micro-should

Micro testing framework with familiar syntax, multi-env ESM support & parallel execution.

Used in noble cryptography and many other packages.

Usage

npm install micro-should

jsr add jsr:@paulmillr/micro-should

Basic methods:

• should(title, case) or it(title, case) syntax to register a test function
• should.run() or it.run() must always be executed in the end

ENV variables:

• MSHOULD_FAST=1 enables parallel execution in node.js and Bun. Values >1 will set worker count.
• MSHOULD_QUIET=1 enables "quiet" dot reporter

Additional methods:

• describe(prefix, cases) for nested execution
• beforeEacn(fn) to execute code before a function in describe block
• afterEach to execute code after a function in describe block
• should.only(title, case) allows to limit tests to only one case
• should.skip(title, case) allows to skip functions instead of commenting them out
• describe.skip(prefix, cases) to skip describe()-s
• should.runWhen(import.meta.url) helper ensures CLI tests are not run twice if you're using many test files
  • Executes .run() when passed argument is equal to CLI-passed file name. Consider a project with 3 test files: a.test.js, b.test.js, all.js. all.js imports a.test.js and b.test.js. User runs node a.test.js; then node all.js;
  • Writing it.run() everywhere would fail, because it would try to run same tests twice.
  • However, it.runWhen(import.meta.url) would succeed, because it detects whether current file is launched from CLI and not imported.

Basic

To run the example in parallel / quiet setting, save it as a.test.js:

MSHOULD_FAST=1 MSHOULD_QUIET=1 node a.test.js

import { should } from 'micro-should';
import * as assert from 'node:assert'; // examples with node:assert
// you can use any assertion library, e.g. Chai or Expect.js

should('add two numbers together', () => {
  assert.equal(2 + 2, 4);
});

should('catch errors', () => {
  assert.throws(() => {
    throw new Error('invalid');
  });
});

should('produce correct promise result', async () => {
  const fs = await import('node:fs/promises');
  const data = await fs.readFile('README.md', 'utf-8');
  assert.ok(data.includes('Minimal testing'));
});
should.run();

Nested

describe('during any time of day', () => {
  describe('without hesitation', () => {
    should('multiply two numbers together', () => {
      assert.equal(2 * 2, 4);
    });

    should.skip("disable one test by using skip", () => {
      assert.ok(false); // would not execute
    });

    // should.only("execute only one test", () => {
    //   assert.ok(true);
    // });
  });
});

should.run();

Auto-run with cli, do not run when imported

// a.test.js
import { should } from 'micro-should';
should('2 + 2', () => {
  if (2 + 2 !== 4) throw new Error('invalid');
});
should.runWhen(import.meta.url);

// b.test.js
import * from './a.test.js';
should.runWhen(import.meta.url);

Options

Options which can be set via command line, as environment variables:

• MSHOULD_FAST=1 enables parallel execution in node.js and Bun. Values >1 will set worker count.
• MSHOULD_QUIET=1 enables "quiet" dot reporter

Options which can be set via code:

import { should } from 'micro-should';
should.opts.STOP_AT_ERROR = false; // default=true
should.opts.MSHOULD_QUIET = true; // same as env var

License

MIT (c) Paul Miller (https://paulmillr.com), see LICENSE file.