How does Static Testing Differ from Dynamic Testing?

Testing is an essential part of software development, determining the quality of the end product. However, deciding on suitable test types for your application can be challenging since there are various test types based on aspects like purpose, scope, and execution strategy.

Static and dynamic testing are the two main test types we often need to use. So, let’s discuss static and dynamic testing and their differences and similarities to understand when to use each.

What is Static Testing?

In static testing, the source code is analyzed without running the program. It focuses on identifying issues like code quality, coding standard violations, security vulnerabilities, etc. Static testing is usually done at the initial stage of the project to identify faults that are not very severe.

Features of Static Testing

• Cost-effective: helps identify issues early in the development process, reducing the cost and effort of fixing them later.
• Review-based: uses code reviews, walkthroughs, and inspections to detect issues.
• Automated tools: static code analysis tools are used to automatically identify potential errors, security vulnerabilities, and coding standard violations.
• Code quality: enhances overall code quality by enforcing coding standards and best practices.
• Security analysis: helps identify potential security issues.

What is Dynamic Testing?

Dynamic testing, on the other hand, involves executing the code and checking the software’s behavior against expected outcomes. This type of testing is performed during or after the implementation phase to validate the software’s functionality, performance, and reliability under various conditions.

Features of Dynamic Testing

• Execution-based: involves executing the software to check for proper operation and uncover defects that manifest during execution.
• Runtime behavior analysis: examines the software’s behavior during runtime, identifying issues related to performance, memory usage, and overall system stability.
• Functional verification: ensures the software meets the specified requirements and performs the intended functions correctly.
• Performance evaluation: includes performance, load, and stress testing to determine how the system behaves under various conditions and loads.
• User simulation: tests the application as it would be used in real-world scenarios, providing a user-oriented perspective.

Differences Between Static and Dynamic Testing

While both static and dynamic testing aim to improve software quality and reliability, they have different responsibilities at different stages of the SDLC. Static testing focuses on reviewing code and documentation without design work, while dynamic testing uses software to verify its behavior under different conditions.

The following comparison of their key features, followed by the summary comparison table, will help you understand the key differences between static and dynamic testing:

1. Main Focus

• Static testing is used to find problems in the code, documents, and design without running the code. This includes going through the source code, documentation, and design diagrams to identify errors, gaps, and inconsistencies through code and documentations.
• Dynamic testing focuses on the behavior of the software. This involves executing test cases, observing the system response, and ensuring the software behaves as expected.

2. Coverage

• Static testing: covers all aspects of the codebase, documentation, and design artifacts.
• Dynamic testing focuses on the execution paths and runtime behavior of the software.

3. Cost

• Static testing is usually cheaper because it is done in the early stages of development. Correcting issues at this point is cheaper than in the implementation phase of the software.
• Dynamic testing is relatively expensive since it involves creating test environments and test data and running the tests. Also, correcting the defects in the later stages will require significant effort and cost.

4. Timing

• Static testing is performed early in the development lifecycle, often during the coding and design phases.
• Dynamic testing is performed during or after the project’s implementation phase to validate the application’s actual behavior and performance.

5. Output

• Static testing provides feedback on the quality of the code, code standards, and correctness of code design. The output usually consists of lists of the detected problems, such as syntax errors, possible bugs, and inconsistencies in documentation.
• Dynamic testing provides outcomes that reveal the software’s effectiveness and efficiency. The outputs include test reports, logs of the executed test cases, performance metrics, and lists of defects identified during the test case run.

6. Tools

• Static testing uses tools like code analyzers ( SonarQube, ESLint, Checkstyle), document review tools, and version control systems
• Dynamic testing uses tools like automated testing frameworks (Selenium, JUnit), performance testing tools (LoadRunner), and debugging tools to execute test cases and validate software behavior.

Choosing Between Static and Dynamic Testing

Choosing between static and dynamic testing is not about choosing one over the other but about understanding the context in which each will be used.

Static testing is best used early in the development lifecycle for identifying code quality issues, logical flaws, and documentation gaps without executing the code. It is cost-effective and helps in the early detection of defects, reducing errors in later stages.

On the other hand, dynamic testing is suited for later stages to validate the software’s runtime behavior, performance, and user interactions. It requires more resources but is crucial for ensuring the software meets functional requirements and performs well under various conditions.

You can also combine these tests to get the best of both worlds. This will help you cover all the stages of the software development cycle, from designing to delivery, improving the overall quality of your product, and making the development process more effective.