Writing test cases in Blockchain / Solidity - Mini Project: Build & Apply

Writing Test Cases for a Simple Blockchain

📖 Scenario: You are working on a simple blockchain project. To make sure your blockchain works correctly, you need to write test cases that check its basic functions.

🎯 Goal: Build test cases to verify the blockchain's ability to add blocks and validate the chain.

📋 What You'll Learn

Create a blockchain list with initial data

Set a variable for the expected chain length

Write a test function to check adding a block

Print the test results

💡 Why This Matters

🌍 Real World

Writing test cases helps ensure that blockchain code works correctly before it is used in real applications.

💼 Career

Blockchain developers must write tests to verify their code, which is critical for security and reliability in blockchain projects.

1

Create the initial blockchain data

Create a list called blockchain with these exact dictionaries as blocks: {'index': 1, 'data': 'Genesis Block'} and {'index': 2, 'data': 'Second Block'}

Blockchain / Solidity

# Your code here

Need a hint?

Use a list with two dictionaries exactly as shown.

2

Set the expected chain length

Create a variable called expected_length and set it to 3

Blockchain / Solidity

blockchain = [
    {'index': 1, 'data': 'Genesis Block'},
    {'index': 2, 'data': 'Second Block'}
]
# Your code here

Need a hint?

Just assign the number 3 to expected_length.

3

Write a test function to add a block

Write a function called test_add_block() that adds a new block {'index': 3, 'data': 'Third Block'} to blockchain and returns len(blockchain) == expected_length

Blockchain / Solidity

blockchain = [
    {'index': 1, 'data': 'Genesis Block'},
    {'index': 2, 'data': 'Second Block'}
]
expected_length = 3
# Your code here

Need a hint?

Define the function exactly as named and append the new block inside it.

4

Print the test result

Write a print statement that calls test_add_block() and prints 'Test passed' if it returns true, otherwise prints 'Test failed'

Blockchain / Solidity

blockchain = [
    {'index': 1, 'data': 'Genesis Block'},
    {'index': 2, 'data': 'Second Block'}
]
expected_length = 3

def test_add_block():
    blockchain.append({'index': 3, 'data': 'Third Block'})
    return len(blockchain) == expected_length

# Your code here

Need a hint?

Use an if statement to check the function result and print the correct message.