Why is regression testing necessary?

Regression testing is necessary for:

• Verifying stability: Ensuring that new changes (bug fixes, new features) do not disrupt existing functionality of the software.
• Ensuring compatibility: Checking that changes do not lead to conflicts with other parts of the system or dependencies.
• Maintaining quality: Guaranteeing that the quality of the product does not deteriorate over time and with the addition of new versions.
• Reducing risks: Minimizing the likelihood of critical defects appearing in release versions.
• Saving time and resources: Automating regression testing allows for quick and repeated verification of large code volumes, reducing manual effort.

Without regression testing, releasing new features or bug fixes can lead to the emergence of new, often unpredictable defects in parts of the system that previously worked correctly. This can negatively impact user experience, the company's reputation, and lead to additional costs for fixing identified issues.

Automating regression tests enables regular and efficient checks, especially in projects with frequent changes.

# Example of a simple auto-test for basic authorization
def test_successful_login(driver):
    driver.get("http://example.com/login")
    driver.find_element_by_id("username").send_keys("testuser")
    driver.find_element_by_id("password").send_keys("password123")
    driver.find_element_by_id("login_button").click()
    assert "Dashboard" in driver.title # Check that the page changed to Dashboard

# This test can be part of a regression suite,
# to ensure that authorization works after changes.