What are different rules of thumb to write good test cases?

Writing good and effective test cases requires great skills since after all effective testing is achieved by effective test cases only!

Writing such test cases is a great skill in itself and can only be achieved by in depth knowledge of the software system or application on which the tests are being carried out and it also requires some experience.

Here I’m going to share some rules of thumb to write effective test cases, basic test cases definition and test case procedures.

What is a test case actually?
A typical test case is comprised of components that are meant to describe an action or event, input and an expected outcome in order to determine whether the software system or application is working as it is meant to or not.

Before writing a test case you should know the 4 levels or categories of the test cases to avoid their duplication.
The levels have been discussed below:

Level 1:
This level involves writing of basic test cases using the available specifications and requirements and documentation provided by the client.

Level 2:
This level is the practical stage and it involves writing of test cases based on the actual system flow and functional routines of the software system or application.

Level 3:
This level involves grouping of some particular test cases. Some test cases are grouped together and a test procedure is written. A test procedure can have maximum up to 10 test cases.

Level 4:
This level involves the automation of the project. This leads to minimization of the human’s interaction with software system or application. This is done basically to maximize the focus upon the currently updated functionality to be tested rather than focusing on regression testing.

Following this whole pattern you can have an automated testing suite from no testable item, i.e., you can observe a systematic growth.
- The tester should know the objective of each and every particular test case.
- The basic objective of all the test cases is to validate the testing coverage of the software system or application.
- You need to strictly follow test cases standards. Writing test cases reduces the chances of following an ad- hoc approach.

Below given is a basic test case format:
- Test case id
- Units to be tested
- Assumptions
- Input /test data
- Execution steps
- Expected outcome
- Actual outcome
- Success or failure
- Observation
- Comments

You need to write a test case statement also. So here’s the basic format:

- Verify:
This is the first word of the test case statement.
- Using tool names, tag names, dialogues etc: this is basically to identify what is being tested.
- Verification with conditions.
- Verification to result.

For any kind of testing:

- You will cover all types of tests like functional test cases, negative value test cases and boundary value test cases.
- Be careful while writing the test cases.
- Keep it simple and easy to understand.
- Don’t write test case statements with the length of an essay.
- Keep it brief and to the point.
- Follow the test cases and test case statements formats stated above.
- Generally spreadsheets are used to write test cases which make them more presentable and easy to understand.
- You can use tools like “test director” when you want to automate the test cases.
- Writing clear and concise test cases forms an important part of software quality assurance.
- Also be careful that a good number of test cases cover functional testing which means that the primary focus is on how the feature works.