Slow Tests Reorganization

Summary

Successfully reorganized slow tests to keep the test suite fast and responsive. Tests that take longer than 10 seconds are now separated from the main test suite.

Changes Made

1. Identified Slow Tests

  • xdl-matlab integration tests: These tests read files from disk and perform complex transpilation
    • control_flow_integration_test.rs - Tests control flow structures (switch/case, try/catch, loops)
    • array_literals_integration_test.rs - Tests array literal transpilation

2. Moved to Separate Directory

Created new directory structure:

slow_tests/
├── README.md                           # Documentation for slow tests
└── xdl-matlab/
    ├── control_flow_integration_test.rs
    └── array_literals_integration_test.rs

3. Added #[ignore] Attributes

Both tests now have:

#[test]
#[ignore = "Slow test: Integration test with file I/O"]
fn test_name() { ... }

4. Created Helper Script

  • run_slow_tests.sh - Shell script to easily run slow tests
  • Makes slow tests executable: chmod +x run_slow_tests.sh

5. Updated Documentation

  • README.md: Added section on running slow tests
  • slow_tests/README.md: Comprehensive guide for slow test management

Performance Improvement

Before 

cargo test --all: >120 seconds (timed out)

After 

cargo test --all: ~4.4 seconds ✓

Improvement: 27x faster (from >2 minutes to ~4 seconds)

Usage

Run Fast Tests (Default) 

cargo test --all
# Completes in ~4-6 seconds

Run Slow Tests 

# Option 1: Use the helper script
./run_slow_tests.sh

# Option 2: Run manually
cargo test -- --ignored

# Option 3: Run specific slow test
cd xdl-matlab
cargo test --test control_flow_integration_test -- --ignored

Benefits

  1. Fast Feedback Loop: Developers get test results in seconds, not minutes
  2. CI Optimization: Regular CI runs complete quickly
  3. Clear Separation: Obvious which tests are performance-sensitive
  4. Selective Execution: Run slow tests only when needed (e.g., before releases)
  5. Better Developer Experience: No more waiting minutes for test results

Guidelines for Future Tests

When adding new tests that might be slow:

  1. Estimate execution time: If likely >10 seconds, mark as slow
  2. Add #[ignore] attribute: Include descriptive reason
  3. Move to slow_tests/: Place in appropriate subdirectory
  4. Update documentation: Add to slow_tests/README.md
  5. Consider optimization: Can the test be made faster?

Examples of Slow Tests

Tests that should be marked as slow:

  • File I/O operations (reading large files)
  • Network operations (HTTP requests, database queries)
  • Heavy computation (ML training, complex simulations)
  • Integration tests (testing multiple components together)
  • Tests with sleep() or delays

Tests that should remain in main suite:

  • Unit tests (testing single functions)
  • Fast computation tests
  • Memory/allocation tests
  • Simple integration tests (<1 second)
  • /slow_tests/README.md - Detailed guide for slow tests
  • /run_slow_tests.sh - Script to run slow tests
  • /README.md - Updated with slow test information
  • /.pre-commit-config.yaml - Pre-commit hooks (still run fast tests)