# Black Box – BVT on 3 Variables software testing

Last modified on January 7th, 2019 at 8:57 am

**Black Box – BVT on 3 Variables software testing**

Suppose we have three variable x,y, and z to test.

**The range of x:** 0 to 100

**The range of y : **20 to 60

**The range of z : **80 to 100

| X | y | z |

Min | 0 | 20 | 80 |

Min+ | 1 | 21 | 81 |

Nominal | 50 | 40 | 90 |

Max- | 99 | 59 | 99 |

Max | 100 | 60 | 100 |

**Figure:** Testing points detected in Simple Boundary Value Testing.

**Test cases:**

Total Test cases =

(Number of variables * Number of testing points without nominal ) + (1 for Nominal)

13=(3*4)+1

- There are total 3 variables X,Y and Z
- There are 4 possible values like min, min+, max- and max
- 1 is for nominal

**Logic:**

When we make test cases, we will fix the nominal value of two variables and change the values of the third variable.

For example

- We will fix nominal values of X and Y and make a combination of these values with each value of Z variable.

Fix nominal values of X and Y are 50,40, and we will compare these two values with 80,81,90,99 and 100.

- We will fix nominal values of Y and Z and will make a combination of these values with each value of X variable.

Fix nominal values of Y and Z are 40, 90, and we will make a combination of these two values with 0,1,50,99,100

- We will fix nominal values of X and Z and will make a combination of these values with each value of Y variable.

Fix nominal values of X and Z are 50, 90 , and we will make combination of these two values with 20,21,40,59,60

We can generate 13 test cases from both variables X, Y and Z

Test Case# | X,Y,Z | Test Case # | X,Y,Z | Test Case # | X,Y,Z |

1 | 50,40,80 | 2 | 50,40,81 | 3 | 50,40,90 |

4 | 50,40,99 | 5 | 50,40,100 | 6 | 0,40,90 |

7 | 1,40,90 | 8 | 99,40,90 | 9 | 100,40,90 |

10 | 50,20,90 | 11 | 50,21,90 | 12 | 50,59,90 |

13 | 50,60,90 |

**Figure:** Test cases generated in Simple Boundary Value Testing using 3 variables.