Back to Repositories

Testing File Descriptor Handling Implementation in Textualize/rich

This test suite validates the get_fileno functionality in Rich library, focusing on file descriptor handling and error cases. The tests verify proper file descriptor retrieval and graceful handling of missing or broken fileno implementations.

Test Coverage Overview

The test suite provides comprehensive coverage of the get_fileno function, examining three key scenarios:

Valid fileno implementation returning an integer descriptor
Missing fileno method handling
Exception handling for broken fileno implementations

The tests ensure robust file descriptor management across different file-like object implementations.

Implementation Analysis

The testing approach uses mock FileLike classes to simulate different file descriptor scenarios. Each test case implements a specific variation of the fileno method, allowing isolated testing of success and failure paths. The implementation leverages Python’s class-based mocking to create controlled test conditions.

Technical Details

Testing tools and configuration:

Python’s built-in assert statements for verification
Custom FileLike class implementations
Exception handling verification
Integer return type annotations

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases for each scenario
Clear test method naming reflecting purpose
Type annotations for better code clarity
Comprehensive error case coverage
Minimal test case implementation

textualize/rich

tests/test_getfileno.py

            
from rich._fileno import get_fileno


def test_get_fileno():
    class FileLike:
        def fileno(self) -> int:
            return 123

    assert get_fileno(FileLike()) == 123


def test_get_fileno_missing():
    class FileLike:
        pass

    assert get_fileno(FileLike()) is None


def test_get_fileno_broken():
    class FileLike:
        def fileno(self) -> int:
            1 / 0
            return 123

    assert get_fileno(FileLike()) is None