Python Modules and Packages

Modules and Packages in Python help organize code into reusable and manageable units. They play a very important role in building large applications and automation frameworks.

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What is a Module in Python?

A module is a Python file that contains variables, functions, and classes. Any file with a .py extension is considered a module.

Example of a Module

# math_utils.py

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

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Importing a Module

Using import

import math_utils

print(math_utils.add(10, 5))

Using from import

from math_utils import add

print(add(10, 5))

Import with Alias

import math_utils as mu

print(mu.subtract(10, 5))

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Built-in Modules in Python

Python provides many built-in modules that can be used directly.

• math
• os
• sys
• datetime
• random

Example

import math

print(math.sqrt(16))

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What is a Package in Python?

A package is a collection of related modules organized in directories. It helps manage large projects efficiently.

Package Structure

project/
│
├── utils/
│   ├── __init__.py
│   ├── file_utils.py
│   └── string_utils.py
│
└── main.py

Note: The __init__.py file tells Python that the directory should be treated as a package.

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Importing from a Package

from utils.file_utils import read_file

from utils import string_utils

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Example of Module inside a Package

# utils/file_utils.py

def read_file(filename):
    print("Reading file:", filename)

# main.py

from utils.file_utils import read_file

read_file("data.txt")

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__name__ == "__main__"

This condition checks whether the file is run directly or imported as a module.

def show():
    print("Hello Python")

if __name__ == "__main__":
    show()

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Installing External Packages (pip)

Python uses pip to install third-party packages.

pip install requests

Using Installed Package

import requests

response = requests.get("https://example.com")
print(response.status_code)

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Modules and Packages in Automation Testing

framework/
│
├── pages/
│   ├── login_page.py
│   └── dashboard_page.py
│
├── tests/
│   └── test_login.py
│
└── utils/
    └── config_reader.py

Used in:

• Selenium Page Object Model
• Robot Framework libraries
• API automation frameworks

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Difference Between Module and Package

Module	Package
Single Python file	Collection of modules
.py file	Directory
Easy to create	Used for large projects

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Best Practices

• Keep related code in same package
• Use meaningful module names
• Avoid circular imports
• Use virtual environments

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Common Interview Questions

• What is a module?
• What is a package?
• Difference between module and package?
• What is __init__.py?
• What is __name__ == "__main__"?

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Conclusion

Modules and packages help organize Python code efficiently. They are essential for building scalable applications and automation testing frameworks.

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