eslint-mocha-no-only

This package contains an ESLint rule which throws an error (or warning) when the only() method is called on describe, context, it, specify, suite and test Mocha test keywords.

Why do I need this?

only() is a useful Mocha feature that lets the test runner run one specific part of a test suite. Often, developers may end up forgetting to remove the only() method before commiting and pushing their code. This results in the CI tool running only one specific test in the suite which may end up in a false-positive build.

By having ESLint throw an error in such cases, you can rest assured your CI tool runs all your test suites.

Installation

You'll first need to install ESLint:

$ npm i eslint --save-dev

Next, install eslint-plugin-mocha-no-only:

$ npm install eslint-plugin-mocha-no-only --save-dev

Note: If you installed ESLint globally (using the -g flag) then you must also install eslint-plugin-mocha-no-only globally.

Usage

Enable the eslint-plugin-mocha-no-only plugin and rules in your eslint.config.js file.

1import globals from "globals";
2import pluginJs from "@eslint/js";
3import mochaNoOnly from "eslint-plugin-mocha-no-only"
4
5
6export default [
7  {
8    languageOptions: { globals: globals.browser },
9    plugins: { mochaNoOnly },
10    rules: { "mochaNoOnly/mocha-no-only": ["error"] }
11  },
12  pluginJs.configs.recommended,
13];
14

Note: You may want to only enable this rule for files in your tests suite. This can be done by adding an additional config object with a files key.

1import globals from "globals";
2import pluginJs from "@eslint/js";
3import mochaNoOnly from "eslint-plugin-mocha-no-only"
4
5
6export default [
7  {
8    languageOptions: { globals: globals.browser },
9    plugins: { ... },
10    rules: { ... }
11  },
12  {
13    files: ["test/**.js"],
14    plugins: { mochaNoOnly },
15    rules: { "mochaNoOnly/mocha-no-only": ["error"] }
16  },
17  pluginJs.configs.recommended,
18];
19

Examples

Failing

1describe("foobar", function() {
2  var foo;
3  beforeEach(function() {
4    foo = new Foo();
5  });
6
7  it.only("should do things", function() {
8    expect(foo).to.do.things;
9  });
10});

Passing

1describe("foobar", function() {
2  var foo;
3  beforeEach(function() {
4    foo = new Foo();
5  });
6
7  it("should do things", function() {
8    expect(foo).to.do.things;
9  });
10});