Basics of writing tests using PHPUnit

We're not going to go into very much detail about how to use PHPUnit, and instead leave it to its in-depth documentation ( https://phpunit.de/manual/5.6/en/index.html ). For the purpose of this chapter, we should, however, have a quick look at some of the basics we're going to use for the purposes of testing RxPHP code.

There are some basic rules we should follow:

• All tests for a single class, MyClass, go into a class called MyClassTest, which should inherit from PHPUnit\Framework\TestCase.

• Each test scenario is represented by a function prefixed with test or annotated with @test annotation. This way it can be auto-discovered by PHPUnit.

• Each test function consists of one or more assertions using assert* methods (more on them later). If any one of them fails, the whole test scenario (one test function) is marked as failed. All assertions are inherited from PHPUnit\Framework\TestCase.

• We can specify dependencies between test scenarios using @depends testname...