Automated Software Testing with Python's Selenium and Behave

Introduction
Prerequisites
Installation
Getting Started
Creating a Test Scenario
Running Tests
Common Errors and Troubleshooting
Frequently Asked Questions
Conclusion

Introduction

Automated software testing is an essential practice in modern software development. It helps ensure the quality and reliability of your software by automatically executing test scenarios and verifying expected outcomes. In this tutorial, we will learn how to perform automated software testing using Python’s Selenium library and the Behave framework.

By the end of this tutorial, you will be able to write automated tests that simulate user interactions with a web application, validate expected outputs, and generate comprehensive test reports. We will cover the installation and setup process, creating test scenarios, running tests, troubleshooting common errors, and answering frequently asked questions.

Prerequisites

To follow along with this tutorial, you should have a basic understanding of Python programming and web development concepts. Familiarity with HTML, CSS, and JavaScript will be helpful but not mandatory. Additionally, make sure you have Python installed on your system.

Installation

Before we can start using Selenium and Behave, we need to install the necessary dependencies.

Open your command prompt or terminal.
Create a new Python virtual environment (optional but recommended):
```
 python -m venv myenv
```

Activate the virtual environment:

On Windows:
```
  myenv\Scripts\activate.bat
```
On macOS/Linux:
```
  source myenv/bin/activate
```

Install Selenium and Behave using pip:
```
 pip install selenium behave
```
Download and install the appropriate web driver for your browser. Selenium requires a separate web driver to interact with each browser. For example, if you are using Google Chrome, you will need the ChromeDriver.

You can find the web drivers on the official Selenium website: https://www.selenium.dev/documentation/en/webdriver/driver_requirements/

Make sure to add the location of the web driver executable to your system’s PATH environment variable.

Getting Started

Let’s start by creating a basic project structure for our automated tests:

Create a new directory for your project:

 mkdir automated_tests
 cd automated_tests

Inside the automated_tests directory, create the following directory structure:
```
 ├── features
 │   └── steps
 └── utils
```
- The features directory will contain our test scenarios written in Gherkin syntax.
- The steps directory will contain the Python code that maps the Gherkin steps to actual test code.
- The utils directory will store any helper functions or classes that we might need.

Now, let’s create a new feature file in the features directory. Create a file called search.feature and add the following content:

 Feature: Search feature

 Scenario: Searching for a product
     Given I am on the homepage
     When I search for "iPhone"
     Then I should see search results

Next, we’ll create a Python file inside the steps directory to implement the step definitions. Create a file called search_steps.py and add the following content:

 from behave import given, when, then

 @given('I am on the homepage')
 def step_given_i_am_on_homepage(context):
     # Implement the code to navigate to the homepage
     pass

 @when('I search for "{product}"')
 def step_when_i_search_for_product(context, product):
     # Implement the code to search for the product
     pass

 @then('I should see search results')
 def step_then_i_should_see_search_results(context):
     # Implement the code to assert the presence of search results
     pass

Congratulations! You have set up your project structure and created a basic feature file and step definitions. Now let’s move on to running the tests.

Creating a Test Scenario

In this section, we will dive into creating a more detailed test scenario using Gherkin syntax. Open the search.feature file and modify it as follows: ```gherkin Feature: Search feature

Scenario: Searching for a product
    Given I am on the homepage
    When I search for "iPhone"
    Then I should see search results
    And the results should contain the word "Apple"
``` We have added an additional step to validate that the search results contain the word "Apple". This allows us to perform more granular checks on the expected behavior of our application.

Next, let’s update the step definitions in search_steps.py to implement this new step: ```python from behave import given, when, then

@given('I am on the homepage')
def step_given_i_am_on_homepage(context):
    # Implement the code to navigate to the homepage
    pass

@when('I search for "{product}"')
def step_when_i_search_for_product(context, product):
    # Implement the code to search for the product
    pass

@then('I should see search results')
def step_then_i_should_see_search_results(context):
    # Implement the code to assert the presence of search results
    pass

@then('the results should contain the word "{word}"')
def step_then_results_should_contain_word(context, word):
    # Implement the code to assert that the search results contain the given word
    pass
``` We have added a new step definition called `step_then_results_should_contain_word` to validate if the results contain the expected word.

Running Tests

Once we have our test scenarios defined, we can execute them using the Behave framework.

To run the tests, open your command prompt or terminal and navigate to the project’s root directory (automated_tests). Then, execute the following command: shell behave Behave will automatically discover the feature files and step definitions in the project and execute the corresponding test scenarios. You should see the output and status of each test scenario in the console.

Common Errors and Troubleshooting

Missing web driver executable: If you encounter an error related to the web driver executable not found, ensure that you have downloaded the correct web driver for your browser and added the executable’s location to the system’s PATH environment variable.
Element not found: If you are trying to interact with an element on a web page, make sure the element is present in the HTML source code and properly loaded before interacting with it. You can use implicit or explicit waits to handle element visibility and presence.
Incorrect CSS or XPath selector: When using Selenium to locate elements using CSS selectors or XPath expressions, make sure your selectors are correctly targeting the desired elements. You can use browser developer tools to inspect elements and verify their attributes.

Frequently Asked Questions

Q: Can I use Selenium with other browsers besides Chrome?
A: Yes, Selenium supports multiple browsers like Firefox, Microsoft Edge, Safari, etc. You need to download and configure the corresponding web driver for your chosen browser.

Q: Can I run tests in parallel using Behave?
A: Yes, Behave supports parallel test execution. You can pass the --processes argument to the behave command, specifying the number of parallel processes you want to run.

Q: How can I take screenshots during test execution?
A: Selenium provides a method called save_screenshot() that allows you to capture a screenshot of the current browser window. You can call this method at any point in your test code to save screenshots for debugging purposes.

Conclusion

In this tutorial, we have covered the basics of automated software testing using Python’s Selenium library and the Behave framework. We learned how to install the necessary dependencies, set up a project structure, write test scenarios using Gherkin syntax, and execute tests using Behave.

Automated software testing is a powerful technique to ensure the quality and reliability of your applications. You can now apply this knowledge to write comprehensive and robust test suites for your web applications. Remember to always follow best practices, such as creating reusable and maintainable test code, and leverage the extensive capabilities of Selenium and Behave to test various aspects of your web application.

Continue exploring the official documentation of Selenium and Behave to learn more advanced features and improve your automated testing skills.

Happy testing!

Published: 10 March 2023