WireTests / WireTest

For auto-discovery, create ClassName.test.php in the same directory as the class being tested. Define a class named WireTest_ClassName that extends WireTest:

<?php namespace ProcessWire;

class WireTest_MyClass extends WireTest {

    public function init() {
        // Optional: setup before execute()
    }

    public function execute() {
        $obj = new MyClass();
        $this->check('greet() returns expected string', 'hello', $obj->greet());
        $this->check('count() is positive', true, $obj->count() > 0);
    }

    public function finish() {
        // Optional: cleanup; runs even if execute() throws
    }
}

// Strict equality (default operator is ===)
$this->check('test name', $expected, $actual);

// Specify an operator
$this->check('test name', $expected, $actual, $operator);

Supported operators:

On failure, check() throws WireTestException with a message showing expected vs. actual.

$this->check('value is hello', 'hello', $result);             // ===
$this->check('output contains keyword', 'error', $log, '*='); // contains
$this->check('count is positive', 0, $count, '<');            // 0 < $count

$this->ok('message');    // Output an OK status line
$this->fail('reason');   // Fail the test (throws WireTestException)
$this->li('message');    // Output a plain status line (no pass/fail implied)

$page = $this->getTestPage();                        // Shared /wire-test/ page
$fresh = $this->wire()->pages->getFresh($page->id);  // Reload page from database
$page->of(false);                                    // Turn off output formatting before saving

Tests that store and retrieve field values should use getTestPage(), create the field in init(), and restore any modified field settings in finish():

<?php namespace ProcessWire;

class WireTest_FieldtypeMyModule extends WireTest {

    protected $name = 'wire_test_myfield';

    public function init() {
        $page    = $this->getTestPage();
        $fields  = $this->wire()->fields;
        $field   = $fields->get($this->name);
        if(!$field) {
            $field = $fields->new('FieldtypeMyModule', $this->name, 'My Field');
            $this->ok("Created field: $this->name");
        }
        $fieldgroup = $page->template->fieldgroup;
        if(!$fieldgroup->hasField($field)) {
            $fieldgroup->add($field);
            $fieldgroup->save();
        }
    }

    public function execute() {
        $page  = $this->getTestPage();
        $pages = $this->wire()->pages;
        $name  = $this->name;

        $page->of(false);
        $page->set($name, 'test value');
        $page->save($name);

        $fresh = $pages->getFresh($page->id);
        $this->check('value round-trip', 'test value', $fresh->get($name));

        $match = $pages->findOne("template=wire-test, $name='test value'");
        $this->check('selector finds test page', $page->id, $match->id);
    }
}

• Test files are auto-discovered in wire/core/, wire/modules/, and site/. Matching ClassName.test.php or WireTest_ClassName.php files are found automatically when they contain a WireTest_ClassName class.
• Direct file paths may point to any file that defines a WireTest_* class; directory paths are searched recursively, subject to WireTests' built-in exclusions.
• If multiple tests have the same name, run the desired test by path rather than name.
• Tests for uninstalled modules are skipped automatically unless the target class exists as a core/PHP class (for example, Sanitizer).
• Field names in Fieldtype tests should use WireTests::fieldPrefix (wire_test_) to avoid collisions.
• Make tests idempotent: guard field/option creation so it's safe to run more than once.
• finish() is always called, even when execute() throws — use it for cleanup.
• Append --json to any run for machine-readable output suitable for CI pipelines.
• For comprehensive guide on installation, discovery, best practices, and examples, see the README.
• Source files: wire/modules/System/WireTests/WireTests.module.php, wire/modules/System/WireTests/WireTest.php