
β Mastering Decision Table Testing:-
“Boost software quality with Decision Table Testing techniques”
“Effective Login screen testing using Decision Tables”
“Master QA strategy with Decision Table Testing examples”
β What is Decision Table Testing?
Decision Table Testing is a black-box test design technique used in software testing to represent different combinations of inputs and their corresponding system behavior. This technique presents conditions and outcomes in a tabular format, helping testers ensure full test coverage by systematically evaluating all possible input combinations.
This method is often referred to as a Cause-Effect Table, where:
- Cause = input conditions
- Effect = system outputs
π§ Why Use Decision Table Testing?
Decision Table Testing is especially useful in systems where the output depends on multiple input conditions. It is highly effective when dealing with:
- Complex business logic
- Rule-driven scenarios
- Systems where missing a condition could lead to serious issues
By laying out inputs and their expected results, testers can verify all combinations and detect any missing or redundant test cases.
π Structure of a Decision Table:-
A typical decision table includes the following components:
Conditions | Rule 1 | Rule 2 | Rule 3 | Rule 4 |
---|---|---|---|---|
Input 1 | T | T | F | F |
Input 2 | F | T | F | T |
Output | X | Y | Z | W |
- T = True (valid input)
- F = False (invalid input)
- Outputs vary based on business logic
π§Ύ Example 1: Decision Table for Login Screen:-
Letβs consider a basic login screen with the following rules:
- If both username and password are correct, the user logs in successfully.
- If either or both inputs are incorrect, an error message is shown.
β Conditions and Rules Table:
Conditions | Rule 1 | Rule 2 | Rule 3 | Rule 4 |
---|---|---|---|---|
Username (T/F) | F | T | F | T |
Password (T/F) | F | F | T | T |
Output (E/H) | E | E | E | H |
- E = Error message
- H = Home screen
π Interpretation of Each Case:
- Rule 1: Both username and password are wrong β Show error
- Rule 2: Username is correct, password is wrong β Show error
- Rule 3: Username is wrong, password is correct β Show error
- Rule 4: Both are correct β Navigate to homepage
π§ͺ Test Case Derivation:
Positive Scenario:
- Correct username and correct password β Expect: Navigate to homepage
Negative Scenarios (Any one is enough for coverage):
- Incorrect username and password β Expect: Error message
- Correct username, incorrect password β Expect: Error message
- Incorrect username, correct password β Expect: Error message
π Example 2: Decision Table for Upload Screen:
Now, letβs look at an upload screen where the user uploads a photo. The validation rules are:
- Only .jpg format is allowed
- File size must be less than 32KB
- Image resolution must be 137×177 pixels
β Conditions and Rules Table:
Conditions | Rule 1 | Rule 2 | Rule 3 | Rule 4 | Rule 5 | Rule 6 | Rule 7 | Rule 8 |
---|---|---|---|---|---|---|---|---|
Format is .jpg (T/F) | T | T | T | T | F | F | F | F |
File size < 32KB (T/F) | T | T | F | F | T | T | F | F |
Resolution is 137×177 (T/F) | T | F | T | F | T | F | T | F |
Output (A/R) | A | R | R | R | R | R | R | R |
- A = Accept upload
- R = Reject with error message
π Interpretation of Each Case:
- Rule 1: All conditions met β Accept upload
- Rules 2 to 8: One or more conditions failed β Reject upload
π§ͺ Test Case Derivation:
Positive Test Case:
- Upload a
.jpg
image with file size < 32KB and resolution 137×177 β Expect: Image accepted
Negative Test Cases:
- Format not
.jpg
β Expect: Error - Size β₯ 32KB β Expect: Error
- Resolution incorrect β Expect: Error
- Any combination of invalid inputs β Expect: Error
β Key Benefits of Decision Table Testing:
- Improved Test Coverage: All possible input combinations are considered
- Clarity: Test conditions and expected outcomes are clearly documented
- Error Detection: Easily identify missing or redundant rules
- Efficiency: Helps reduce the number of test cases by combining similar ones
- Automation-Friendly: Can be converted into automated scripts
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π§Ύ Conclusion:-
Decision Table Testing is a powerful and efficient technique that helps testers handle complex business logic by converting requirements into structured test cases. Whether you’re working on a simple login screen or an upload feature with multiple validations, decision tables ensure all possible scenarios are considered.
Using this method, QA professionals can produce accurate, maintainable, and reusable test cases that improve software quality and reduce bugs in production.