Instruments code for collecting data coverage (instead of code coverage)
Really experimental, do not use yet!
This module can instrument and collect data coverage for functions. Instead of measuring which code lines were executed by the unit tests, it collects the arguments to each function.
Imagine a function checking if a given string is an email address.
function isEmail(s) {
return /^\w+@\w+\.\w{3,4}$/.test(s)
}It looks reasonable and it is simple to test getting 100% code coverage. Something like this would work
it('passes gmail emails', () => {
console.assert(isEmail('user@gmail.com'))
})Yet, the 100% code coverage, collected using a tool like
nyc / istanbul tells us nothing. It is much better
to collect all strings passed to isEmail during all unit tests. In this case, data-cover
reports that we only used a single email!
function isEmail(s) {
/*
s:["user@gmail.com"]
*/
return /^\w+@\w+\.\w{3,4}$/.test(s)
}This makes it very simple to figure out what other classes of inputs should be given by the
unit tests to cover all possible cases: for example emails with 2 letter TLD like user@gmail.ru,
or emails with dots and dashes like user.name@gmail.com.
Typical code coverage collected by nyc
Same unit tests running through data-cover
Install and preload data-cover when running your unit tests, for example when using Mocha
mocha -r data-cover spec.jsStill work in progress
Author: Gleb Bahmutov © 2017
License: MIT - do anything with the code, but don't blame me if it does not work.
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Support: if you find any problems with this module, email / tweet / open issue on Github
Copyright (c) 2017 Gleb Bahmutov
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
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