OutputJson Assertion

The OutputJson assertion compares JSON output structurally, ignoring key order and whitespace.

Syntax

```php
echo json_encode(['name' => 'DocTest', 'php' => '8.4+']);
```
<!-- doctest-json: {"name": "DocTest", "php": "8.4+"} -->

How It Works

1. The code block executes and its output is captured
2. Both the expected JSON and actual output are decoded with json_decode()
3. Keys are recursively sorted so key order doesn't matter
4. If either side has invalid JSON, the assertion fails with a descriptive error

Key Order Independence

The comparison is structural, so key order doesn't matter:

echo json_encode(['b' => 2, 'a' => 1]);

Both produce the same decoded structure, so this passes.

Nested Structures

Works with nested objects and arrays:

echo json_encode([
    'user' => ['name' => 'Alice', 'age' => 30],
    'roles' => ['admin', 'editor'],
]);

When to Use

• When your code outputs JSON and you want to verify the structure
• When key ordering may vary between PHP versions or configurations
• When you want to compare nested data structures

WARNING

Array order does matter. ["a", "b"] is not equal to ["b", "a"].