Black box testing

Black box tests focus on the input/output behavior of the component

Black-box tests do not deal with the internal aspects of the component nor with the behavior or the structure of the components

Equivalence testing

Equivalence testing is a black box testing technique that minimizes the number of test cases

Equivalence testing

The possible inputs are partitioned into equivalence classes, a test case is selected for each class

The assumption of equivalence testing is that systems usually behave in similar ways for all members of a class

Equivalence testing

Equivalence testing consists of two steps: identification of the equivalence classes selection of the test inputs

Equivalence classes

Coverage: every possible input belongs to one of the equivalence classes

Disjointedness: no input belongs to more than one equivalence class

I.e., partition

Equivalence classes

Representation: if the execution demonstrates an error when a particular member of a equivalence class is used as input, then the same error can be detected by using any other member of the class as input.

Test cases

For each equivalence class, at least two pieces of data are selected a typical input, which exercises the

common case an invalid input, which exercises the

exception handling capabilities of the component

Boundary testing

Boundary testing is a special case of equivalence testing and focuses on the conditions at the boundary of the equivalence classes

Boundary testing

The assumption behind boundary testing is that developers often overlook special cases at the boundary of the equivalence classes

E.g., Empty strings Year 2000 (millennium bug) …

Int converter (again)

A function converts a sequence of chars in an integer number. The sequence can start with a ‘-‘

(negative number). The integer number must be in the

range minint = -32768 to maxint = 32767.

The function signals an error if the sequence of chars is not allowed

The sequence must be <= 6 chars

Int converter (again)

1. Define equivalence classes, and related boundary condition

2. For each class, define at least one test case

Criterion

Input is a decimal number (well formed integer) Valid: may start with –, no characters

that are not digits Invalid: … Boundary: Starting “+”? Blanks?

Criterion

Length of string, number of characters Valid: <= 6 Invalid: > 6 Boundary: 6, 0

Criterion

Range of number in output Valid: <= maxint, >= minint Invalid: > maxint, < minint Boundary: maxint, minint

Calendar BBConsider a method that returns the number of days in a month, given the month and year. 

public class MyGregorianCalendar {public static int getNumDaysInMonth(int x, int y){

...}

The month and the year are specified as integers. By convention, 1 represents the month of January, 2 the month of February, and so on. The range of valid inputs for the year is 0 to maxInt.

1.define equivalence classes, and related boundary condition2.for each class, define at least one test case

Classes for month parameter

Three equivalence classes: months with 31 days (i.e., 1, 3, 5, 7, 8,

10, 12) months with 30 days (i.e., 4, 6, 9, 11) February, which can have 28 or 29 days

Nonpositive integers and integers larger than 12 are invalid values

Classes for year parameter

Two equivalence classes: leap years non–leap years

Negative integers are invalid values

Selected valid inputs

Additional boundary cases

Equivalence classes definition

An interval condition will have classes for Valid input within the interval Invalid input less than the minimum Invalid input greater than the maximum Valid input close the boundaries

A single value condition will have classes for: The valid value Invalid values less than the value Invalid values greater than the value

Equivalence classes definition

A discrete set condition will have classes for: Each value in the set A value not belonging to the set

A boolean value condition will have classes for: TRUE value FALSE value

Parallelogram

The function parallelogram(int x1, int x2, int x3, int x4, int y1, int y2, int y3, int y4) calculate the area of a parallelogram.

Parallelogram

Requirements area is always strictly > 0 The parallelogram should stay in the

first quadrant of the Cartesian plan

Define equivalence classes and tests

Criteria

Pair sides parallelism Pair same sides length Position (1st quadrant) Area > 0