Jest-Ratchet

Ratchet up code coverage - keep test coverage going only one direction -- up

Jest-Ratchet is a coverage watcher for Jest. Everytime a new level of coverage is reached Jest-Ratchet will automatically update the coverageThreshold.

Installation

npm

npm install jest-ratchet --dev

yarn

yarn add jest-ratchet --dev

Jest Settings

Add jest-ratchet to the reporters section. And also ensure that collectCoverage is enabled and json-summary is added to the coverageReporters.

{
  "collectCoverage": true,
  "coverageReporters": ["json", "lcov", "text", "clover", "json-summary"],
  "reporters": ["default", "jest-ratchet"]
}

Optional Settings

By default, Jest-Ratchet is aggressive with updating coverage thresholds. Every time your coverage ticks up by 0.01%, the coverageThreshold is updated. There are a couple of options dampen this behavior.

• tolerance (number): keeps the threshold below the measured coverage, allowing wiggle room. default: 0 tolerance
• roundDown (boolean): round down to the nearest integer. default: false
• timeout (number): the number of milliseconds to wait for to the Jest coverage json summary. default: wait indefinitely

Here's how to pass configuration to Jest-Ratchet, per the Jest documentation

{
  "collectCoverage": true,
  "coverageReporters": ["json", "lcov", "text", "clover", "json-summary"],
  "reporters": [
    "default",
    [
      "jest-ratchet",
      { "tolerance": 2, "roundDown": true, "timeout": 5000 }
    ]
  ]
}