aaronbassett/compact-core:testing-debugging

Testing & Debugging

Essential guidance for testing Compact contracts, debugging common errors, and understanding compiler/runtime error messages.

Common Errors Quick Reference

| Error Message | Likely Cause | Quick Fix | |---------------|--------------|-----------| | potential witness-value disclosure | Witness flows to public output | Add disclose() or use commitment | | type mismatch | Incompatible types in operation | Check type signatures, use as for conversion | | unbounded loop | Loop bounds not compile-time constant | Use literal or #N parameter for bounds | | circuit constraint failed | Runtime assertion failed | Check assert conditions and inputs | | proof generation failed | Invalid witness values | Verify witness function returns valid data | | overflow | Arithmetic exceeds type bounds | Use larger Uint<N> or check bounds |

Debugging Decision Tree

Error during compilation?
├── "potential witness-value disclosure"
│   └── See: references/error-messages.md#disclosure-errors
├── "type mismatch" or "cannot convert"
│   └── See: references/error-messages.md#type-errors
├── "unbounded loop" or "bounds must be constant"
│   └── See: references/error-messages.md#loop-errors
└── Other compilation error
    └── See: references/error-messages.md

Error during proof generation?
├── "assert failed" or "constraint failed"
│   └── Check assertion conditions and witness values
├── "proof generation failed"
│   └── Verify witness functions return expected types
└── "overflow" or "division by zero"
    └── Check arithmetic bounds

Testing Approaches

Unit Testing Circuits

import { TestContext } from '@midnight-ntwrk/compact-testing';

describe('MyContract', () => {
    let ctx: TestContext;

    beforeEach(async () => {
        ctx = await TestContext.create('my_contract.compact');
    });

    it('should process valid input', async () => {
        const result = await ctx.call('process', [42n]);
        expect(result.success).toBe(true);
    });
});

Witness Mocking

const mockWitness = {
    get_secret: () => BigInt('12345'),
    get_balance: () => BigInt(1000)
};

const result = await ctx.call('transfer', [recipient], mockWitness);

State Verification

// Read ledger state after circuit execution
const balance = await ctx.ledger.get('balances', userKey);
expect(balance).toBe(expectedBalance);

Common Pitfalls

| Pitfall | Symptom | Solution | |---------|---------|----------| | Forgetting disclose() | Compile error | Add explicit disclosure | | Wrong ADT choice | Inefficient proofs | Use Counter for counting, MerkleTree for membership | | Attempting unbounded loops | Compile error | Use bounded for i in 0..N | | Uint overflow | Proof failure | Use larger bit width or check bounds | | Division by zero | Proof failure | Add zero check before division |

References

• Error Messages - Complete error reference with solutions
• Testing Strategy - Testing approaches and best practices
• Common Pitfalls - Frequent mistakes and how to avoid them

Examples

• Test Setup - TypeScript test harness configuration
• Mock Witnesses - Witness mocking patterns