CIT 597 Assignment 9: Fractions and Unit Testing
Fall 2008, David Matuszek

Purpose of this assignment:

• To get you started with unit testing in Ruby.

General idea:

Implement a Fraction class. Write tests for it.

Because this is a very short assignment, it will be worth 25 points instead of the usual 100 points.

Programming details:

Fraction

Implement a Fraction class. It should have:

• A constructor that takes two arguments (the numerator and denominator)
• The instance methods add, subtract, multiply, and divide. Each of these should take one operand, the second argument, and return a new fraction (for example, f1 = f2.add(f3))).
• A private reduce! method, which uses Euclid's algorithm to put a fraction into the lowest terms (it divides both the numerator and the denominator by the gcd, Greatest Common Divisor, of the two).
• A to_s method, for returning a string representation (for example, "2/3") of this fraction.

All fractions should automatically be kept in lowest terms. For example, if you construct a fraction with f = Fraction.new 8, 12, you will get the fraction 2/3. Likewise, if you add 1/4 and 1/4, you should get 1/2. Also, there is nothing wrong with so-called "improper" fractions (fractions greater than 1, such as 7/3); they are perfectly good fractions.

To keep this assignment simple, you don't have to worry about negative numbers.

FractionTest

Implement a FractionTest class containing unit tests for each of the four arithmetic methods, and a test for the constructor. You can test the constructor by testing, for example, whether Fraction.new 8, 12 is equal to 2/3.

Due date: