An extra message printed when the assertion failed.

This is opposite of is(), succeeds when the actual value does not equal to the given expected value, based on the !== operator. They are also re-compared again as JSON strings if they are JSON-stringifiable objects (Object, Array, and so on).

ok(actual, message)

This assertion accepts one or two arguments:

• actual (required, any type): The actual value.
• message (optional, string): An extra message printed when the assertion failed.

This succeeds when the actual value is detected as true on JavaScript.

ng(actual, message)

This assertion accepts one or two arguments:

• actual (required, any type): The actual value.
• message (optional, string): An extra message printed when the assertion failed.

This is opposite of ok(), succeeds when the actual value is detected as false on JavaScript.

Data driven tests

If you set a parameters property to a test function, it will become a data-driven test. For example:

testUpperCase.parameters = [
  ['AAA', 'aaa'],
  ['BBB', 'bbb']
];
export function testUpperCase([expected, data]) {
  is(expected, data.toUpperCase());
}

or

testUpperCase.parameters = {
  a: ['AAA', 'aaa'],
  b: ['BBB', 'bbb']
};
export function testUpperCase([expected, data]) {
  is(expected, data.toUpperCase());
}

The parameters property must be an Array or an Object. If you specify an Array, the test function will be called multiple times for each element. If you specify an Object, the test function will be called multiple times with values for each key.

Given parameters are available on setUp() and tearDown() also.

For debugging

If you set runnable property to test functions with any true compatible value, only such flagged tests are executed and other tests are skipped. This will help you to run only some failed tests again and again on debugging. For example:

// This test is skipped.
export function testSuccess() {
  const expected = 'AAA';
  const actual = 'aaa'.toUpperCase();
  is(expected, actual);
}
 
// This test is executed.
testFail.runnable = true;
export function testFail() {
  const expected = 'AAA';
  const actual = 'aaa'.toLowerCase();
  is(expected, actual);
}

Example usecases

• self test
• https://github.com/piroor/webextensions-lib-dom-updater/tree/master/test
• https://github.com/piroor/copy-selected-tabs-to-clipboard/tree/master/test
• https://github.com/piroor/xulmigemo/tree/master/webextensions/test

License

MIT