In previous post we saw how we can define the karma coverage threshold, using the magic check command:

coverageReporter: {
  check: {
    global: {
       statements: 82,
       lines: 67,
       functions: 100,
       branches: 85
    }
  }
}

This way the test run will fail if the code coverage get’s below your threshold.

Note! This way you can also prevernt silly unfortunate mistakes, such as committing the f word (fdescribe or fit)…

Show Must Go On…

Well, life happens, and you continue with your project.
You’ve been a very good boy, and your coverage is now better.
You want to update you’re coverage threshold to the new standard.

Manual Labor?

No.

Threshold Outsourcing

First, save your threshold in a separate file:

coverageReporter: {
  check: {
    global: require('./coverage.conf.json') 
  }
}

Now, your coverage.conf.json will look like this:

{
  "statements": 68,
  "branches": 49,
  "functions": 61,
  "lines": 68
}

Json Coverage Report

It turns out that you also have a json reporter and a json-summary reporter. Unfortunately, it still doesn’t show up in karma-coverage docs yet (I’ve opened a PR).

Try this:

reporters: [
         {type: 'json-summary'}
      ]

You’ll get a beautiful json, with your summary coverage.

Define New Goals

First, let’s get the last run coverage summary:

//read the "coverage-summary.json" file
let fileContent = fs.readFileSync('coverage-summary.json');
//parse string to json
let coverageSummary = JSON.parse(fileContent);

Then, extract the percentage results.

We’de like to add a FLEX factor, to reduce the roughness of the latest coverage results (I’ve set it to 0.5):

//define new thresholdConfig
let thresholdConfig = {};
//threshold factors
let factors = ['lines', 'statements', 'branches', 'functions'];
//extract data from coverageSummary to thresholdConfig
//FLEX is a number to have some flexibility 
factors.forEach(key => 
    thresholdConfig[key] = coverageSummary.total[key].pct - FLEX
    );

Now, you can define you new threshold.

//overwrite the thresholdConfig to "coverage.conf.json"
fs.writeFileSync('coverage.conf.json', 
    JSON.stringify(thresholdConfig), 
    'utf8');

CI/CD

The next stage would be to add a stage to you CI/CD cycle:

• commit
• run test
• update thresholds
• commit “coverage.conf.json” (but don’t rerun tests)