error-scenario-testing

name	error-scenario-testing
description	Techniques for forcing error conditions in code to test error handling paths, including mock failure injection. Use when testing error handling, maze generation failures, or when error conditions are hard to trigger naturally. Create test scenarios to force error conditions and verify error handling works correctly.

Error Scenario Testing

Overview

Test error handling by forcing error conditions. Don't commit error handling code without testing error paths.

Forcing Error Conditions

Methods:

• Add test mode flags to enable error injection
• Create test seam commands to trigger errors
• Temporarily modify code to force failures (revert after testing)
• Use environment variables to enable error testing

See references/error-injection.md for detailed error injection patterns.

Maze Generation Error Testing

For maze generation failures:

• Add forceMazeFailure() test seam command
• Modify maze generation to fail after N attempts
• Test fallback maze creation
• Verify console warnings appear

See references/maze-generation-errors.md for specific patterns.

Error Testing Checklist

• Error condition can be triggered
• Error handling code executes
• Fallback behavior works correctly
• User experience is acceptable
• Console warnings/logs appear
• Game doesn't crash

Test Mode Pattern

See references/error-injection.md for test mode implementation pattern.

Test Seam Error Injection

Add test seam commands to trigger errors:

// Force error conditions via test seam
window.__TEST__.commands.forceMazeFailure = () => {
  // Force maze generation to fail
  this.mazeGenerator.forceFailure = true;
};

window.__TEST__.commands.restoreMazeGeneration = () => {
  // Restore normal maze generation
  this.mazeGenerator.forceFailure = false;
};

Error scenario test commands:

window.__TEST__.commands = {
  forceMazeFailure: () => {
    this.mazeGenerator.forceFailure = true;
  },
  restoreMazeGeneration: () => {
    this.mazeGenerator.forceFailure = false;
  },
  triggerAssetLoadError: () => {
    // Simulate asset load failure
    this.assetLoader.simulateError = true;
  },
  restoreAssetLoading: () => {
    this.assetLoader.simulateError = false;
  }
};

Test error handling paths:

# Test error scenario
agent-browser eval "window.__TEST__.commands.forceMazeFailure()"
agent-browser eval "window.__TEST__.commands.generateMaze()"
# Verify fallback behavior
agent-browser eval "window.__TEST__.commands.restoreMazeGeneration()"

Error Recovery Patterns

Retry logic with configurable attempts:

async function generateWithRetry(
  generator: () => Promise<Result>,
  maxAttempts: number = 3
): Promise<Result> {
  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
    try {
      return await generator();
    } catch (error) {
      console.warn(`Attempt ${attempt} failed:`, error);
      if (attempt === maxAttempts) {
        throw new Error(`Failed after ${maxAttempts} attempts`);
      }
      // Wait before retry
      await sleep(1000 * attempt); // Exponential backoff
    }
  }
  throw new Error('Max attempts reached');
}

Fallback mechanisms for critical operations:

async function loadAssetWithFallback(
  assetKey: string,
  primaryUrl: string,
  fallbackUrl: string
): Promise<void> {
  try {
    this.load.image(assetKey, primaryUrl);
  } catch (error) {
    console.warn(`Failed to load ${assetKey} from primary URL, using fallback`);
    this.load.image(assetKey, fallbackUrl);
  }
}

Console warning patterns:

if (!this.textures.exists('asset-key')) {
  console.warn('Asset not found:', 'asset-key');
  console.warn('Using fallback placeholder');
  // Use fallback
}

Graceful degradation strategies:

create() {
  try {
    // Try primary implementation
    this.initPrimaryFeature();
  } catch (error) {
    console.warn('Primary feature failed, using fallback:', error);
    // Graceful degradation
    this.initFallbackFeature();
  }
}

Verification Checklists

Verify error handling works:

## Error Handling Verification

- [ ] Error condition can be triggered
- [ ] Error handling code executes
- [ ] Fallback behavior works correctly
- [ ] User experience is acceptable
- [ ] Console warnings/logs appear
- [ ] Game doesn't crash

Test fallback mechanisms:

# Test fallback by forcing error
agent-browser eval "window.__TEST__.commands.forceMazeFailure()"
agent-browser eval "window.__TEST__.commands.generateMaze()"
# Verify fallback maze is created
agent-browser eval "window.__TEST__.gameState().maze"

Check console warnings:

# Check for console warnings
agent-browser console | grep -i "warn\|error"

# Verify warnings appear for error scenarios
agent-browser eval "window.__TEST__.commands.forceMazeFailure()"
agent-browser console

Validate recovery behavior:

# Test recovery after error
agent-browser eval "window.__TEST__.commands.forceMazeFailure()"
agent-browser eval "window.__TEST__.commands.generateMaze()"
agent-browser eval "window.__TEST__.commands.restoreMazeGeneration()"
agent-browser eval "window.__TEST__.commands.generateMaze()"
# Verify normal generation works after recovery

Resources

• references/error-injection.md - Test mode flags, test seam commands, environment variables
• references/maze-generation-errors.md - Specific patterns for maze generation failures