Laravel Feature Tests Using Regex Patterns

I recently created a Laravel app that implemented swappable repositories to create random numbers. One of the repositories would be injected into a controller. The app is actually a tutorial/demo to show off Laravel’s Automatic Injection and random number generators seemed like an interesting way to demonstrate how to inject one particular implementation out of several. I decided to create one implementation using the standard random number generator, another using the Mersenne Twister generator, and a third using a cryptographically secure generator.

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I often use TDD in my process so the first test I wrote was to test for the generation of a random number. My test would drive my implementation. I created a Feature test using http-test and quickly realized that the available assertions did not contain any regex style assertions. All I wanted to do was assert that the returned content include a random number between 0 and 100. A simple pattern match on a regex of 1 to 3 digits would do nicely. But how to do this?

Laravel’s http-test capabilities are intended to make testing APIs, URLs and fixed content simple. Unfortunately, a regex pattern matching assertion is not included. To solve this shortcoming, I needed to get the actual rendered content and use PHPUnit assertions. This turned out to be quite easy since http-test tests are a superset of PHPUnit and all PHPUnit assertions are already available. This approach can be used to leverage any PHPUnit style assertion or even create a custom assertion when needed.

This example assumes a controller and route that will generate a string that includes a random number.

We need a route to invoke the controller.

The rendered page is available in $response->getContent(). This can be matched using PHPUnit’s assertRegExp() assertion. You can obviously use any PHPUnit assertion or even create a more complex assertion when required.

Here’s a similar example with subtle differences. The rendered page shows a number between 0 and 100. I wanted a single assertion that verified the number to be in that range.

Sometimes a simple assertSeeText() is sufficient, but sometimes you need more flexibility. Even though Laravel is missing http-test regex assertions out-of-the-box, they are really easy to add when needed.

Testing may seem difficult, confusing, and time consuming, but I find that testing speeds up my process in the long run. And I have much more confidence in my work when I have tests to prove that it works as intended. Finally, I get the benefit of a nice regression suite that grows with the code.

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Happy testing with regex patterns!

Download the code here.

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