Vfsstream Laravel Package

Getting Started

Install via Composer: composer require --dev mikey179/vfsstream. Start by replacing direct filesystem operations in your tests with vfsStream::url('root/some/file.txt') and set up your virtual filesystem using vfsStream::setup('root', $structure). The most common first use case: mocking file reads/writes in a service class during unit tests—e.g., test a config reader without touching real files.

Implementation Patterns

• Use vfsStream::setup() at the beginning of a test (e.g., in setUp() or inline) to define directory/file hierarchy with optional content or custom file content types (vfsStreamContent, vfsStreamDirectory).
• Use vfsStream::url('root') as the base stream URL for all simulated I/O. Replace file_get_contents('/path/to/config.yml') with file_get_contents(vfsStream::url('root/config.yml')).
• For custom behavior, implement org\bovigo\vfs\content\Content or extend vfsStreamFile to simulate special file types (e.g., empty but writable file, or one that throws on write).
• Combine with PHPUnit’s ::setUpBeforeClass() or ::assertFileEquals() to validate expected outputs.
• For stream context simulation (e.g., stream_context_create()), set it via vfsStreamWrapper::setContext() before usage—especially useful for testing wrapper options or vfsStreamWrapper::register()/::unregister() in isolation tests.

Gotchas and Tips

• vfsStream::path() (deprecated) and vfsStream::url() differ: url() returns the full stream wrapper URL (vfs://root/file.txt), while path() returns a normalized path relative to root—but avoid path() as it's deprecated.
• File/directory names in structure arrays must be scalar strings; using integers (e.g., 0) as keys or names requires care—v1.6.3+ fixes some edge cases here.
• PHP 8.4 requires explicit nullable type hints; ensure your custom content implementations match exact signatures (write() must return int|false, not just int).
• Avoid relying on hard-coded php://stream aliases—use vfsStreamWrapper::register()/::unregister() explicitly when testing stream wrapper registrations.
• When mocking real-world scenarios like fopen() with 'w+', ensure the target file or parent directory exists (create via vfsStream::create() or full structure), as vfsStream emulates real filesystem path existence checks.
• Debug tip: enable verbose output in tests with var_dump(vfsStream::root()->children()) to inspect the virtual structure after operations.