Money VS Infection

moneyphp: PHP implementation of Fowler's Money pattern

There's also https://github.com/moneyphp/money, which is great.

Or you can use MoneyPHP, which uses BCMath, and it takes care of all of your problems.

Instead, you want to use a Money object of some sort instead; e.g. https://github.com/moneyphp/money.

Yeah I usually use moneyphp for this

https://github.com/moneyphp/money to handle money

With that in place, let's talk about our test project for a minute. We are going to build a small library on top of Money, a popular PHP package facilitating the manipulation of monetary values and currencies.

In addition to the essential advice above to use Integers of the lowest denomination to store prices, you can also look into using a library to help with all the money math, conversions, comparisons etc https://github.com/moneyphp/money

Read the readme from moneyphp: https://github.com/moneyphp/money

consider adding mutation tests

Obviously, we can not generate mutants manually. For that purpose, there are mutation testing utilities. For PHP, we have Infection.

Infection: PHP Mutation Testing library. Plugins: roave/infection-static-analysis-plugin: Static analysis on top of mutation testing - prevents escaped mutants from being invalid according to static analysis bitexpert/captainhook-infection: Captain Hook Plugin to run InfectionPHP only against the changed files of a commit

Infection: PHP Mutation Testing library. Plugins: roave/infection-static-analysis-plugin: Static analysis on top of mutation testing - prevents escaped mutants from being invalid according to static analysis bitexpert/captainhook-infection: Captain Hook Plugin to run InfectionPHP only against the changed files of a commit

If you want to enforce testing automatically probably the best option is to rely on mutation testing, using Infection. That doesn't just check that the tests cover the code, it checks that if the code was different to what it is then the tests would (usually) fail.

IMO code coverage is a very flawed metric on its own. A high percentage doesn't guarantee that the tests actually test the right things, and it would be much more efficient if mutation testing was used (e.g. Infection). It still uses the generated code coverage reports, but only as a base for its own metrics.

For your last edit - you can also add infection which will infect your code with other values, like if you expect a positive number, it will try and inject a negative number - and see what happens - does your code break everything or something. Also it will try to inject false where you might expect a true and many many other things, and yes you will get some weird results from infection, but its a good thing to look at, and atleast check the logs and see why the infection failed at a test.

The only one that I've used is infection for PHP.

That's practically a light form of mutant testing. Have you checked Infection?