Kursinnehåll

Python Advanced Concepts

1. Mastering Python Modules and Imports

Python Project Structure: Organizing Code for Scalability Understanding Python Modules Importing Modules in Python: Best Practices for Code Reusability Exploring Python Libraries: Built-in and Third-Party Solutions Python Standard Library: Essential Modules for Everyday Tasks Managing Python Packages

2. Mastering Error Handling in Python

Fundamentals of Error Handling in Python: Preventing Code Crashes Raising Exceptions in Python: Triggering and Managing Errors Executing Code After Exceptions: Handling Cleanup Operations Using Assertions in Python: Debugging and Ensuring Code Integrity Best Practices for Exception Handling

3. Mastering File Handling in Python

Introduction to File Handling in Python Reading and Writing Files: Handling Text and Data Efficiently Advanced File Operations: Modifying and Managing File Content Working with File Paths in Python Using Context Managers for File Handling in Python Creating Custom Context Managers Handling Binary Files in Python

4. Mastering Pytest Framework

Introduction to Testing in Python Pytest Framework: Setting Up and Running Automated Tests Using the Assert Statement in Pytest: Validating Test Conditions Test Parametrization in Pytest: Running Tests with Multiple Inputs

5. Mastering Unittest Framework

Introduction to Unittest in Python: Writing Structured Unit Tests Using Assert Methods in Unittest: Validating Test Results SetUp and TearDown in Unittest: Managing Test Environments Mocking Techniques in Unittest: Simulating Dependencies Advanced Mocking in Unittest

6. Mastering Iterators and Generators in Python

Python Iterables: Understanding Sequences and Data Structures Understanding Iterators in Python Lazy Evaluation in Python: Optimizing Memory and Performance Introduction to Generators: Yielding Values for Efficient Iteration Practical Applications of Generators: Real-World Use Cases

Mocking Techniques in Unittest: Simulating Dependencies

Testing code that depends on external services, configurations, or has side effects can be challenging. Mocking is a powerful technique that simulates the behavior of complex real-world interactions within tests without their complexity and unpredictability.

For instance, if you need to test a money exchange service, one option could involve using your own funds to simulate transactions and observe the outcomes. However, this method can be risky and costly. A more efficient and risk-free alternative is to use mocking to emulate the process of sending money.

Testing a Money Transfer Service

class MoneyTransferService:
    def transfer(self, source_account, destination_account, amount):
        if source_account.balance < amount:
            raise ValueError("Insufficient funds")
        source_account.balance -= amount
        destination_account.balance += amount
        return True

The Testing Approach:

Mock the Account Balances: use mocking to simulate different account states, such as insufficient funds or ample funds, to test how the transfer method responds;
Verify Transactions: confirm that the appropriate amounts are debited and credited from the respective accounts during a transfer;
Handle Exceptions: ensure that the method correctly handles scenarios where the transfer cannot be completed.

import unittest
from unittest.mock import MagicMock

class TestMoneyTransferService(unittest.junit.TestCase):
    def setUp(self):
        self.transfer_service = MoneyTransferService()
        self.source_account = MagicMock()
        self.destination_account = MagicMock()

    def test_successful_transfer(self):
        # Set up the account balances
        self.source_account.balance = 1000
        self.destination_account.balance = 500

        # Perform the transfer
        successful = self.transfer_service.transfer(self.source_account, self.destination_account, 200)
        
        # Check balances
        self.assertTrue(successful)
        self.assertEqual(self.source_account.balance, 800)
        self.assertEqual(self.destination_account.balance, 700)

    def test_failed_transfer_due_to_insufficient_funds(self):
        # Set up the account balances
        self.source_account.balance = 100
        self.destination_account.balance = 500

        # Attempt to transfer more than the source balance
        with self.assertRaises(ValueError):
            self.transfer_service.transfer(self.source_account, self.destination_account, 200)
        
        # Verify that balances remain unchanged
        self.assertEqual(self.source_account.balance, 100)
        self.assertEqual(self.destination_account.balance, 500)

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