Event testing in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to emit an event named Transfer.

Blockchain / Solidity

emit [1](msg.sender, recipient, amount);

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ADeposit

BApproval

CTransfer

DWithdraw

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong event name like Approval instead of Transfer.

Forgetting to emit the event.

The Transfer event is emitted to signal token transfers.

2fill in blank

medium

Complete the code to listen for the Approval event in a test.

Blockchain / Solidity

const filter = contract.filters.[1](owner, spender);

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AWithdraw

BApproval

CDeposit

DTransfer

Attempts:

3 left

💡 Hint

Common Mistakes

Using Transfer event filter when testing Approval.

Misspelling the event name.

The Approval event is used to track allowance changes.

3fill in blank

hard

Fix the error in the test assertion for event arguments.

Blockchain / Solidity

expect(event.args.[1]).to.equal(recipient);

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Asender

Bowner

Camount

Drecipient

Attempts:

3 left

💡 Hint

Common Mistakes

Using sender instead of recipient for the receiver address.

Confusing argument names.

The recipient argument holds the address receiving tokens.

4fill in blank

hard

Fill both blanks to filter events by sender and minimum amount.

Blockchain / Solidity

const filter = contract.filters.Transfer([1], null, [2]);

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AsenderAddress

BrecipientAddress

CminAmount

DmaxAmount

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping sender and recipient addresses.

Using maxAmount instead of minAmount.

The filter uses senderAddress to specify who sent tokens and minAmount to filter transfers above a value.

5fill in blank

hard

Fill all three blanks to assert event emission with correct args.

Blockchain / Solidity

await expect(tx).to.emit(contract, '[1]').withArgs([2], [3], amount);

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ATransfer

BsenderAddress

CrecipientAddress

DApproval

Attempts:

3 left

💡 Hint

Common Mistakes

Using Approval event instead of Transfer.

Swapping sender and recipient arguments.

The test expects the Transfer event with senderAddress and recipientAddress as first two arguments.