Testing API Pagination and Filter Edge Cases

API pagination tests must cover zero, large and invalid page sizes, empty pages and sorting stability.

What It Does

API pagination tests must cover zero, large and invalid page sizes, empty pages and sorting stability. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

PHP 8.x and a local test environment. Apply input validation, correct error handling and the requirements of any optional libraries.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

Understand the primary operation and its inputs.

<?php
function pageLimit(int $limit): int { return max(1, min(100, $limit)); }
foreach ([0, 10, 1000] as $value) { assert(pageLimit($value) >= 1); }
echo 'Boundaries checked';

Example 2: Another Case

Check failure behavior or a different execution path.

<?php
function classify(int $status): string { return $status >= 500 ? 'server' : ($status >= 400 ? 'client' : 'ok'); }
$cases = [[200, 'ok'], [404, 'client'], [503, 'server']];
foreach ($cases as [$code, $expected]) { if (classify($code) !== $expected) throw new RuntimeException('Test failed'); }
echo 'Cases passed';

Practical Example: Putting It to Use

Apply the behavior in a small, controlled scenario.

<?php
$eventIds = ['evt-1', 'evt-1', 'evt-2'];
$seen = [];
foreach ($eventIds as $id) { if (isset($seen[$id])) continue; $seen[$id] = true; }
assert(count($seen) === 2);
echo 'Idempotent scenario passes';

Important Behavior and Edge Cases

Offset pagination can produce duplicates or gaps when rows are inserted during navigation.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• API pagination tests must cover zero, large and invalid page sizes, empty pages and sorting stability.
• Offset pagination can produce duplicates or gaps when rows are inserted during navigation.
• Keyset pagination is useful for very large or fast-changing tables.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.