test mocha behavior on errors after timeout

done.js

describe("with done:", function() {
  it("done(error) after timeout", function(done) {
    this.timeout(10)
    setTimeout(function() { done(new Error("GOTCHA!")) }, 100)
  })
  it("this one is safe because error is reported through done", function(done) {
    this.timeout(5000)
    setTimeout(done, 1000)
  })
})

mocha.opts

*.js --slow 10000

package.json

{
  "scripts": {
    "pretest:old": "npm i mocha@2.x",
    "test:old": "npm run test:run",
    "pretest:new": "npm i mocha@3.x",
    "test:new": "npm run test:run",
    "test:run": "mocha --version && mocha --opts mocha.opts",
    "test": "npm run test:old || npm run test:new"
  }
}

promise.js

describe("with promise:", function() {
  it("reject after timeout", function(done) {
    this.timeout(10)
    return new Promise(function(resolve, reject) {
      setTimeout(resolve, 100)
    }).then(function() { throw new Error("GOTCHA!") })
  })
  it("this one is safe because error is reported through promise", function(done) {
    this.timeout(5000)
    setTimeout(done, 1000)
  })
})

throw.js

describe("with throw:", function() {
  it("throw after timeout", function(done) {
    this.timeout(10)
    setTimeout(function() { throw new Error("GOTCHA!") }, 100)
  })
  it("if the other test was not timing out, it would not interfere with this one", function(done) {
    this.timeout(5000)
    setTimeout(done, 1000)
  })
})