Automated Regression Testing: Tutorial and Guide

Regression testing ensures that existing functions work as expected after code changes, such as adding new features or fixing bugs. While important, manual regression testing is often repetitive, making it a perfect candidate for automation.

As code releases become more frequent, automated regression testing ensures code stability while enabling rapid code delivery and quick responses from development teams. By incorporating automated regression testing, developers gain greater confidence in managing their code all the way through production. This approach not only disperses testing responsibilities across the team but also fosters a culture of accountability and ownership within the organization.

Summary of key automated regression testing concepts

What is regression testing?

Freshly added code can introduce new logic that clashes with previously written code, resulting in errors or bugs. In regression testing, development and QA teams validate that changes to the code, such as new functionalities or bug fixes, have not caused unexpected issues. The risk of unpredicted effects is heightened in large and complex applications.

Early identification of defects during regression testing enables the development team to make rapid corrections. Finding and fixing issues early in the software development cycle significantly reduces maintenance requirements and saves time and money, particularly in agile environments. In addition, addressing these defects before they affect the end-user enhances the overall quality and reliability of the software.

Regression testing vs. retesting

Retesting is a process where previously identified bugs are reverified to validate that they were corrected. It is sometimes mistaken for regression testing, but the two are separate concepts. They both require running tests again, but in different contexts and with different goals.

In short, retesting means executing again tests that previously failed in order to check that they now pass. Regression testing means executing tests that previously passed to validate that they still pass after changes have been made. The table below provides a more complete list of the differences:

Regression testing techniques

The three most popular regression testing methods are test case prioritization, test selection, and retesting everything.

Test case prioritization

When using this technique, a team selects which test cases to prioritize during the testing process. The test cases are selected according to several criteria, including the most often used functions, the rate at which features fail, and the business effects of certain features.

For example, in an ecommerce app, some of the most important features are the shopping cart and the checkout process, so it’s important to verify that they always work. Regression tests in these areas should be given priority and executed often.

In addition to important features, you should include test cases involving recently added features and frequently used functions because these are the areas where bugs are most likely to be found.

Retesting everything

This technique is different from retesting a particular previously failing scenario. Retesting everything is a regression testing approach that consists of executing all existing project test cases during each regression iteration. This can mean after a new deployment, at the end of a sprint cycle, or before an important release.

This is the safest testing technique, though it is very time-consuming and inefficient, especially if the tests are performed manually. Despite the costs, though, this technique proves beneficial in specific situations. For instance, it is suitable for smaller applications with limited functionality and a modest number of test cases. Additionally, re-executing all tests is advisable when there is an application-wide update, such as a significant upgrade to the operating system or modifications to accommodate a new platform or programming language.

Test case selection

Using this method, you narrow down the important components that the changes might impact and focus the regression testing exclusively on those segments. By applying a select number of relevant test cases to the appropriate sections, regression testing can be completed more efficiently and with less effort. This means that only the impacted areas of the application will be tested, while the unchanged functionalities will be left out of the current regression iteration.

This method works well for larger, complex applications that require a high volume of test script executions or in situations where QA resources are limited. It helps reduce the risk of unwanted bugs and broken features while limiting the scope of regression testing to key areas and functions. Tools like Qualiti can empower teams to take this approach by using the test plans’ functionality and grouping the tests by importance or by functionalities within test folders.

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Benefits of automated regression testing

Regression testing is a repetitive task by nature, which makes it the perfect choice for test automation. The initial investment may take more time than it would to perform the testing manually, but the return usually more than makes up for it.

Here are the most important benefits of automating regression testing.

Increased efficiency

Regression test case creation takes a lot of effort and expertise. Writing new test cases for every regression testing cycle is inefficient, especially when frequently releasing new product versions. Reusing test cases via automated regression testing will help you maximize the return on your investment and make the best use of your time. Automated testing consistently enhances test coverage by allowing for the repeated execution of all existing test scripts during each run.

Efficient scaling

In large projects, the regression test suite tends to expand significantly. Manually executing all test cases within such extensive suites is time-consuming and presents a dilemma: either allocate substantial time for comprehensive regression testing or risk incomplete coverage by executing only a subset of the suite.

Automation effectively resolves this challenge. Automated testing enables the execution of a significantly higher volume of tests per hour than manual methods. Additionally, it supports running tests continuously through the night and in parallel, dramatically increasing testing efficiency and coverage without the need for manual intervention.

Error reduction

Repetitive tasks are susceptible to human error. Continuously executing the same tests can lead to boredom, reducing attention to detail and increasing the likelihood of overlooking critical issues. Automation offers a solution by ensuring consistent and precise test execution every time, enhancing the reliability of defect detection.

Automating routine testing also frees up time for manual activities that require human insight, such as exploratory testing, thereby improving overall testing quality.

How to automate regression testing

When starting to implement automation for regression testing in a project, there are several initial steps to take.

Identify the test cases

This step requires identifying the components of an application that require regression testing and understanding the extent of changes introduced with each release. Based on this information, teams can strategically select the test cases for automation. Begin by automating the most frequently executed tests during the manual regression and gradually proceed to the least frequent ones.

Find the right tool

Selecting the appropriate tool for creating your test scripts should be based on the specific tests you plan to automate, the technical expertise of your testing team, and your budget constraints. Selenium WebDriver is a common tool for UI web testing, and Appium is a popular choice for mobile testing.

Consider using low-code or no-code automation tools if you prefer not to code the tests manually. These tools typically record the application’s steps and replay them with each execution. It’s essential to choose an automation tool that simplifies the testing process and provides robust reporting features. Some good options here include Qualiti or Selenium IDE.

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Create the test scripts

A critical and challenging aspect of setting up an automated regression test suite is creating the test scripts. Automated test scripts should be easy to read and maintain while not being dependent on each other. A good automated test script should ideally focus on a single validation (e.g., validate that the login is done correctly) and should always give the same result. This means making sure that each test leaves the application in the state it was before the test execution.  

Be sure to carefully select the most pertinent test scripts and ensure that they are regularly updated whenever new code is integrated into the final product.

Here is a sample login test written in JavaScript using Puppeteer:

// addName.test.js
const puppeteer = require('puppeteer');
describe('Login Test', () => {
  let browser;
  let page;
  beforeAll(async () => {
    browser = await puppeteer.launch();
    page = await browser.newPage();
  });
  afterAll(async () => {
    await browser.close();
  });


  it('should login with valid credentials', async () => {
    await page.goto('https://demoqa.com/text-box');
    await page.type('#userName', 'your-username');
    await page.click('#submit');
    const value = await page.$eval('#name', el => el.value);
        expect(value).toBe('Name:your-username');
  });
});

This script sets up a browser instance using Puppeteer, navigates to the login page of your web app, fills in the login form, submits it, and checks if the navigation after login is to the expected URL. Here’s what the functions do:

• beforeAll: Sets up the browser and page before running the tests
• afterAll: Closes the browser after running the tests
• it('should login with valid credentials'): The test case that performs the login and checks the resulting URL

Execute the automated tests

Once the test suite is finalized, you can begin executing the tests. Integrating the regression suite into a CI/CD pipeline is advisable to ensure that tests are automatically triggered following each new application release or at predetermined intervals. This integration facilitates continuous testing and delivery, enhancing the efficiency of the development process.

Analyze the results

Running tests is futile without reviewing the outcomes: examining test results for failures and investigating their causes. Failures may stem from new defects introduced by recent code changes or necessary test updates due to expected changes.

If a failure is detected due to a new defect, it must be promptly reported and remedied to maintain software quality. This is easily done using CI/CD tools such as GitHub or Gitlab, where the test results are automatically reported after the test execution is completed.

Automated testing best practices

Perform risk assessments

When designing the regression testing suite, identify potential risks associated with code changes and assess how any regression issues could impact system stability and the user experience.

Prioritize testing functionalities based on their risk level and potential influence on the application. Concentrate on high-impact or critical features to ensure thorough validation and minimize the likelihood of significant errors.

Select the right test cases

Assess which tests are suitable for automation, given that achieving 100% automation is often not feasible. Focus on automating critical and repetitive test cases to maximize coverage and efficiency. Collaborate with your team to establish clear criteria for determining which tests should be automated and which require manual intervention.

Prioritize the automation of test cases based on identified risks, their potential impact on user experience, and their frequency of use in real-world scenarios.

Perform test maintenance

Frequently updating your test suite to align with your program’s evolution ensures that your regression tests remain relevant and effective. Employ testing methods that demand minimal maintenance to reduce the burden of ongoing test management. This can be done by resetting the test environments and making sure that reused data is not affected.

Integrate regression testing in a CI/CD pipeline

Rapid test feedback can accelerate the development process. Integrating automated regression testing into a CI/CD pipeline allows the development team to quickly receive feedback on new code iterations, ensuring that any defects are identified and addressed before progressing further in the pipeline.

Shown below is an example GitHub Actions workflow that runs an automated regression testing suite on changes to a code repository. Integrating regression tests in CI/CD pipelines in this manner helps catch issues in real time as code changes are made and before they surface to end users.

# Example GitHub Actions workflow to run Jest tests
name: Automated Regression Tests
on: push
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Set up Node.js
        uses: actions/setup-node@v2
        with:
          node-version: '14'
      - run: npm install
      - run: npm test

AI tools for regression testing

AI testing tools have several advantages over traditional test automation frameworks for software testing, including automated test generation, anomaly detection, and advanced analytics. Teams turn to AI-powered tools in order to:

• Streamline testing processes and increase efficiency
• Reduce necessary test maintenance efforts
• Improve test coverage
• Mitigate the frequency of flaky or unstable tests
• Accelerate the overall software development lifecycle

Test script creation

One of the most complex tasks of automating tests is creating the test scripts. With AI tools like Qualiti, scripts are generated by observing user activity and generating user journeys. This means very little human work because the test cases are automatically identified based on the most used real-life scenarios.

Test maintenance

After each change to the application under test, the corresponding test scripts need to be maintained so that they match the new system updates. These changes can be related to new functionalities or can be small changes such as changed locators (web element IDs, CSS selectors, or XPaths).

Keeping up with all these changes can be tedious, but AI can help with adjusting the test case to match the new locators automatically.

AI can also help identify new features and how they fit in end-users’ flows, and it can modify existing test scripts or create new ones based on these flows.

Anomaly detection

AI tools can detect anomalies by analyzing the test results, helping the development team identify potential defects in the software. AI algorithms can analyze large amounts of data, including logs, metrics, and performance statistics, and find patterns or anomalies.

Using this automated process, the testing team saves time and effort. AI can learn from historical data and correlate anomalies between multiple test runs.

Continuous performance and behavior monitoring helps identify defects before they impact end-users, leading to improved software quality and better customer experience.

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Managing test results

To efficiently manage test results, they need to be organized, analyzed, and presented visually to quickly identify trends and issues. It helps to have adequate visualization, such as dashboards, charts, and screenshots, to analyze test results and distinguish between successful and unsuccessful tests.

For tests generated by AI, the capability to see exactly what is being tested is key. Team members are more confident in AI's capacity to thoroughly test the system when QA engineers and non-technical stakeholders can see these tests.

With Qualiti, testers can drill down and see each test step to understand what each automated test does, as shown below.

Last thoughts

Regression testing is a method that verifies that existing capabilities continue to perform correctly after modifications like new features or bug fixes. Due to its repetitive nature, automating regression testing can enhance its effectiveness. Automation not only diminishes the likelihood of overlooking issues but also boosts productivity, expands test coverage, and strengthens overall confidence in the software.

Using the proper tool for automated regression testing is one of the most important aspects of the process. No-code tools like Qualiti can make your work easier by handling the hardest tasks, such as creating test scripts, maintaining test data, implementing CI/CD integration, and reporting.