Cause Effect Graph-
- Cause Effect Graph is a popular black box testing technique.
- It illustrates the relationship between a given outcome and all the factors that influence the outcome graphically.
Here,
- A “Cause” stands for a distinct input condition that fetches about an internal change in the system.
- An “Effect” represents an output condition, a system state that results from a combination of causes.
Applications-
- For analyzing the existing problem so that corrective actions can be taken at the earliest.
- For relating the interactions of the system with the factors affecting a particular process.
- For identifying the possible root causes, reasons for a particular effect, problem or outcome.
Advantages-
- It helps to determine the root causes of a problem or quality.
- It indicates possible causes of variation in a process.
- It identifies those areas where data should be collected for further study.
- It utilizes the team knowledge of the process by encouraging team participation.
Steps For Drawing Cause Effect Diagram-
The following steps are followed-
- Identify and describe the input conditions (causes) and actions (effect).
- Build up a cause-effect graph.
- Convert cause-effect graph into a decision table.
- Convert decision table rules to test cases where each column of the decision table represents a test case.
PRACTICE PROBLEMS BASED ON CAUSE-EFFECT GRAPH TECHNIQUE-
Problem-01:
Design test cases for the following problem-
If the character of the first column is ‘A’ or ‘B’ and the second column is a number, then the file is considered updated. If the first character is erroneous, then message x should be printed. If the second column is not a number, then message y should be printed.
Solution-
Step-01:
Identify and describe the input conditions (causes) and actions (effect).
The causes represented by letter “C” are as follows-
- C1 : The character in column 1 is ‘A’
- C2 : The character in column 1 is ‘B’
- C3 : The character in column 2 is a number
The effects represented by letter “e” are as follows-
- e1 : File update is made
- e2 : Message x is printed
- e3 : Message y is printed
Step-02:
Build up a cause-effect graph-
Step-03:
Convert cause-effect graph into a decision table-
| Test data | Causes | Effect | ||||
| A1 | A2 | A3 | M1 | M2 | M3 | |
| 1 | 0 | 0 | 0 | 0 | 1 | 1 |
| 2 | 0 | 0 | 1 | 0 | 1 | 0 |
| 3 | 0 | 1 | 0 | 0 | 0 | 1 |
| 4 | 0 | 1 | 1 | 1 | 0 | 0 |
| 5 | 1 | 0 | 0 | 0 | 0 | 1 |
| 6 | 1 | 0 | 1 | 1 | 0 | 0 |
Problem-02:
Why Cause Effect Graphing Technique is Better Than Any Other Black Box Testing Technique?
Solution-
- Boundary value analysis and equivalence partitioning do not explore combinations of input circumstances.
- These only consider the single input conditions.
- However, combinations of inputs may result in interesting situations.
- These situations should be tested.
- By considering all the valid combinations of equivalence classes, there will be large number of test cases.
- Many of these test cases will not be useful for revealing any new errors.
On the other hand,
- Cause Effect Graph is a technique that helps in selecting a high-yield set of test cases in a systematic way.
- It has a beneficial effect in pointing out incompleteness and ambiguities in the specifications.
To gain better understanding about Cause Effect Graph Technique,
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