The 6 Phases of the Software Testing Life Cycle

Testing plays a vital role in the software development life cycle, ensuring that applications are not only functional but also secure, dependable, and efficient. However, testing is not conducted all at once. Instead, it is divided into different phases, which serve a specific purpose in identifying and mitigating issues before they reach the end-users. 

In this article, we’ll explore the six main testing phases, breaking down what occurs at each phase, why it is important, and how it enhances the overall product quality. 

The role of software testing in the SDLC

The software testing life cycle (STLC) is an integral part of the software development life cycle (SDLC), ensuring that software is thoroughly tested before being released to the end-user. While SDLC covers the end-to-end process of software development, like collecting requirements for development, designing user interface and functionalities, writing code, deployment, and maintenance, the STLC focuses on planning, analysing, designing, executing, and completing the testing activities.

As a best practice, testing should be a continuous process throughout the SDLC, so each development phase is aligned with a testing phase. 

It is also essential to note that in modern software development, the phases of STLC may not be strictly followed, meaning that some phases may overlap or be merged depending on the project. 

The software testing life cycle

Now, let's break down each phase of the software testing life cycle, along with its role and significance.

1. Test planning

Test planning is the first crucial step in the software testing life cycle. It sets the foundation for subsequent testing phases. Test planning involves various important decisions in order to create a comprehensive document, which can be revisited during any subsequent test phase. Some of the key activities include: 

• Defining the test objectives and test scope to make sure that it is clear what we want to achieve and what will be tested. 
• Determining the overall test approach, including whether testing will be conducted manually, through automation, or a combination of both. When the test approach is clear, it is possible to select appropriate testing tools, identify required devices as well as platforms (operating systems, browsers), and make sure that there is a suitable number of qualified personnel.
• Conducting a risk assessment to identify and prepare for potential challenges that could disrupt the testing process. These challenges could include changing requirements, unstable builds, or resource constraints. Early risk identification allows for the development of mitigation and alternative solutions. 
• Establishing a timeline for testing activities, clearly specifying when each phase will take place. This helps to ensure that testing activities stay on track and do not fall behind the overall project schedule
• Specifying entry and exit criteria that outline the conditions required before testing can begin and the requirements that must be fulfilled before testing can be considered completed. These criteria ensure a structured testing process with clear start and end points, aligned with defined quality expectations.

Together, these steps form a test plan that outlines how software testing will be performed. It covers the goals, scope, resources, methods, and responsibilities, helping ensure the testing process is well-organized and aligned with product requirements.

2. Test analysis

The test analysis phase involves a thorough review of the test basis, such as product requirements, user stories, design documents, process flows, and any other relevant documentation. The primary focus during this phase is static testing, which allows a tester to examine the test basis in detail. 

Static testing can be performed typically in the form of a walkthrough, informal review, inspection, or peer review. The goal of the test analysis is to detect defects, requirement gaps, and ambiguities early in the process, before test design and execution. This process also helps to identify test conditions, which initially define “what to test” and serve as the foundation for developing test cases. 

In case defects, inconsistencies, or ambiguities are discovered in the test basis, such as missing requirements, unclear user stories, or logical gaps, they are typically directed to the accountable individual or team. Depending on the severity and impact, the defects may lead to revisions in the requirements and documentation. Until these defects are resolved, related test conditions or preparation of test cases may be delayed or put on hold to avoid rework or misaligned testing. Addressing defects early during test analysis helps prevent more costly issues later in the software development lifecycle. 

3. Test design

Once the test analysis is completed, the next phase is test design. During this phase, test conditions are transformed into test scenarios and, after that, into more concrete, executable test cases using various test design techniques. Test design focuses on how testing will be executed.

Most common test design techniques are divided into three main categories: 

Black-box testing

Black-box testing involves evaluation of the application’s functionality without knowing its internal code, structure, or logic - hence the name “black-box.” These techniques are typically used if there is a need to test inputs and outputs, validate the boundary limits and values, review complex business rules, and verify different system states.

The most commonly used techniques include: equivalence partitioning, boundary value analysis, decision table testing, and state transition testing.

White-box testing

White-box testing, unlike black-box techniques, involves complete access to the system's source code and internal documentation. Working with white-box techniques requires a solid knowledge of the code, along with programming or scripting skills. These techniques are often used to verify code paths, branches, and conditions, ensuring that internal logic and operations function as expected. 

The most commonly used techniques include statement testing and branch testing.

Experience-based testing

Experience-based testing techniques like the name hints rely heavily on the tester's previous experience in software testing as well as intuition and domain knowledge. Experience-based techniques are often used when requirements are incomplete or there is a time constraint. 

The most commonly used techniques include: exploratory testing, error guessing, and checklist-based testing.

4. Test implementation

During test implementation, all necessary preparations are completed before the test execution can begin. This includes finalizing the test cases and creating test data. Test cases can be grouped into test procedures, which can then be combined into larger test suites for structured execution. In order to optimize test execution, test procedures are prioritized and organized based on risk, dependencies, or business priorities. 

Another critical task in the test implementation phase is the test environment setup. Test environment simulates a real-world environment with specifically configured hardware and software, which ensures that test cases are executed under controlled and consistent conditions, making it easier to identify and reproduce findings accurately. 

5. Test execution

Test execution involves running test cases that were prepared during the implementation phase. Test suites are executed according to previously set priorities, where each test case is run according to its steps, following the comparison of actual results against the expected results. In case of a deviation, a defect is reported, including priority, summary, reproduction steps, and actual and expected results. All reported defects are analysed, prioritized, and re-tested after fixes are released to the test environment. 

6. Test completion

Test completion is the last phase in the software testing lifecycle, when all testing activities draw to a close. In this stage, the test plan is revisited to verify if the exit criteria have been met. A test summary report is then created, documenting how many test cases were executed, how many passed or failed, and summarizing the priority and status of defects discovered. After that, all test artifacts are archived, and environments are cleaned up from temporary configurations or setups. This ensures a clean baseline for future usage. 

Best practices for writing test cases

1. Simplicity: When talking about manual test cases, the key is to write them as clearly and simply as possible. It's often said that test cases should be understandable by everyone, regardless of previous experience in testing or the information technology field in general. Clear and simple manual test cases are also a good basis for automated test cases. 
2. Consistency: Maintain a consistent structure when writing test cases. This includes a unique test case ID, title, preconditions, test steps, expected result, and actual result
3. Traceability: Ensure that the test case is traceable back to requirements, use cases, or user stories. This ensures all functional requirements are tested, allowing easier impact analysis if requirements change.
4. Reusability: When the test case should be executed on different platforms or browsers, structure the test cases in a way that allows reuse across environments. 
5. Maintainability: Test cases should be written in a way that makes them easy to update, so that in case of any change, the corresponding test cases can be modified with minimal effort. 

The bottom line

Each testing phase is equally important in the software testing life cycle, from initial test planning to test execution and completion - all to catch issues early, reduce development costs, and deliver a over stable product. 

Whether these phases are followed one by one or adapted to the project's workflow, applying a structured testing approach helps to ensure a higher quality outcome and build greater confidence among users.