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Unit testing

Unit testing is part of a software testing protocol where individual units of source code are tested individually. Usually performed by developers or quality assurance (QA) staff, unit testing is typically the first level of software testing and is intended to verify that the smallest components in a software program work as intended. A unit of code may be a specific function, procedure, object, method, or module. Effective unit testing can help developers find defects earlier in the development process when it is easier and less costly to fix them.

Types of unit tests

Unit tests may be automated or manual. Automated approaches are far more common as they are faster and more accurate, but some developers prefer a manual approach.

  • White box testing, in which the functional behavior of the code is tested by developers who have written it or are familiar with the code. The purpose of white box testing is to validate execution.
  • Black box testing, in which testers who are not privy to the internal functionality of the code test the user interface, inputs, and outputs.
  • Gray box testing, a combination of white and black box approaches where testers are partially aware of the functionality of the code.

Unit tests typically have three stages:

  • Preparing and reviewing the unit of code
  • Making test cases and scripts
  • Testing the code
types unit testing

Benefits of unit tests

Unit tests enable software development teams to:

  • Save time. Performing frequent unit tests will save time during regression testing.
  • Easier, faster fixes. It’s easier for developers to fix bugs in a unit of code when they are still immersed in it rather than long after they have moved on to other parts of the software, or when defects are discovered during system testing or acceptance testing.
  • Create more reusable code. Unit testing facilitates more modular code, making it easier to reuse.
  • Lower cost. The cost of fixing issues during unit testing is much less than the cost of repairing defects found during acceptance testing or when software is in production.
  • Easier debugging. With unit tests, only the latest changes need to be debugged when a test fails.
  • Higher quality code. Unit testing significantly enhances code quality and helps developers find the smallest defects before moving to integration testing.

Unit testing best practices

  • Make sure that unit tests are independent of one another. If one unit of code is changed or enhanced, unit test cases will not be affected.
  • Test one piece of code at a time. This practice will simplify code changes or refactoring.
  • Create clear and consistent naming conventions for unit tests. This will help eliminate confusion as the volume of written unit tests expands.
  • Fix bugs in each unit before proceeding to the next phase of software development. Defects found during unit testing must be fixed before moving on to integration testing.
  • Write tests that expose defects before fixing them. Before fixing a bug, it’s important to write or modify a test that will reliably expose the defect. That way your unit test can catch the defect in future iterations if it is not properly fixed.
  • Test early and often. Unit tests are best performed continuously and frequently.
  • Separate test and production code. When performing unit testing, ensure that the test code is not deployed with the source code in the build script.

Unit testing with Tricentis qTest

Tricentis qTest provides software test automation tools that help enterprises and development teams prioritize quality, develop more reliable software, and increase speed to market. qTest offers a suite of Agile testing tools designed to improve efficiency and ensure collaboration that enables teams to release the best software. With qTest, developers and testers can centrally manage open-source frameworks and commercial test automation tools for unit testing, functional testing, integration testing, exploratory testing, and many other testing protocols.

Tricentis qTest enables development teams to:

  • Create better software faster. qTest optimizes and orchestrates end-to-end quality across teams, projects, and applications to accelerate the speed of each release.
  • Scale automation. qTest centralizes test automation management and integrates with open-source and proprietary test automation tools.
  • Improve collaboration. qTest makes developer-tester alignment easier with real-time integration for testing with Jira at both the requirements and defect level.
  • Increase speed to market. qTest supports Agile methodology by allowing teams to use QA testing tools strategically, testing early and often, and getting to market faster.
benefits user tests

The Tricentis platform also includes solutions for test automation, performance testing, data integrity testing, smart impact analysis, and solutions for SAP, ServiceNow, Snowflake, Oracle, and Salesforce testing.


What is unit testing?

Unit testing is the first level of software testing. In a unit test, an individual component of code is tested to ensure that it works as intended.

What are the benefits of unit testing?

Unit testing allows developers to identify defects in code at a point in the software development lifecycle when it is easiest and least costly to fix them.

What is unit testing vs. integration testing?

Unit testing is the first level of software testing. Integration testing is the second level and is conducted after testing individual units. During integration testing, units or modules are combined to test their functionality as they work together. Integration testing is typically performed by testers rather than developers, and maintaining integration test cases is more expensive than unit testing.

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