Result Comment Assertion

The result comment assertion uses // => at the end of a line to verify the value of the expression on that line.

Syntax

$x = 42; // => 42
$flag = true; // => true
$nothing = null; // => NULL

How It Works

1. The expression on the left side of // => is evaluated
2. The result is converted to a string using var_export()
3. The var_export output is compared against the expected value on the right

Since var_export is used, the expected values follow PHP's var_export format:

PHP Value	var_export Output	Expected
42	42	42
3.14	3.14	3.14
true	true	true
false	false	false
null	NULL	NULL
'hello'	'hello'	'hello'
[1, 2]	array (0 => 1, 1 => 2,)	array (...)

When to Use

• When documenting APIs where return values matter
• For inline demonstrations of expressions and their results
• When you want a compact, readable assertion format

Examples

Arithmetic

$a = 10 + 5; // => 15
$b = 10 * 3; // => 30

String functions

$upper = strtoupper('hello'); // => 'HELLO'
$len = strlen('test'); // => 4

Boolean checks

$empty = empty([]); // => true
$isset = isset($undefined); // => false

Regular Comments

Regular PHP comments (without =>) are left untouched. Only the // => pattern triggers an assertion:

```php
$x = 42; // This is just a comment, not an assertion
$y = 42; // => 42   <-- This IS an assertion
```