# Informational Tests

This directory contains tests that are not part of the standard test suite. These tests are provided for informational purposes only and should be run separately.

## Purpose

Informational tests are designed to:
- Explore simulation boundaries and limits
- Provide diagnostic information about the simulation
- Test extreme or edge cases that don't fit into normal test suites
- Help understand system behavior under various conditions

## Running Informational Tests

Informational tests are **not** run by `make test`. To build and run them:

```bash
cd tests/informational
make
./time_step_test
```

## Current Tests

### `test_time_step_stability.cpp`

Determines the maximum stable time step for the RK4 integration across different orbital regimes.

**Test Bodies:**
- **Mercury Orbiter** (MESSENGER-like): 200 km altitude, ~12 hour period
- **Io** (Jupiter's moon): 421,700 km orbit, ~1.77 day period
- **Moon** (Earth's moon): 384,400 km orbit, ~27.3 day period

**Stability Criteria:**
- Energy drift < 1% over 100 orbits
- Distance drift < 5%
- No SOI transitions (body doesn't change parent)

**Configuration:** Uses `test_time_step_stability.toml`

**Usage:**
```bash
# From project root directory:
./tests/informational/test_time_step_stability

# Or using the Makefile:
cd tests/informational
make run-timestep

# Run specific test case
./tests/informational/test_time_step_stability '[timestep][stability]'

# Run with verbose output to see binary search progress
./tests/informational/test_time_step_stability -s "[timestep][stability]"
```

**Note:** Tests must be run from the project root directory because config file paths are relative to the root.

**Expected Output:**
The test performs a binary search to find the maximum stable time step, printing progress for each dt value tested. Results show the minimum stable dt across all tested bodies with recommendations.

## Adding New Informational Tests

1. Create a new `.cpp` file in this directory
2. Add corresponding `.toml` config file if needed
3. Add a target in the `Makefile`:
   ```makefile
   your_test_name: your_test_name.o
   	g++ $(BUILD_DIR)/*.o -o $@ -lCatch2Main -lCatch2 -lm
   ```
4. Update this README with test description
5. Follow the naming convention: `test_<purpose>.cpp` and `test_<purpose>.toml`