In this tutorial we will study **Black Box Testing Techniques.**

## There are 3 techniques

**1. Equivalence Partition: **

Equivalence class partitioning- equivalence class partitioning is a black box technique which can be applied to all levels of testing like unit integration system etc.

**Definition-**

In this technique, you divide the set of test condition into a partition that can be considered same.

1. It divides the input data of a software into different equivalent classes.

2. this technique is used when there is a range in input field.

In above example there are 4 partitions from which 3 are invalid partitions and 1 is valid partition.

Consider a text box which only accepts values between the range 40-80.

The values are chosen above upper limit and below lower limit along with the valid values from the range.

**Input data can be chosen as:**

- Partition 1- (0,22)
- Partition 2- (45,78)
- Partition 3- (82,120)
- Partition 4- (143,159)

Select two values from each partition.

Equivalence partition is classified into two types.

1.** Pressman technique:**

- Test the range of values by one valid value and two invalid values.
- If input is of Boolean values then we test for either true or false value.

2. **Practice technique:**

- Test the range of values by 2 invalid values and multiple valid values.
- For boolean type value test for both true and false values.

**Boundary value analysis:**

- Boundary value analysis tests only boundary values than whole range of valid values.
- If consider range (A – B) then we test the vales A-1,A,A+1,B, B-1, and B+1.

- In this technique, randomly select the values by considering requirement document.
- Values can can be valid or invalid.
- Guessing method followed to get error identify new kinds of input.