Demonstrate Mocha not running `beforeEach` hooks on outer contexts when using grep.

README.md

Running lifecycle hooks with a mocha grep

given the following mocha code:

describe("the outer context", function () {
  beforeEach(function() {
    this.didRunBeforeEach = true;
  });
  describe("the inner context", function() {
    it("runs its parent beforeEach", function() {
      expect(this.didRunBeforeEach).to.equal(true);
    });
  }) ;
});

because "the inner context" is nested inside "the outer context", it should run the outer context's beforeEach hook. It does do this under normal circumstances:

~/C/E/mocha-demo ❯❯❯ npm t

> mocha-demo@1.0.0 test /Users/cowboyd/Code/Ember/mocha-demo
> mocha index.js



  the outer context
    the inner context
      ✓ runs its parent beforeEach


  1 passing (7ms)

But if we configure the inner context to use it.only to select only the single test-case:

describe("the outer context", function () {
  beforeEach(function() {
    this.didRunBeforeEach = true;
  });
  describe("the inner context", function() {
    it.only("runs its parent beforeEach", function() {
      expect(this.didRunBeforeEach).to.equal(true);
    });
  }) ;
});

Then it fails with the following error:

~/C/E/mocha-demo ❯❯❯ npm t                                                                                                                                                                                                                  ⏎

> [email protected] test /Users/cowboyd/Code/Ember/mocha-demo
> mocha index.js


  1) runs its parent beforeEach

  0 passing (9ms)
  1 failing

  1)  runs its parent beforeEach:
     AssertionError: expected undefined to equal true
      at Context.<anonymous> (index.js:15:40)



npm ERR! Test failed.  See above for more details.

Which indicates that the hook is either not being run.

index.js

/*global require */

var mocha = require('mocha'),
    expect = require('chai').expect,
    describe = mocha.describe,
    it = mocha.it,
    beforeEach = mocha.beforeEach;

describe("the outer context", function () {
  beforeEach(function() {
    this.didRunBeforeEach = true;
  });
  describe("the inner context", function() {
    it.only("runs its parent beforeEach", function() {
      expect(this.didRunBeforeEach).to.equal(true);
    });
  }) ;
});

package.json

{
  "name": "mocha-demo",
  "version": "1.0.0",
  "description": "Demonstrate strange behavior in mocha",
  "main": "index.js",
  "scripts": {
    "test": "mocha index.js"
  },
  "author": "",
  "license": "MIT",
  "devDependencies": {
    "chai": "^3.4.1",
    "mocha": "^2.3.3"
  }
}