Assertion patterns in Blockchain / Solidity

Introduction

Assertion patterns help check if something is true in your blockchain code. They stop the program if a mistake happens, keeping your data safe.

To make sure a transaction has enough funds before sending.

To check if a user is authorized before allowing access.

To verify that a smart contract's state is correct after an action.

To catch errors early during blockchain development.

To prevent invalid data from being saved on the blockchain.

Syntax

Blockchain / Solidity

assert condition, "error message"

The assert keyword checks if the condition is true.

If the condition is false, the program stops and shows the error message.

Examples

This checks if the balance is enough to cover the amount before sending money.

Blockchain / Solidity

assert balance >= amount, "Insufficient funds"

This ensures only the owner can perform certain actions.

Blockchain / Solidity

assert user == owner, "Unauthorized access"

This confirms the contract's state is as expected after an update.

Blockchain / Solidity

assert state == expected_state, "State mismatch"

Sample Program

This program checks if the balance is enough to send the amount. If not, it stops with an error.

Blockchain / Solidity

balance = 100
amount = 150
assert balance >= amount, "Insufficient funds"
print("Transaction approved")

Important Notes

Assertions are great for catching mistakes early but should not replace normal error handling.

In blockchain, stopping on errors helps protect funds and data integrity.

Summary

Assertions check if something is true and stop the program if not.

They help keep blockchain data safe by catching errors early.

Use clear error messages to understand what went wrong.