Multiple Condition Coverage is a white box testing technique - Explain?

There are so many types of the code coverage and the multiple condition coverage is also one of them and that is what has been discussed all about in this article.

What is code Coverage?

Code coverage as we all know is a process that aims at the following purposes:

- Creation of the additional test cases for increasing the coverage.
- Looking up for such areas of the software system or application code that have not been exercised by any of the test cases.
- Determination of the quantitative measure of the extent of the code coverage which can be thought of as an indirect measure of the software quality.
- Identification of the redundant test cases which does not affect the code coverage.

The whole process is a time consuming one and thus is helped by an automating tool called the code coverage analyzer.

What is Multiple Condition Coverage?

- Multiple condition coverage is a modification of the condition coverage type of the code coverage.

- As the term “multiple condition coverage” itself suggests that it implements almost all the possible combinations of the conditions in order to check whether those possible combinations do occur in the execution of the test cases or not.

- A large number of the test cases are required for carrying out a full multiple condition coverage of a decision and these are supplied by the truth tables of the logical operators obtained for that particular decision.

- The multiple condition coverage offers an added advantage in the languages such as C, C++, Java and so on which have short circuit operators which is that it helps in implementing a thorough testing.

- It in turn makes the multiple condition coverage in such languages very similar to the condition coverage.

Disadvantage of Multiple Condition Coverage

But, one should not think that the multiple condition coverage is void of any disadvantages.

- It does have one which is that the deciding up on the minimum number of test cases required for the coverage proves to be very difficult job.

- The problem worsens as the complexity of the boolean expressions implemented in the decisions increases.

- Another disadvantage adds to the problem of the test case designer which is that the minimum number of the test cases required for the coverage varies substantially from condition to condition having the similar level of complexity.

Lets take an example:

For example, in a decision, first condition may require 5 test cases while the second one may require 11 test cases and both the conditions are having the same number of operators and operands.

In contrast to the condition coverage that includes the decision coverage also, the multiple condition coverage does not include any decision coverage.

Now what about the languages like Pascal and visual basic that do not have short circuit operators? For such languages the multiple condition coverage is implemented in the form of the path coverage for logical expressions.

One point to be noted here is that the advantages and disadvantages remain the same in the path coverage form also since in the path coverage the number of each additional logical operator is doubled the number of the required test cases.

Multiple condition coverage takes in to consideration two or more conditions and then makes them in to a group and then they are tested. "Since the multiple condition coverage requires a very detailed knowledge of the software system or application’s code in order to understand all the decision aiming statements in that and in turn decide for the minimum requirement of the test cases, therefore it has been categorized under the white box testing techniques."

Branch Coverage or Decision Coverage in White Box Testing

Code coverage analysis is the process of finding areas of a program not exercised by a set of test cases, creating additional test cases to increase coverage, and determining a quantitative measure of code coverage, which is an indirect measure of quality.
A Decision is a program point at which the control flow has two or more alternative routes. A decision coverage is the percentage if the decision outcomes that have been exercised by a test suite.
Branch coverage testing helps in validating of all the branches in the code and making sure that no branching leads to abnormal behavior of the application. It is a better practice as compared to statement coverage. It goes deeper into the code as compared to statement coverage.
It states whether the the boolean expressions are tested in control structures. It ensures for having adequate number of test cases for every program to ensure execution of every decision or branch at least once.

What are the advantages of branch coverage?
- To validate that all the branches in the code are reached.
- To ensure that no branches lead to any abnormality of the program’s operation.
- It eliminate problems that occur with statement coverage testing.

What are disadvantages of branch coverage?
- There may be other condition that can be used for decision making.
- This metric ignores branches within boolean expressions which occur due to short-circuit operators.