title: Correctness rules outline: [2, 3]

Correctness rules

This document details the rules available in the Correctness category.

assert-description

Detects assert functions that do not have a description.

Assert functions should have a description to make it easier to understand the purpose of the assertion.

Configuration

Examples

Correct code

<?php

assert($user->isActivated(), 'User MUST be activated at this point.');

Incorrect code

<?php

assert($user->isActivated());

identity-comparison

Detects equality and inequality comparisons that should use identity comparison operators.

Configuration

Examples

Correct code

<?php

if ($a === $b) {
    echo '$a is same as $b';
}

Incorrect code

<?php

if ($a == $b) {
    echo '$a is same as $b';
}

ineffective-format-ignore-next

Detects [@mago-format-ignore-next](https://github.com/mago-format-ignore-next) markers that will have no effect.

The formatter's ignore-next marker works at the statement level. When a marker is placed inside an expression (like function call arguments, array elements, or other non-statement contexts), it will not affect the formatter's output.

To effectively ignore the next statement, place the marker immediately before a complete statement at the top level of a block or file.

Configuration

Examples

Correct code

<?php

// This works - marker is before a statement
// [@mago-format-ignore-next](https://github.com/mago-format-ignore-next)
const GRID = [
  [1, 2, 3], [1, 2, ], [0,    0],
];

foo();

Incorrect code

<?php

// This doesn't work - marker is inside an array literal
$arr = [ // [@mago-format-ignore-next](https://github.com/mago-format-ignore-next)
    1,
    2,
];

ineffective-format-ignore-region

Detects [@mago-format-ignore-start](https://github.com/mago-format-ignore-start) markers that will have no effect.

The formatter's ignore regions work at the statement level. When an ignore marker is placed inside an expression (like function call arguments, array elements, or other non-statement contexts), it will not affect the formatter's output.

To effectively ignore a region, place the ignore markers between complete statements at the top level of a block or file.

Configuration

Examples

Correct code

<?php

// This works - markers are between statements
// [@mago-format-ignore-start](https://github.com/mago-format-ignore-start)
$x = 1;  $y = 2;  // preserved as-is
// [@mago-format-ignore-end](https://github.com/mago-format-ignore-end)

foo();

Incorrect code

<?php

// This doesn't work - markers are inside a function call
foo( // [@mago-format-ignore-start](https://github.com/mago-format-ignore-start)
    $x,
    $y
// [@mago-format-ignore-end](https://github.com/mago-format-ignore-end)
);

invalid-open-tag

Detects misspelled PHP opening tags like <php? instead of <?php.

A misspelled opening tag will cause the PHP interpreter to treat the following code as plain text, leading to the code being output directly to the browser instead of being executed. This can cause unexpected behavior and potential security vulnerabilities.

Configuration

Examples

Correct code

<?php

echo 'Hello, world!';

Incorrect code

<php?

echo 'Hello, world!';

no-assign-in-argument

Detects assignments in function call arguments which can lead to unexpected behavior and make the code harder to read and understand.

Configuration

Examples

Correct code

<?php

$x = 5;
foo($x);

Incorrect code

<?php

foo($x = 5);

no-assign-in-condition

Detects assignments in conditions which can lead to unexpected behavior and make the code harder to read and understand.

Configuration

Examples

Correct code

<?php

$x = 1;
if ($x == 1) {
    // ...
}

Incorrect code

<?php

if ($x = 1) {
    // ...
}

no-empty-catch-clause

Warns when a catch clause is empty.

An empty catch clause suppresses exceptions without handling or logging them, potentially hiding errors that should be addressed. This practice, known as "exception swallowing," can make debugging significantly more difficult.

Configuration

Examples

Correct code

<?php

try {
    // some code that might throw an exception
} catch(Exception $e) {
    // Handle the error, log it, or re-throw it.
    error_log($e->getMessage());
}

Incorrect code

<?php

try {
    // some code
} catch(Exception $e) {
    // This block is empty and swallows the exception.
}

no-only

Detects usage of ->only() in Pest tests which should not be committed.

The ->only() modifier causes only that specific test to run, which can lead to incomplete test coverage if accidentally committed to the repository.

Requirements

• Integration: Pest

Configuration

Examples

Correct code

<?php

test('example test', function () {
    expect(true)->toBeTrue();
});

it('does something', function () {
    expect(1)->toBe(1);
});

Incorrect code

<?php

test('example test', function () {
    expect(true)->toBeTrue();
})->only();

it('does something', function () {
    expect(1)->toBe(1);
})->only();

strict-assertions

Detects non-strict assertions in test methods. Assertions should use strict comparison methods, such as assertSame or assertNotSame instead of assertEquals or assertNotEquals.

Requirements

• Integration: PHPUnit

Configuration

Examples

Correct code

<?php

declare(strict_types=1);

use PHPUnit\Framework\TestCase;

final class SomeTest extends TestCase
{
    public function testSomething(): void
    {
        $this->assertSame(42, 42);
    }
}

Incorrect code

<?php

declare(strict_types=1);

use PHPUnit\Framework\TestCase;

final class SomeTest extends TestCase
{
    public function testSomething(): void
    {
        $this->assertEquals(42, 42);
    }
}

strict-behavior

Detects functions relying on loose comparison unless the $strict parameter is specified. The use of loose comparison for these functions may lead to hard-to-debug, unexpected behaviors.

Requirements

• PHP version: >= 7.0.0

Configuration

Examples

Correct code

<?php

in_array(1, ['foo', 'bar', 'baz'], strict: true);

Incorrect code

<?php

in_array(1, ['foo', 'bar', 'baz']);

strict-types

Detects missing declare(strict_types=1); statement at the beginning of the file.

Requirements

• PHP version: >= 7.0.0

Configuration

Examples

Correct code

<?php

declare(strict_types=1);

echo "Hello, World!";

Incorrect code

<?php

echo "Hello, World!";

switch-continue-to-break

Detects the use of continue inside a switch statement, which should be break instead.

In PHP, continue inside a switch behaves the same as break, but using continue is misleading because it suggests continuing a loop.

Configuration

Examples

Correct code

<?php

switch ($value) {
    case 1:
        echo 'one';
        break;
}

Incorrect code

<?php

switch ($value) {
    case 1:
        echo 'one';
        continue;
}

use-specific-assertions

Suggests using specific PHPUnit assertions instead of generic equality assertions when comparing with null, true, or false.

Using specific assertions like assertNull, assertTrue, and assertFalse provides clearer error messages and makes test intent more explicit.

Requirements

• Integration: PHPUnit

Configuration

Examples

Correct code

<?php

declare(strict_types=1);

use PHPUnit\Framework\TestCase;

final class SomeTest extends TestCase
{
    public function testSomething(): void
    {
        $this->assertNull($value);
        $this->assertTrue($flag);
        $this->assertFalse($condition);
    }
}

Incorrect code

<?php

declare(strict_types=1);

use PHPUnit\Framework\TestCase;

final class SomeTest extends TestCase
{
    public function testSomething(): void
    {
        $this->assertEquals(null, $value);
        $this->assertSame(true, $flag);
        $this->assertEquals(false, $condition);
    }
}