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Testing and Deploying Advanced Cross-Contract Calls

Let's test our advanced patterns and deploy to NEAR testnet.

Testing with Sandbox​

import { Worker } from 'near-workspaces';
import test from 'ava';

test('batch actions execute atomically', async (t) => {
  const worker = await Worker.init();
  const root = worker.rootAccount;
  
  // Deploy contracts
  const main = await root.createSubAccount('main');
  await main.deploy('./build/cross_contract.wasm');
  
  const hello = await root.createSubAccount('hello');
  await hello.deploy('./tests/external-contracts/hello-near.wasm');
  
  // Initialize main contract
  await main.call('init', {
    hello_account: hello.accountId,
    counter_account: counter.accountId,
    guestbook_account: guestbook.accountId
  });
  
  // Test batch actions
  const result = await main.call('batch_actions', {});
  t.truthy(result);
  
  await worker.tearDown();
});

test('parallel execution handles failures', async (t) => {
  // Test with one contract failing
  const result = await main.call('multiple_contracts', {});
  
  // Should contain partial results
  t.true(result.includes('Hello:'));
  t.true(result.includes('failed'));
});

Running Tests​

npm test

# Output:
✓ batch actions execute atomically (5s)
✓ parallel execution handles failures (3s)
✓ callbacks process correctly (4s)

Deployment Steps​

1. Create Account​

near account create-account sponsor-by-faucet-service advanced-xcc.YOUR_NAME.testnet autogenerate-new-keypair save-to-keychain network-config testnet create

2. Build Contract​

npm run build

3. Deploy with Initialization​

near contract deploy advanced-xcc.YOUR_NAME.testnet use-file ./build/cross_contract.wasm with-init-call init json-args '{
  "hello_account": "hello.near-examples.testnet",
  "counter_account": "counter.near-examples.testnet",
  "guestbook_account": "guestbook.near-examples.testnet"
}' prepaid-gas '100.0 Tgas' attached-deposit '0 NEAR' network-config testnet sign-with-keychain send

Testing on Testnet​

# Batch actions
near contract call-function as-transaction advanced-xcc.YOUR_NAME.testnet batch_actions json-args '{}' prepaid-gas '300.0 Tgas' attached-deposit '0 NEAR' sign-as YOUR_ACCOUNT.testnet network-config testnet sign-with-keychain send

# Parallel execution
near contract call-function as-transaction advanced-xcc.YOUR_NAME.testnet multiple_contracts json-args '{}' prepaid-gas '300.0 Tgas' attached-deposit '0 NEAR' sign-as YOUR_ACCOUNT.testnet network-config testnet sign-with-keychain send

Production Checklist​

Security​

  • Validate external contract addresses
  • Implement access controls
  • Add callback validation
  • Test failure scenarios

Gas Optimization​

  • Profile gas usage
  • Set appropriate limits
  • Add gas monitoring

Error Handling​

  • Handle partial failures
  • Implement retry logic
  • Add comprehensive logging
  • Create fallback mechanisms

Common Issues​

Gas Exhaustion​

Error: Exceeded the prepaid gas

Solution: Increase gas allocation:

.functionCall("callback", args, 0n, 50_000_000_000_000n) // 50 TGas

Callback Failures​

Error: Promise result not found

Solution: Match index to promise order:

const result0 = getValueFromPromise(0); // First promise
const result1 = getValueFromPromise(1); // Second promise

Performance Benchmarks​

PatternGas UsageTime
Batch (3 calls)~60 TGas2-3 blocks
Parallel (3 contracts)~45 TGas1-2 blocks
Complex callback~15 TGas1 block

Monitoring​

# View transactions
near account view-account-summary advanced-xcc.YOUR_NAME.testnet network-config testnet now

# Check state
near contract view-state advanced-xcc.YOUR_NAME.testnet view-state all network-config testnet now

Summary​

You've mastered:

  • ✅ Batch actions with atomic rollback
  • ✅ Parallel execution for efficiency
  • ✅ Complex response handling
  • ✅ Testing with sandbox
  • ✅ Deploying to testnet

Next Steps​

  • Build complex DApps combining patterns
  • Optimize gas usage
  • Implement circuit breakers
  • Create reusable libraries

Resources​

Congratulations! You can now build sophisticated multi-contract applications on NEAR!