SDLC stands for Software Development Life Cycle. It describes the various phases involved in the software development process. The different phases of Software Development Life Cycle are-
- Requirement Gathering
- Designing
- Coding/Implementation
- Testing
- Deployment
- Maintenance
Whereas, Software testing life cycle or STLC refers to all these activities performed during the testing of a software product. The different phases of Software Testing Life Cycle are-
- Requirement Analysis
- Test Planning
- Test Analysis and Design
- Test Case Development
- Test Environment Setup
- Test Execution
- Exit Criteria Evaluation and Reporting
- Test Closure
Let us consider the following points and thereby, compare STLC and SDLC.
- STLC is part of SDLC. It can be said that STLC is a subset of the SDLC set.
- STLC is limited to the testing phase where quality of software or product ensures. SDLC has a vast and vital role in complete development of a software or product.
- However, STLC is a very important phase of SDLC and the final product or the software cannot be released without passing through the STLC process.
- STLC is also a part of the post-release/ update cycle, the maintenance phase of SDLC where known defects get fixed or a new functionality is added to the software.
As we know that development and testing are carried out parallelly. So, now let’s see the mapping between the phases of SDLC and STLC.
The following table lists down the factors of comparison between SDLC and STLC based on their phases–
| Phase | SDLC | STLC |
| Requirement Gathering | Business Analyst gathers i requirements. Development team analyzes the requirements. After high level, the development team starts analyzing from the architecture and the design perspective. | Testing team reviews and analyzes the SRD document. identifies the testing requirements – Scope, Verification and Validation key points. Reviews the requirements for logical and functional relationships among various modules. This helps in the identification of gaps at an early stage. |
| Design | The architecture of SDLC helps develop a low-level and high level design of the software based on the requirements. Business Analyst works on the mocker of UI design. Once the design is completed, it is signed off by the stakeholders. | In STLC ,either the Test Architect of Test Lead usually plan the best Strategy. Identifies the testing points. Resource allocation and timelines are finalized here. |
| Development | Development team starts developing the software. Integrate with different systems. Once all integration is done, a ready to test software or product is provided. | Testing team writes the test scenarios to validate the quality of the product. Detailed test cases are written for all modules along with expected behaviour. The prerequisites and the entry and exit criteria of a test module are identified here. |
| Environment Set up | Development team sets up a test environment with developed products to validate. | The Test team confirms the environment set up based on the prerequisites. Performs smoke testing to make sure the environment is stable for the product to be tested. |
| Testing | The actual testing is carried out in this phase. It includes unit testing, integration testing, system testing. defect retesting, regression testing. etc. The Development team fixes the bug reported, if any and sends it back to the tester for retesting. UAT testing performs here after getting sign off from SIT testing. | System Integration testing starts based on the test cases. Defects reported, if any, get retested and fixed. Regression testing is performed here and the product is signed off once it meets the exit criteria. |
| Deployment/Product Release | Once sign-off is received from various testing teams, the application is deployed in a prod environment for real end users. | Smoke and sanity testing in the production environment is completed here as soon as the product is deployed. Test reports and matrix preparation are done by the testing team to analyze the product. |
| Maintenance | It covers the post deployment supports, enhancement and updates if any. | In this phase, the maintenance of test cases, regression suits and automation scripts take place based on the enhancement and updates. |
