SDLC vs STLC: The Main Points of Comparison

The Software Development Life Cycle (SDLC) is a process that the teams use to produce quality software in the application. The purpose of SDLC is to meet customer expectations by a certain time by utilizing a cost-effective approach. SDLC was designed to handle complex businesses that require processing and analyzing data.

1. Plan / Gather Requirements

The first phase plans and gathers the significant requirements from different stakeholders. The stakeholders can include customers, team members, and subject matter experts (SMEs). Generally, the information is evaluated to determine what is most practical for the software project.

In addition, the risks and opportunities are discussed during this phase. All the requirements gathered are used to plan a feasible approach. A couple of approaches are:

• Technical Approach — All the expected services that will meet the stated technical scope of work (SOW)
• Operational Approach — All the steps taken for the transition from a software’s current condition to an end-result condition

2. Design Software

In the design software phase, the team moves with every requirement and creates a design document specification (DDS). The main question from the DDS perspective answers, “How are we actually going to build the software?”.

With all the approved requirements, the comprehensive software architecture defines processes and approaches for each module. Individual processes and modules represent the data flows and the communication. Usually, the DDS designer uses pseudo-code, business rules, screenshots, and diagrams (hierarchy, detailed logic, entity-relationship, business processes) to outline many different functionalities.

3. Develop Software

The development of software begins when the developer receives the design document specification (DDS). All the components are transformed from a high-level overview into the source code. The previous planning and specifications operate as a guide for implementing the required functionality.

4. Test Software

Testing of the software affirms its quality. The QA team refers to the system requirements document (SRD) or the user stories to verify each of the functionality. Therefore, in this phase, the goal is to ensure a quality product and confirm every functionality working as expected.

If a bug is discovered, then the QAs reproduce the steps, note them, and then assign them to the development team. A developer fixes the bugs and sends them back to QA. Generally, the QA tester who discovered the bug also retests and verifies that it no longer exists. Testing is performed by the QAs until the software operates according to the business requirements and customer’s standards.

5. Deploy Software

In the deployment phase, the team has already resolved all the bugs and satisfied the agreed specifications. Finally, the software is released to the production environment. It is available for the market so customers can use the software.

6. Maintain Software

The software maintenance phase is the most vital for SDLC. It safeguards the software and continues to perform as per the requirements. The team gradually transitions from developing and testing the software to maintaining the software. Based on the different feedback from the development team and the end-users/customers, the following actions are taken:

• Fix all the bugs reported by the QAs or the end-users/customers.
• Enhancing the software by adding new features.
• Upgrading to the new software versions.

The maintenance mode of the software consists of adding new code or altering existing code. The development team creates new features and deals with all the enhancement requests. QA team continues testing the software and finding bugs. Additionally, the end-users may find defects and the developers fix all the reported issues.

What Is STLC

The software testing life cycle (STLC) is a series of tasks that are performed to ensure the software meets definite quality standards. It involves analyzing the requirements of the user stories, creating test plans, designing and executing test cases, and reporting defects and test results.

The STLC phase occurs after the software is developed and before the software is released to the market. Its purpose is to make sure that there are no blocker bugs released via the development team or any critical defects caught by the end-users.

1. Analyze Requirements / User Stories

The first phase of STLC consists of analyzing requirements or user stories. Normally, it kicks off after the requirements are gathered during the SDLC process. The QA team gains adequate understanding so that the gaps in the requirements are identified and they know what all tests are necessary.

After studying all the requirements, testing priorities are selected and marked, and the scope of testing is determined for establishing a proper testing foundation. The requirements can be non-functional and/or functional. The Waterfall methodology analyzes requirements while the Agile methodology analyzes the user Stories.

2. Plan Test

A test plan is a document that outlines the main strategy for testing an application. It explains the basic objectives, processes, and the team. Some of the elements present in the test plan document include:

1. Test Objective
2. Test Assumption
3. Test Environment
4. Test Coverage
5. Test Risk
6. Test Features
7. Test Approach
8. Test Resources
9. Test Activities
10. Test Schedule

Planning the test is meaningful because it clears the vision for analyzing the requirements and transforms the insights into a strategic document. The test plan is responsible to keep the stakeholders on the same page.

3. Design Test Cases

A test case is a document that includes all the pre-conditions, test data, test steps, expected results, and the post-conditions. Before designing a test case, the QA can implement several testing techniques to increase the overall coverage of an application.

Before designing a test case, the QA can achieve deep coverage by implementing various test techniques. Some known techniques are Boundary Value Analysis (BVA), Equivalence Partitioning Testing, and Path Testing. The test cases are developed via different test scenarios that are created to validate a particular requirement. Sometimes, the test cases created are reviewed by other team members and at the appropriate time, the test cases should be updated to validate the new functionalities and the existing functionalities.

4. Execute Test Cases

In the test execution phase, the QA begins running the different scenarios of test cases based on the designed test cases. The execution walks step-by-step through the software and compares the expected and the actual results. The testers run many test cases within a certain time frame. The main objective is to sign off after testing and securing the software quality.

5. Report Bugs / Defects

Occasionally bugs are used interchangeably to describe a flaw in the software. Other times, a software development team refers to a bug being discovered internally while defects are discovered externally by customers.

Either way, it’s a discrepancy between the expected and actual results. Reporting the bugs/defects involves a process of informing stakeholders. While executing a test, the QA team observes a problem and reports the problem. That’s when the process of tracking the bug starts in the STLC 🐞

Most organizations have a tracking system where the bug/defect goes through its life cycle. The life cycle is a way of maintaining the status of the reported issue. It’s no longer an issue until a developer fixes the bug/defect and the QA team confirms the fix.

6. Report Test Results

Reporting test results is a process that includes summarizing and communicating information to stakeholders. The summary quantifies test metrics, prominent risks, etc. Some examples included in the test report are:

• Total number of executed tests
• Total number of passed tests
• Total number of failed tests
• Total number of defects
• Total number of resolved defects
• Total number of outstanding defects

Conclusion: SDLC & STLC Comparison

SDLC and STLC have phases that extend each other. For example, the SDLC encompasses gathering requirements and testing software. The STLC incorporates analyzing requirements before creating a test plan.

When it comes to setting up the test environment, this activity can be carried out in the SDLC or STLC. Although essential, the QA team is not responsible for constructing the test environment. Developers generally set it up so testers can start execution. The following is a breakdown of each phase for SDLC and STLC.

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