Output Assertion

The Output assertion verifies the exact output of a code block.

Syntax

```php
echo 'Hello, World!';
```
<!-- doctest: Hello, World! -->

How It Works

1. The code block executes in an isolated process
2. All output (echo, print, etc.) is captured via ob_start() / ob_get_clean()
3. The captured output is compared against the expected value
4. Output is normalized: trailing whitespace is trimmed, line endings are unified

Multi-line Output

The HTML comment form supports multi-line expected output:

```php
echo "line 1\nline 2\nline 3";
```
<!-- doctest: line 1
line 2
line 3 -->

Wildcards

Use wildcards for dynamic portions of the output:

```php
echo 'Processed 42 items at ' . date('Y-m-d');
```
<!-- doctest: Processed {{int}} items at {{date}} -->

Examples

echo 'Hello, World!';

echo "The answer is " . (6 * 7);

Tips

• Output comparison is exact (after normalization). Use OutputContains for partial matches.
• Use {{...}} wildcard to match arbitrary content in the middle of output.
• The HTML comment form avoids conflicts with PHP syntax.