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How to Capture Screenshot on Test Case Failure With Pytest?

6 minutes read

To capture a screenshot on test case failure with pytest, you can use the pytest-screenshot plugin. First, install the plugin by running pip install pytest-screenshot. Then, import the plugin in your test file and add the pytest.mark.screenshot decorator to the test case that you want to capture a screenshot for. When the test case fails, the plugin will automatically capture a screenshot of the browser window at the point of failure. You can configure the plugin to save the screenshots in a specific directory or customize the naming convention for the screenshots. This feature can be useful for debugging and investigating the cause of test failures.


What is the best way to take a screenshot on test case failure with pytest?

The best way to take a screenshot on test case failure with pytest is to use the pytest-selenium plugin in combination with WebDriver. Here is a step-by-step guide on how to achieve this:

  1. Install the pytest-selenium plugin by running the following command:
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pip install pytest-selenium


  1. Make sure you have WebDriver installed for the browser you want to use. You can install WebDriver by visiting the official WebDriver website and downloading the appropriate driver for your browser.
  2. Create a fixture that initializes the WebDriver session in your conftest.py file: 
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import pytest
from selenium import webdriver

@pytest.fixture
def driver(request):
    driver = webdriver.Chrome() # Change this line to use a different browser
    request.addfinalizer(driver.quit)
    return driver


  1. Use the screenshot method provided by the pytest-selenium plugin to capture a screenshot on test case failure. You can do this by adding the following code snippet to your test case:
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def test_example(driver):
    driver.get('https://example.com')
    assert driver.title == 'Incorrect Title' # Force the test to fail
    driver.screenshot('failure.png')


  1. Run your test cases using the following command:
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pytest --capture=no


This will capture a screenshot named failure.png in the same directory where you run the test in case of test failure. You can customize the screenshot name and location as needed.


By following these steps, you can easily take a screenshot on test case failure with pytest using the pytest-selenium plugin.


What are the benefits of capturing screenshots on test case failure with pytest?

Capturing screenshots on test case failure with pytest can provide the following benefits:

  1. Visual evidence: Screenshots can provide visual evidence of the failure, making it easier for developers to understand what went wrong and troubleshoot the issue.
  2. Reproducibility: Screenshots can help in reproducing the failure by capturing the state of the application at the time of the failure.
  3. Debugging: Screenshots can provide additional information to assist in debugging the issue, such as error messages or unexpected behavior.
  4. Documentation: Screenshots can be used as documentation of the failure, helping in tracking and resolving the issue.
  5. Communication: Screenshots can be shared with team members to communicate the failure effectively and collaborate on finding a solution.


Overall, capturing screenshots on test case failure can improve the efficiency and effectiveness of the debugging process, leading to quicker resolution of issues.


What support is available for capturing screenshots on different platforms using pytest?

There are several ways to capture screenshots in pytest on different platforms:

  1. Using the pytest-selenium plugin: This plugin provides functionality for taking screenshots during tests that use Selenium WebDriver. It allows you to capture screenshots at various points in your test execution, such as when a test fails or when a specific condition is met. You can find more information and installation instructions for pytest-selenium here: https://pytest-selenium.readthedocs.io/en/latest/
  2. Using the pytest-html plugin: This plugin generates an HTML report of your test results, including screenshots of failed tests. It provides an easy way to capture and view screenshots during your test runs. You can find more information and installation instructions for pytest-html here: https://pytest-html.readthedocs.io/en/latest/
  3. Using the pytest-mozscreenshots plugin: This plugin provides a way to capture screenshots of webpages in Mozilla Firefox using pytest. It allows you to take screenshots of specific elements or regions of a webpage during your tests. You can find more information and installation instructions for pytest-mozscreenshots here: https://github.com/mikemusic/py.test-mozscreenshots


These are just a few examples of the support available for capturing screenshots in pytest on different platforms. There may be other plugins or tools that provide similar functionality, so it's worth exploring the pytest ecosystem to find the best solution for your specific needs.


How do I configure pytest to capture screenshots on test case failure?

You can use the pytest-screenshot plugin to capture screenshots on test case failure. Here's how you can configure pytest to capture screenshots:

  1. Install the pytest-screenshot plugin by running the following command:
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pip install pytest-screenshot


  1. Add the following configuration to your pytest.ini file or conftest.py file:
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[pytest]
addopts = --capture=tee-sys --continue-on-collection-errors
screenshot_dir = path_to_screenshot_directory


  1. Create a fixture in your test file to capture the screenshot on test case failure:
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import pytest
from pytest_selenium import Capture as SeleniumCapture

@pytest.fixture(scope='function')
def capture_screenshot(request):
    yield SeleniumCapture()
    if request.node.rep_call.failed:
        screenshot = request.node.screenshot_path()
        request.node.screenshot(filename=screenshot)


  1. Use the capture_screenshot fixture in your test cases to capture a screenshot on test case failure:
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def test_example(capture_screenshot):
    # Perform actions that may fail
    assert False, "Sample test case failure message"


Now, when a test case fails, pytest will capture a screenshot and save it to the specified directory.


How to ensure that screenshots are captured only on test case failure with pytest?

You can achieve this by using the pytest plugin pytest-screenshot. This plugin allows you to capture screenshots only when a test case fails.


To use pytest-screenshot, you first need to install the plugin by running:

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pip install pytest-screenshot


Next, you need to configure pytest to use the plugin by adding the following line to your pytest.ini or tox.ini file:

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[pytest]
addopts = --capture=fd


Now, you can use the snapshot fixture provided by pytest-screenshot in your test cases. Here's an example of how you can capture a screenshot only on test case failure:

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import pytest

@pytest.mark.screenshot
def test_example():
    # Your test code here
    assert False


In the above example, the @pytest.mark.screenshot decorator marks the test case to capture a screenshot only when the test case fails.pytest-screenshot will automatically take a screenshot when the test fails and save it to a specified directory.


By following these steps, you can ensure that screenshots are captured only on test case failure with pytest.


How to validate the accuracy of the captured screenshots from test case failures with pytest?

One way to validate the accuracy of the captured screenshots from test case failures with pytest is to visually inspect the screenshots yourself. You can open the screenshots on your computer or mobile device and compare them to the expected results to see if there are any discrepancies.


Another approach is to automate the validation process using image comparison tools or libraries. You can use tools like Pillow, OpenCV, or imagediff to compare the captured screenshot with a reference screenshot. These tools can analyze the pixel values of the images and identify any differences between them, allowing you to easily detect any inaccuracies.


Additionally, you can include assertions in your pytest test cases to validate the captured screenshots. You can write assertions to check for specific elements or patterns in the screenshots, ensuring that they match the expected results. This can help you quickly identify any discrepancies and determine the accuracy of the captured screenshots.


Overall, by visually inspecting the screenshots, using image comparison tools, and including assertions in your test cases, you can effectively validate the accuracy of the captured screenshots from test case failures with pytest.

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