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Black box testing

The ability to quickly deliver innovative software is no longer just a technical challenge – it’s now a business imperative. Software testing is critical to accelerated development timelines, enabling DevOps teams to produce higher quality software faster. Yet, as developers examine their own code, they bring their own biases to each test, frequently limiting their ability to see software from a user’s perspective or testing the application in unexpected ways. That’s where black box testing can deliver real value.

What is black box testing?

Black box testing is a category of testing techniques that examine software applications from the outside, without any knowledge of the design or structure of a software system. Black box tests can happen at a variety of levels, from unit testing that examines the functionality of bits of code to integration testing, system testing, or acceptance testing. In a black box test, testers examine inputs and outputs to make sure an application operates as it’s supposed to, and to discover any errors that should be fixed.

Black box testing may reveal:

  • Functions of the software that aren’t working properly
  • Errors that occur when accessing databases
  • Issues with performance, application behavior, or ability to scale
  • Problems with the user interface
  • Errors that happen as particular functions are starting or ending

Benefits and limitations of black box testing

Benefits of black box testing

  • Objectivity. In a black box test, the tester is completely separated from the developer who created the code, providing critical distance and ensuring that testers use and test the application in ways the developers had not considered.
  • User-focused. Testing teams must view the software from the perspective of an actual user, ensuring that the software is more responsive to the needs of users.
  • End-to-end testing. Because a black box test looks at all relevant aspects of a software system from a user’s perspective, tests are better able to determine the end-to-end functionality of elements such as databases, dependencies, user interface, user experience, web servers, application servers, and integrated systems.
  • No technical knowledge required. Black box testers don’t need specific technical knowledge, programming skills, or IT backgrounds. For this reason, tests can be easily outsourced or crowdsourced.

Limitations of black box testing

  • Test coverage. It’s impossible for black box testers to completely test everything in large and complex projects. In contrast, white box testing allows testing teams to focus their limited time and resources on areas that are most likely to have issues.
  • Overlapping effort. A black box approach may repeat tests that have already been performed by developers.
  • Challenges designing test cases. With limited testing time, it’s harder for testers to identify all potential inputs, making it more difficult and time-consuming to write test cases.

Types of tests and techniques

Types of black box testing

  • Functional testing examines inputs and expected outputs of different functions of an application to ensure that the outputs are consistent with the requirements and specifications of the software. Typical functional tests include sanity checks, integration tests, and system tests.
  • Non-functional testing may examine the usability of an application or its performance under stress. Non-functional tests also check compatibility with other systems and test the application’s ability to scale.
  • Regression testing examines an application to see whether changes, updates, or upgrades have altered the existing functional and non-functional capabilities of the software.

Black box techniques

  • Equivalence class partitioning divides input values into different classes or groups based on the similarity of outcomes. This technique helps to improve test coverage while reducing rework and time spent.
  • Boundary value testing looks for errors in input values that may range from both ends of a boundary, where applications typically have more issues.
  • State transition testing is a technique that examines the performance of the system under different or changing states.
  • All-pairs testing combines pairs of data input to look for bugs and parameters.
  • Decision table testing uses different input combinations to examine the behavior of the system, capturing data in a table.

How black box testing is performed

Steps involved in a black box test include:

  • Determining requirements. Identify the system requirements and specifications to determine what elements can be tested.
  • Planning tests. Determine what kinds of tests will reveal how well the software meets requirements, and decide how success will be measured.
  • Analyzing test conditions. Specify the ideal conditions for each test.
  • Designing formal rules. Identify the rules for each test.
  • Creating test cases. Develop test cases to cover a maximum range of inputs.
  • Executing tests. Run tests and log results and defects.
  • Reporting results. Produce formal reports to complete the testing cycle.

Black box testing with Tricentis

Tricentis products offer the ability to automate functional testing, regression testing, and non-functional testing, as well as orchestrate these tests with scalable test management, which supports black box testing as well as manual, exploratory, and automated testing with any tool. Providing centralized control and visibility throughout the software development lifecycle, Tricentis allows QA and development teams to approach testing more strategically and collaboratively, leading to faster and higher-quality software releases.

Tricentis offers automated software testing solutions and test management tools that support continuous integration and a wide variety of testing methodologies, including data integrity testing, app-native testing, performance testing, and chaos engineering.

FAQs

What is black box testing?
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Black box testing is a type of software test that assesses the performance and reliability of a system from the outside – the tester has no knowledge of the internal structure or design of the system. In other words, the system is a “black box”, allowing the tester to only observe inputs and outputs and see how they compare to the requirements and specifications of the software.

What is black box vs. white box testing?
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While black box testing is conducted without knowledge of a system’s internal workings, white box testing allows testers to understand how a system functions. Many development organizations use both black box and white box testing to achieve greater test coverage.

What are the benefits of black box testing?
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Black box testing examines an application from the perspective of a user, resulting in software that better serves the needs and wants of users. Because black box testers have no knowledge of the application, they’ll inevitably use it and test it in different ways than development teams will, finding issues that developers may miss.

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