Meet Phillip, the newest member of your test team.

Writing Tests

Tests are written using the simple helper test(). It take two arguments, a short description of the test, and a callback to execute. The test object is passed into the callback as the first argument.

test('My First Test', function($t) {
    // Test code goes here

The simplest way to write a test, it to call pass() or fail() directly.

test('Does 1 equal 1', function($t) {
    if (1 === 1) {
        return $t->pass();

    return $t->fail('1 does not equal 1');

The pass() method can also take a boolean argument, to simplify your test even further. If the expression passed to pass() evaluates to true, the test passes, otherwise it will fail.

test('Does this equal that', function($t) {
    return $t->pass('this' === 'that');

There are also error() and skip() methods available on the test object, allowing you to manually determine the test's result.


Assertions can be made by calling the is() or does() methods on the test object, both of which take a single value as an argument. You can chain assertion methods to these to make assertions against this first value. is() and does() are aliases of each other, and both are provided to allow you to write your assertion chains in plain english.

test('Does 1 equal 1', function($t) {
  $t->does(new Object)->implement(IteratorAggregate::class);

The assertions are run in order, and if any of them should fail, the test is stopped immediately and marked as failed.

Here are the assertion methods available to you.


Inverts the assertion. Any assertions appearing after this in the chain will return the opposite result.


Asserts that two values are equal, and of equal type.


Asserts that two values are equivalent, regardless of type.


Asserts the a value is empty.


Asserts that the value is an array.


Asserts that the value is either an array, or implements PHP's Traversable interface.

$t->is(new SplFixedArray(10))->traversable();

Asserts that the value is an instance of a class.

$t->is(new SplFixedArray(10))->anInstanceOf(IteratorAggregate::class);

Asserts that the value implements an interface. This differs from anInstanceOf() in that it will only pass for an implemented interface, and not for a parent class.

$t->does(new SplFixedArray(10))->implement(IteratatorAggregate::class);

Asserts that the value matches a regular expression.