What Is the Software Testing Life Cycle? A 101 Guide

The secret to building applications that users love? Test, test, and test again.

We cannot overstate how important testing is - which is exactly why you need to know the Software Testing Life Cycle (STLC) inside out if you want your application to impress.

Here's an at-a-glance guide to what the STLC involves, its key phases, and, crucially, how to optimize it for best results.

The Software Testing Life Cycle: What Is It?

If you're building an application, whether for your own business or for external clients, it's safe to say you want to guarantee it runs smoothly and safely before you launch.

The Software Testing Life Cycle (STLC) is a systematic testing approach that helps to ensure that your application meets key requirements, is defect free, and (to borrow a phrase from organization queen Marie Kondo) sparks joy for your target user base.

The STLC follows a series of phases with specific objectives. These phases remain the same for every software development project you test, providing a standardized testing approach that helps you guarantee quality with each release.

This offers several benefits for both your project and your wider business goals, including:

• Making it easy to track the progress and effectiveness of your testing efforts, thanks to a standardized process that encourages proper documentation
• Improving overall software quality, and increasing user and client satisfaction as a result - this can improve downstream metrics like revenue growth and customer retention
• Encouraging teams to design meaningful tests that address a project's specific requirements
• Reducing time and financial costs of a project by offering a tried and tested process, and by identifying defects early, when they are easier and cheaper to fix

Where does the STLC Fit in the Software Development Process?

The software development life cycle (SDLC - the acronyms are annoyingly similar) consists of six phases:

1. Planning
2. Requirements analysis and definition
3. Architecture design
4. Product development
5. Product testing and integration
6. Deployment and maintenance

Whilst your software testing itself will take place across the development and testing phases, you can start the STLC much earlier. You can begin defining your test requirements, deciding on test scope, and building test environments as soon as the requirements and application architecture are in place. This helps the cycle run as effectively as possible, and allows you to identify defects earlier in the process.

If your organization uses Agile software development methodology, you'll be doing the process above for smaller sections of the software, usually in shorter, consecutive 'sprints' - but the principle remains the same.

What are the Phases of the Software Testing Life Cycle?

There are six key phases to the software testing life cycle:

1. Requirements analysis
2. Test planning
3. Test case design
4. Test environment setup
5. Test execution
6. Test closure

Each STLC phase is designed to meet a specific purpose, and has a defined set of activities and exit criteria that you'll need to complete before moving on.

Requirements analysis/Requirements phase testing

Entrance criteria

• Your engineers know the requirements (both functional and non-functional) for the application they are building
• The architecture of the application has been finalized

Purpose
During the requirements analysis phase, your team dives into the application's requirements to identify what to test and how to test it. This provides a solid knowledge base for the following phases, in which you plan, design, and execute the tests.

Activities
Testing/QA teams should collaborate with stakeholders to understand requirements in detail and build a prioritized list of testing activities. If there's potential to automate any testing processes it should be discussed here.

As part of your requirements analysis, you should create a Requirements Traceability Matrix to map user requirements against test cases. This will help you track the success of your tests further along in the process.

Exit criteria

• You have built a Requirements Traceability Matrix
• You have agreed the scope for testing automation with all major stakeholders

Test planning

Purpose
During the test planning phase, your team gets to grips with the 'how', 'how long' and 'how much' questions that help stakeholders keep on top of timelines and budgets.

Activities
Your team agrees on your testing approach, strategy, and scope, estimates the effort/costs required, and identifies which testing tools to use.

Creating a Test Plan document ensures that all of this information is available to stakeholders from a single source of truth.

Exit criteria

• Your team has created a Test Plan, which has been understood and signed off by relevant stakeholders
• You have clear time/cost estimates for your testing strategy

Test case development

Purpose
During the test case development phase, your team builds and optimizes test cases and test scripts, so that the execution phase is as effective as possible.

Activities
Your team should identify the data they want to test, create test cases, and (if applicable) write all the automation scripts needed. You can then start the development process for test cases for individual units.

Exit criteria

• You have identified, written, and optimized your test cases and scripts
• You have identified the test data you need

Test environment setup

Purpose
During the test environment setup phase, your team identifies the conditions (hardware and software) under which you'll test your application.

Activities
Your team creates the test environment and performs a smoke test - that's a readiness check on the testing environment that ensures it's good to go.

Exit criteria

• Successful smoke test
• Your test data is set up

Test execution

Purpose
Your team tests the application according to your test plan, using the environments, scripts, and cases created in previous steps. This identifies any defects that need to be corrected before the application is shipped.

Activities
Your team executes and maintains test scripts, documents the test results, and logs any defects the tests identify in the Requirements Traceability Matrix.

Once the developers have addressed these defects, you'll retest the defect fixes and repeat as needed until all defects are closed.

Exit criteria

• All planned tests have been completed
• Defects have been logged and tracked to closure
• Your Requirements Traceability Matrix is complete

Test closure

Purpose
This is your opportunity to evaluate the testing process - what worked well and what didn't work so well - and identify some key takeaways for next time.

Activities
Your team analyzes the effectiveness of the STLC based on time, coverage, cost, and quality - then documents any key learnings and potential process improvements.

It's also a good idea to carry out a test result analysis to identify the defect distribution by type and severity. This is super useful feedback for developers, who can use it to improve their own processes.

Finally, now's the time to put together a test closure report and get it signed off by stakeholders, as an agreement that the testing stage is complete.

Exit criteria

• You have completed a test closure report and it has been signed off by all relevant stakeholders

How to Optimize Your Software Testing Life Cycle

A STLC that runs faster whilst being more effective is the dream, right? Here are a couple of ways you can achieve this

Use 'Shift Left' to Prevent Early-Stage Defects

'Shift left' is one of the fastest-growing development trends right now, thanks to its focus on defect prevention over finding and fixing bugs pre-release.

Shift left methodology emphasizes the importance of involving software testing teams in the earliest stages of the development cycle. This allows for early and continuous testing, which allows teams to fix issues early on in the process, when it is cheaper and easier to do so.

Crucially, it also involves testing teams in discussions with key stakeholders earlier, giving them a better handle on key testing requirements, and allowing them to gather feedback to optimize their test plans.

Introduce Trackable Code Quality Metrics

The best way to improve something? Measure it.

Monitoring code quality metrics allows you to take a baseline measurement for code quality, then track the success of actions designed to improve it. Higher quality code = fewer defects = less time needed to fix those defects.

The best metrics to use will depend on your team's preferences, requirements, and workflows, but the following are a great place to start:

• Reliability: the number of times a section of code fails and passes during tests
• Maintainability: how complex the code is to maintain - in general, the more lines it has, the harder it is to adapt it to new requirements.
• Performance: the code's speed at execute actions in a given timeframe

Read our full guide to testing automation metrics here

Use AI Driven Automation to Save Time

Automated testing isn't new. Over the past decade, options for automating parts of the software testing process have increased exponentially.

But did you know that most businesses are still not using software testing automation to its full potential?

In the past couple of years in particular, AI and machine learning have broadened the scope of what testing automation can do significantly - think 'test automation but in hyperdrive'.

AI tools can model real-world scenarios instantly, use machine learning to generate test cases, auto-correct element selection in tests when the UI changes, and so much more. That's hours of your engineers' time that you can reinvest back in project work.

Momentic: Your Engineers' Software Testing Cheat Code?

“Momentic makes it 3x faster for our team to write and maintain end to end tests.”
Alex Cui, CTO, GPTZero

We'd love to see if Momentic could help you optimize your software testing life cycle.

If, like Alex and his team, you're keen to save over two thirds of the time you spend on key testing processes, why not schedule a conversation with our founder, Wei-Wei Wu?