**Branch testing** is a type of white-box testing that is used to test every possible branch in the control flow graph of a program. In branch testing, every branch in the code is executed at least once.
# Why do we need branch testing?
We need branch testing because:
* It ensures that no branch in the code leads to abnormal behavior.
* It guarantees that all branches in the code are reached.
* It is a quantitative measure of the code coverage of the program.

# How to calculate branch testing
*Branch testing* of a program is carried out by calculating a metric called **branch coverage**. Branch coverage is the ratio of the number of branches covered to the total number of branches. Branch coverage can be calculated as:


# Example
Consider the code snippet below, which is a simple program to find the maximum of two numbers:

int a = 2;
int b = 5;
if(a>b){
  cout<<"a is max";
}else{
  cout<<"b is max";
}

## Control flow graph
The control flow graph of the code above will be as follows:

## Branch testing
### Branches
The branches in the control flow graph above are A, B, C, D, E, F, and G. 



### Branch Coverage
For maximum branch coverage, we take the path:

 *Path1* = 1A-2B-3C-4D-5F-7
* *Covered branches* = A, B, C, D, F
* *Uncovered branches* = E, G

The branch coverage of *path1* will be:

*Branch coverage* = (number of branches covered / total number of branches) x 100

*Branch coverage* = (5 / 7) x 100

*Branch coverage* = 71%

Branches E and G are not covered in *path1*. To cover branches E and G, we take the path:

 *Path2* = 1A-2B-3C-4E-6G-7
* *Covered branches* = A, B, C, E, G
* *Uncovered branches* = D, F

The branch coverage of *path2* will be:

*Branch coverage* = (number of branches covered / total number of branches) x 100

*Branch coverage* = (5 / 7) x 100

*Branch coverage* = 71%

For 100% branch coverage, we combine both paths, *path1* and *path2*. The final branch testing of the control flow graph above becomes:

* *Path1* = 1A-2B-3C-4D-5F-7
* *Path2* = 1A-2B-3C-4E-6G-7




What is branch testing?

Testing every possible branch in a program ensures all branches are reached and function correctly. Coverage is measured as a ratio of branches covered.