Introduction to Automated Testing

Before we can deliver our software to users, we need to ensure that it works as intended and is free of defects. Essentially, the software needs to be tested, and the most effective way to test software is via automated tests.

The benefits of automated testing

In software development, automated testing offers several benefits, contributing to the improved efficiency, reliability, and overall quality of the software. Here are some key advantages of automated testing:

• Faster and more efficient testing: Automated tests are executed much faster than manual tests, allowing us to receive quicker feedback on the software’s functionality. Automated testing tools can perform repetitive tasks, execute test cases in parallel, and generate detailed reports, saving significant time and effort compared to manual testing.

• Instant feedback: Automated tests provide instant feedback because they’re fast, efficient, and can run continuously during the development process. If our changes to the software don’t work as intended or cause an unexpected change in behavior elsewhere, we’ll find out right away, long before we deploy the whole application in the test environment.

• Early bug detection: Automated tests catch bugs early because they provide instant feedback by promptly identifying and addressing issues. Developers can thus avoid the accumulation of bugs and prevent them from spreading to other parts of the software.

• Improved test coverage: With automated testing, it becomes easier to achieve comprehensive test coverage by executing numerous test cases, including edge casesAn edge case is a scenario that is not considered normal or expected to happen often, but may still occasionally happen. and boundary conditionsIn automated testing, a boundary condition refers to the minimum or maximum input or state values that are on the edge or immediately adjacent to the valid range of values. Testing these conditions helps developers identify potential issues or vulnerabilities in the software.. This helps identify bugs and issues that might be missed in manual testing, leading to higher-quality software.

• Regression testing: Software often undergoes changes and enhancements over time. Automated tests can be rerun after each modification to ensure that the functionality remains intact. This is known as regression testing, and it reduces the chances of introducing unexpected bugs into the existing code while making changes.

• Increased test accuracy: Automated tests are precise and consistent, eliminating human errors that may occur in manual testing. This ensures that the same test steps are executed accurately every time, leading to reliable and reproducible test results.

• Scalability: Automated tests enable scalability, allowing us to execute a large number of tests across different configurations, operating systems, and platforms. This is especially useful for running software on multiple devices and in different environments.

• Cost and time savings: Although setting up and maintaining an automated testing infrastructure may require an upfront investment, it can result in long-term cost and time savings. Automated tests reduce the need for manual testing efforts, allowing testers to focus on more complex scenarios and exploratory testing.

• Continuous integration and deployment: Automated testing seamlessly integrates with continuous integration and continuous deployment (CI/CD) pipelines. Automating the testing process makes it easier to validate software changes quickly and frequently, ensuring that the software remains stable and reliable throughout the development lifecycle.

How is automated testing implemented?

Automated tests are implemented via the following stages:

1. Creating a test executable and installing a suitable test framework: Tests are done within a special-purpose executable. In .NET, it is a project. This executable contains special types of methods that represent the tests. We need to reference a testing framework within the executable to write such methods. In our case, we must reference an xUnit NuGet package within a test project.

2. Adding references to libraries that need to be tested: Automated tests allow us to test the methods in the code directly without deploying the whole application. End-to-end tests are an exception because we make calls against a deployed application. The test executable needs to reference the library in order to enable us to test methods in a particular library.

3. Defining the test cases: Once our project structure is set up, we need to decide what we’re testing, develop useful test scenarios, and include some edge cases and boundary conditions. If we design our tests well, we can ensure that we’ll test the full range of behavior that a particular piece of functionality can exhibit.

4. Write the tests: After we devise all the test scenarios, we represent them by writing tests. Once the tests are written and validated, they forever remain a part of the test suite in order to help us with regression testing. These tests are only modified or removed when the functionality under the tests is modified or removed.

There are more steps that can improve the usefulness of automated tests, such as integrating them into the CI/CD pipeline. However, the four steps above are the most crucial, especially from a software developer’s perspective.

Automated test frameworks available on .NET

Here are the three automated test frameworks available on .NET:

• xUnit

• NUnit

• MSTest

Although each framework has its advantages and disadvantages, they are all largely equivalent. Thus, choosing one over the other is mostly a matter of personal preference. All the core principles and best practices of automated testing apply to all these frameworks.