Static Testing – Software Testing

Static Testing is a type of Software Testing method that is performed to check the defects in software without actually executing the code of the software application. Whereas in Dynamic Testing checks, the code is executed to detect the defects. The article focuses on discussing Static Testing in detail.

What is Static Testing?

Static Testing also known as Verification testing or Non-execution testing is a type of Software Testing method that is performed in the early stage of development to avoid errors as it is easier to find sources of failures and it can be fixed easily. The errors that cannot be found using Dynamic Testing, can be easily found by Static Testing. 

1. Static can be done manually or with the help of tools to find bugs and improve the quality of the software.
2. It helps to find errors in the early stage of development which is also called the verification process.
3. It enhances maintainability and ultimately saves time and money in the long run.

Need for Static Testing

Static testing is needed whenever the following situations are encountered while testing an application or software:

1. Increased software size: Static testing is required to get free from bugs in the early stages of development as with testing activity the size of the software increases which is difficult to handle due to a reduction in the productivity of the code coverage.
2. Dynamic testing is expensive: Dynamic testing is more expensive than static testing as dynamic testing uses test cases that have been created in the initial stages and there is also a need to preserve the implementation and validation of the test cases which takes a lot of time from test engineers:
3. Dynamic testing is time-consuming: Static testing is required as dynamic testing is a time-consuming process.
4. Bugs detection at early stages: Static testing is helpful as it finds bugs at early stages, while dynamic testing finds bugs at later stages which makes it time-consuming and costly to fix the bugs.
5. Improvement of development productivity: Static testing helps to identify bugs early in the software development thus it helps to reduce the flaws during production and increase development productivity.

Objectives of Static Testing

Below are some of the objectives of static testing:

1. Decreases Flaws: Static testing will decrease the flaws in production as the bugs will be detected early in the software development.
2. Saves Time: Early detection of the bugs helps to save a lot of time, effort, and cost that will be required to fix the bugs.
3. Easy Bug Fixing: Static testing is used to identify the bugs early in software development, where it is quite easy to fix the bugs.
4. Quality Improvement: Enhance overall software quality of the software product by ensuring the compliance with the coding standards and best practices.
5. Cost Efficiency: Static testing helps to reduce the cost associated with dynamic testing by catching defects early.

Features Tested in Static Testing

Static testing involves testing the following things:

1. Unit Test Cases: It ensures test cases are complete, written in the correct manner, and follow the specified standards.
2. Business Requirements Document (BRD): It verifies that all business requirements are clearly mentioned in the documentation.
3. Use Cases: It examines the use cases so that they accurately represent user interactions with the system.
4. Prototype: It reviews the prototype to make sure that it accurately represents the main design and functionality.
5. System Requirements: It check the system requirements document for complete accuracy.
6. Test Data: It reviews the test data to ensure it is complete and covers all possible input scenarios.
7. Traceability Matrix Document: This ensures that all requirements are mapped to corresponding test cases.
8. Training Guides: It reviews training materials to make sure that they accurately reflect the system functionality and user procedures.
9. Performance Test Scripts: It examines performance test scripts to ensure they cover all critical performance aspects.

Static Testing Techniques

There are mainly two types of techniques used in Static Testing:

1. Review

In static testing, the review is a process or technique that is performed to find potential defects in the design of the software. It is a process to detect and remove errors and defects in the different supporting documents like software requirements specifications. People examine the documents and sorted out errors, redundancies, and ambiguities. Review is of four types:

1. Informal: In an informal review the creator of the documents put the contents in front of an audience and everyone gives their opinion and thus defects are identified in the early stage.
2. Walkthrough: It is basically performed by an experienced person or expert to check the defects so that there might not be problems further in the development or testing phase.
3. Peer review: Peer review means checking documents of one another to detect and fix defects. It is basically done in a team of colleagues.
4. Inspection: Inspection is basically the verification of documents by the higher authority like the verification of software requirement specifications (SRS).

2. Static Analysis

Static Analysis includes the evaluation of the code quality that is written by developers. Different tools are used to do the analysis of the code and comparison of the same with the standard. It also helps in following identification of the following defects:

1. Unused variables.
2. Dead code.
3. Infinite loops.
4. Variable with an undefined value.
5. Wrong syntax.

Static Analysis is of three types:

1. Data Flow: Data flow is related to the stream processing.
2. Control Flow: Control flow is basically how the statements or instructions are executed.
3. Cyclomatic Complexity: Cyclomatic complexity defines the number of independent paths in the control flow graph made from the code or flowchart so that a minimum number of test cases can be designed for each independent path.

How Static Testing is Performed?

Below are the steps that can be followed to perform static testing:

1. Planning: This step involves defining what needs to be tested, setting objectives, determining the scope of testing, and preparing a testing strategy. This should involve identifying the software components to be tested, developing the testing methods, and identifying the tools to be tested.
2. Prepare artifacts: In this step, necessary artifacts like source codes, design documents, requirement documents, and test cases are prepared.
3. Perform static analysis: Static analysis is conducted in this phase where the code is reviewed and analyzed for compliance with coding standards, code quality, and security issues using specialized static analysis tools without executing the code.
4. Perform code reviews: Code reviews are performed where a small team of experts systematically reviews the code and finds potential errors using various methods.
5. Report and document bugs: Bugs identified during static testing are reported and documented.
6. Analyze results: The results collected during static testing are analyzed to determine the quality of the software product.

Benefits of Static Testing

Below are some of the benefits of static testing:

1. Early defect detection: Static testing helps in early defect detection when they are most easy and cost-effective to fix.
2. Prevention of common issues: Static testing helps to fix common issues like syntax errors, null pointer exceptions, etc. Addressing these issues early in development helps the teams to avoid problems later.
3. Improved code quality: Static testing helps to make sure that the code is easy to maintain and well-structured. This leads to a higher quality code.
4. Reduced costs: Early bug detection in static testing helps to fix them early in the development thus saving time, effort, and cost.
5. Immediate feedback: Static testing provides immediate evaluation and feedback on the software during each phase while developing the software product.
6. Helps to find exact bug location: Static testing helps to find the exact bug location as compared to dynamic testing.

Limitations of Static Testing

Below are some of the limitations of static testing:

1. Detect Some Issues: Static testing may not uncover all issues that could arise during runtime. Some defects may appear only during dynamic testing when the software runs.
2. Depends on the Reviewer’s Skills: The effectiveness of static testing depends on the reviewer’s skills, experience, and knowledge.
3. Time-consuming: Static testing can be time-consuming when working on large and complex projects.
4. No Runtime Environment: It is conducted without executing the code. This means it cannot detect runtime errors such as memory leaks, performance issues, etc.
5. Prone to Human Error: Static testing is prone to human error due to manual reviews and inspections techniques being used.

Best Practices for Static Testing

Below are some of the best practices for static testing:

1. Define Clear Objectives: Establish the objectives and scope of static testing early in the project.
2. Develop Checklist: Create a checklist for reviews and coding standards that align with the industry best practices and specific project requirements.
3. Focus on High-Risk Areas: Prioritize static testing on high-risk areas of the codebase that are more likely to contain defects.
4. Team Training: Provide training to the team members on static testing techniques, tools, and best practices. Ensure everyone understands how to perform static testing.
5. Prevent Test Execution Delays: Time and cost can be managed and reduced if the test execution can be delayed.
6. Track Review Activities: It is good to plan the review activities and track them as walkthroughs and reviews are usually merged into peer reviews.
7. Keep Process Formal: For efficient static testing, it is very important to keep the process and project culture formal.
8. Regular Tool Updates: Keep static testing tools up to date to ensure they can effectively detect the new types of issues.

Static Testing Tools

Some of the most commonly used static testing tools are:

1. Checkstyle

Checkstyle is a static analysis tool that helps developers to write Java code and automates the process of checking Java code.

Features:

• It can verify the code layout and formatting issues.
• It can help to identify the method design problems and class design problems.
• It is a highly configured tool that can support almost any coding standard like Google Java Style, and Sun code conventions.

2. Soot

Soot is a Java optimization framework that has several analysis and transformation tools.

Features:

• It can detect unnecessary code and thus improve the overall code quality.
• It is a framework for analyzing and transforming Java and Android applications to test aspects like named modules and modular jar files, automatic modules, exploded modules, etc.

3. SourceMeter

SourceMeter is a static testing tool for static source code analysis of various programming languages like C/ C++, Java, C#, Python, and RPG Projects.

Features:

• It helps in the easy identification of vulnerable spots of the system under development from the source code.
• It can analyze code in multiple programming languages and generates reports that help developers to make informed decisions.
• The output of analysis and quality of analyzed source code can be used to enhance the product.

4. Lint

Lint is a static analysis tool that scans code to flag programming errors and bugs.

Features:

• It helps enforce coding standards and prevent errors and bugs in the code.
• It helps to identify and correct common code mistakes without having to run the application.

5. SonarQube

SonarQube is a static testing open-source tool to inspect code quality continuously.

Features:

• It analyses and identifies the technical debt, bugs, and vulnerabilities across different programming languages.
• It provides support for 29 languages and analyzes the quality of all the languages in your projects.
• It has features like custom rules, integration with code repositories, detailed code reports, and extensible plugins.

Conclusion

Static testing is an important component of the software development lifecycle. It offers numerous benefits such as early defect detection, improved quality, reduced costs, and many more. By examining the code and documentation and without executing the code, static testing helps to identify the issues at an early stage.