The Case Sensitivity Bug That Broke My Laravel Inertia Tests: A Cross-Platform Development Tale

Preliminary Information

macOS (Case-Insensitive by Default)

• macOS uses HFS+ or APFS file systems, which are case-insensitive by default
• This means Index and index are treated as the same file/directory
• Your application works regardless of the case mismatch

Linux/Ubuntu (Case-Sensitive)

• Linux file systems (ext4, etc.) are case-sensitive
• Index and index are treated as completely different files/directories
• If your actual directory is named index but your config references Index, the path resolution fails

When developing web applications across different operating systems, we often encounter subtle bugs that work perfectly on one platform but fail mysteriously on another. Today, I want to share a particularly frustrating case sensitivity issue I encountered with Laravel Inertia.js that cost me 2 hours of debugging and how a simple configuration change solved everything.

The Problem: Tests Passing Locally, Failing in CI

Picture this scenario: You’ve written a comprehensive test suite for your Laravel application using Inertia.js. Everything works flawlessly on your local macOS development environment with PHP 8.4. Your tests pass, your application runs smoothly, and you’re confident in your code.

Then you push to your GitHub repository, and suddenly your CI pipeline starts failing with mysterious errors. The same tests that pass locally are now breaking in the Ubuntu environment of GitHub Actions.

Here’s the test that was causing all the trouble:

#[Test]
public function it_can_show_appointments_index()
{
    $this->actingAs($this->doctorUser)
        ->get(route('doctor.appointments.index'))
        ->assertStatus(200)
        ->assertInertia(function (AssertableInertia $page) {
            return $page->component('Doctor/Appointments/Index')
                ->has('appointments')
                ->has('availableSlots');
        });
}

This test was designed to verify that the doctor appointments index page loads correctly with the expected Inertia.js component and data. Simple enough, right?

Annnnd the error which we got in GitHub Actions:

Alright, first I thought the error was about case sensitivity issue because it’s the first thing it comes to mind, then i tried to change the file name to lowercase:

Still no luck! It’s the moment where i thought i must start to debugging.

The Debugging Journey

After encountering this issue, I went through the typical debugging checklist:

1. Environment Variables: Checked if all necessary environment variables were properly set in the CI environment
2. Dependencies: Verified that all PHP and Node.js dependencies were correctly installed
3. Database Setup: Ensured the test database was properly seeded
4. File Permissions: Checked if there were any file permission issues in the CI environment
5. PHP Version Compatibility: Confirmed PHP 8.4 compatibility across platforms

Everything seemed to be in order, yet the tests continued to fail in the Ubuntu CI environment while passing perfectly on macOS.

Lastly, i created a case-sensitive macOS Volume and started to step-debug the test itself, we were failing in the line 63 of AssertableInertia.php :

That wasn’t enough to learn the main problem, i went to deeper in FileViewFinder class and debugged it:

Did you notice the problem?

The Eureka Moment: Pages Directory

I discovered the root cause: case sensitivity in pages directory. But why was it like this? Why Inertia looks that folder with ‘Pages’ instead of ‘pages’? I had to look deeper.

Understanding the Root Cause

I started to debug from beginning, which in AssertableInertia.php:

app('inertia.testing.view-finder')->find($value);

Then i went to find method:

public function find($name)
{
    if (isset($this->views[$name])) {
        return $this->views[$name];
    }

    if ($this->hasHintInformation($name = trim($name))) {
        return $this->views[$name] = $this->findNamespacedView($name);
    }

    return $this->views[$name] = $this->findInPaths($name, $this->paths);
}

I had to find where that $this->paths coming from, so i searched and find that it was set in __construct.

Then I put a Breakpoint at line 57 and find the caller method of construct:

Which lead me to this code block:

Annnnnddd the moment of pain:

All of it was in a config file and waiting us to be changed to a lowercase…

The Solution and Best Practices

Immediate Fix

Update your config/inertia.php to match the actual case of your directory structure:

'page_paths' => [
    resource_path('js/pages'),
],

Prevention Strategies

1. Consistent Naming Convention: Establish and stick to a consistent case convention for directories (I recommend lowercase for better cross-platform compatibility)
2. Cross-Platform Testing: If possible, test your application on both case-sensitive and case-insensitive systems before deployment
3. CI/CD Pipeline: Always include comprehensive tests in your CI/CD pipeline running on Linux environments
4. Directory Structure Documentation: Document your project’s directory structure and naming conventions for team members

Lessons Learned

This experience reinforced several important principles:

1. Platform Differences Matter: Never assume that something working on one OS will work identically on another
2. Case Sensitivity is Critical: Always be mindful of case sensitivity when working with file paths
3. CI/CD is Essential: Continuous integration pipelines catch these platform-specific issues before production
4. Simple Solutions: Sometimes the most frustrating bugs have the simplest solutions

Conclusion

What started as a mysterious test failure turned into a valuable lesson about cross-platform development. A single character case difference caused hours of debugging, but ultimately led to a better understanding of how different operating systems handle file paths.

If you’re working with Laravel Inertia.js (or any framework that relies on file path resolution), always double-check that your configuration matches the actual case of your directory structure. Your future self and your CI pipeline will thank you.

Have you encountered similar cross-platform issues in your development journey? I’d love to hear about your experiences in the comments below.

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