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i need help for developaing the test cases for the following program.........i am a beginer to testing

Program Specification

The program reads three integer values from a file. The three values are interpreted as representing the lengths of the sides of a triangle. The program prints a message that states whether the triangle is scalene (all sides are different lengths), isosceles (two sides are the same length), or equilateral (all three sides are the same length).

Note that the three side lengths must make a valid triangle, e.g. 4, 4 and 6 make a valid isosceles triangle whereas 1, 1 and 6 do not (see diagrams below).

Exercise 1

Design a set of test cases that you feel would adequately test this program. Include anything that you would consider if this were a “real” (important) application and write the tests so that someone else could run them (use a separate sheet or the back of this one).