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Testing On-Chain Randomness

Testing randomness requires special attention to ensure fair distribution and proper behavior.

Setting Up Tests​

Testing Initial State​

Verify players start with zero points:

Testing Randomness Distribution​

Verify both outcomes occur with reasonable frequency:

Running Tests​

# Run all tests
npm test

# Run with verbose output
npm test -- --verbose

# Run specific test file
npm test sandbox-test/main.ava.js

Test Best Practices​

1. Test Edge Cases​

test('handles minimum points correctly', async (t) => {
  // Ensure points don't go below 0
  const points = await contract.view('points_of', { 
    player: account.accountId 
  });
  t.true(points >= 0);
});

2. Mock Randomness for Unit Tests​

For deterministic testing, consider mocking:

#[cfg(test)]
fn mock_random_seed() -> [u8; 32] {
    [42; 32] // Fixed seed for testing
}

3. Integration Testing​

Test the full flow with multiple accounts:

test('multiple players maintain separate scores', async (t) => {
  const { root, contract } = t.context.accounts;
  const alice = await root.createSubAccount('alice');
  
  // Play as root
  await root.call(contract, 'flip_coin', { player_guess: 'heads' });
  
  // Play as alice
  await alice.call(contract, 'flip_coin', { player_guess: 'tails' });
  
  // Check separate scores
  const rootPoints = await contract.view('points_of', { player: root.accountId });
  const alicePoints = await contract.view('points_of', { player: alice.accountId });
  
  t.not(rootPoints, alicePoints); // Different players, different scores
});

With tests confirming our randomness works correctly, let's explore advanced patterns for more complex use cases.