Test Case Writing Process and Test Data Generation

Let's start with; What is Test Data?

This is documented Data that is basically used to test the software program.

Test Data is divided into 2 sub categories

Positive Data - data which is generally given to the system to generate expected results.

Negative Data - data which is used to test exceptional, unexpected and extreme conditions.

Example to test the following code - 'z=x+y'.

Positive data: x = 3, y = 4

Negative Data: x = -9, y = 0.000000000004

Guidelines for Test Data creation

Certain guidelines are followed worldwide for test data generation. It is important to follow these guidelines in order to test the complete product functionality:

1. No data: Run your Test Cases on blank or default data. See if proper error messages are generated.

2. Valid data set: Create it to check if the application is functioning as per requirements and valid input data is properly saved in database or files.

3. Invalid data set: Prepare invalid data set to check application behaviour for negative values, alphanumeric string inputs.

4. Illegal data format: Make one data set of illegal data format. The system should not accept data in invalid or illegal format. Also, check proper error messages are generated.

5. Boundary Condition dataset: Dataset containing out of range data. Identify application boundary cases and prepare a data set that will cover lower as well as upper boundary conditions.

6. The dataset for performance, load and stress testing: This data set should be large in volume. This way, creating separate datasets for each Test Condition will ensure complete test coverage.

4 Levels of Test Case Writing

1. In the first level, basic Test Cases based upon information provided in user documentation and specification sheets are written.
2. In the second level, Test Cases based upon the functional and system of the software/application are written.
3. In the third level, small Test Cases are added to create a single Test Case that covers all of them.
4. In the fourth level, the project is automated and focuses on testing the updated functionalities and regression testing.

Important factors involved in writing Test Cases

• Whenever requirements alter or changes, Test Cases should be revised and updated accordingly
• Test Cases can be distributed among the testers as they will be assigned some categories
• A single Test Case may contribute to several Test Conditions and a single Test Condition may consist of multiple Test Cases
• Test Cases can be interdependent on each other, and this tendency is more visible when checked for medium to large applications with a bit of complex logic
• Test Cases are distributed among the developers as they are directly used by them in order to build their logic and cover all the required scenarios

How to write Test Cases?

• Test Cases should be kept neither too simple nor too complex
• After the proper documentation of the Test Cases, review it from the Tester’s point of view
• Let the testers decide the test data item values but never let them choose the test data items by themselves
• As a QA member, try not to hesitate while giving any suggestion if it can improve something
• Never forget the end user at any stage of Test Cases writing