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| − | ==Preliminaries==
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| − | * Make a new project with ''n'' = 7 (following [[CISC181_F2017_NewAndroidStudioProject | these ]] instructions)
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| − | * Name your main class "Lab7" (when creating a new module in the instructions above, in the ''Java class name'' field)
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| − | ==Instructions==
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| − | In this lab you will develop a public '''Fraction''' class (in <tt>Fraction.java</tt>) with the arithmetic and output functionality listed below. However, you are also required to use a [http://en.wikipedia.org/wiki/Test-driven_development#Test-driven_development_cycle "test-driven development"] approach based on unit testing. Thus, as you start to implement the methods below, you must also create a public '''FractionTests''' class (in <tt>FractionTests.java</tt>) which contains a suite of unit tests (aka methods) to test <tt>Fraction</tt> thoroughly.
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| − | ===Fraction===
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| − | <tt>Fraction</tt> must have two private ints: <tt>numerator</tt> and <tt>denominator</tt>. If any arguments to the functions below have denominators with 0 value, you must throw an <tt>IllegalArgumentException</tt>. '''<tt>Fraction</tt> should also implement the [https://docs.oracle.com/javase/7/docs/api/java/lang/Comparable.html<tt>Comparable</tt>] interface'''. Here are other the public methods that Fraction must implement:
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| − | ====Constructors====
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| − | * A two-parameter constructor that initializes the numerator and denominator
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| − | * A one-parameter constructor that takes the numerator and sets the denominator to 1
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| − | ====Operators====
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| − | * <tt>void add(Fraction F)</tt>: Add another fraction F to this one
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| − | * <tt>void subtract(Fraction F)</tt>: Subtract another fraction F from this one
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| − | * <tt>void multiply(Fraction F)</tt>: Multiply this fraction by another fraction F
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| − | * <tt>void divide(Fraction F)</tt>: Divide this fraction by another fraction F
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| − | * <tt>void pow(int n)</tt>: Raise this fraction to the ''n''th power
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| − | ====Special====
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| − | * <tt>void reduce()</tt>: Reduces numerator and denominator to [http://en.wikipedia.org/wiki/Irreducible_fraction lowest terms]. For example, "2 / 4" -> "1 / 2", or "10 / 15" -> "2 / 3". You may look up pseudocode for how to reduce factors.
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| − | * <tt>String toString()</tt>: Returns the fraction as a string, written as "numerator / denominator" -- e.g. "1 / 4", or "3 / 5". It should '''always''' be reduced first. If the numerator is 0, just return "0". If the denominator is 1, just return the numerator -- e.g. "5 / 1" -> "5". Also, handle negatives properly! E.g., -3 / -5 should be written as "3 / 5", and 1 / -2 should be written as "-1 / 2".
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| − | ===FractionTests===
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| − | <tt>FractionTests</tt> must have tests that cover every method above, with multiple "normal" and "border" cases as input, including <tt>compareTo()</tt> as implied by <tt>Fraction's</tt> implementation of the <tt>Comparable</tt> interface. You should also test that denominator = 0 exceptions are also thrown as specified. <!--If you are not using JUnit, these will cause your program to end, so you may comment them out in <tt>run()</tt> (see below) as your testing progresses.-->
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| − | Each test method should have the following form: "<tt>void xNTest() { ... }</tt>", such as "<tt>add1Test()</tt>" or "<tt>division2Test()</tt>", etc. Each test method should make at least one <tt>Fraction</tt> object, set some values, perform an operation or more, and test whether the correct output was obtained. Write comments to explain *why* each test is useful!
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| − | To declare that a test has been failed, define a new public class called <tt>FractionException</tt> derived from <tt>Exception</tt>. It should have a constructor that takes a String. Throw an instance of <tt>FractionException</tt> in test method <tt>xNTest()</tt> constructed with the message string "Failed xNTest()" IF AND ONLY IF A TEST IS FAILED.
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| − | You will be using JUnit, so simply annotate all of your test functions appropriately. There should be ''at a minimum'' 20+ tests to get decent coverage of <tt>Fraction's</tt> functionality.
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| − | ===main()===
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| − | This is what your <tt>main()</tt> should contain:
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| − | Result result = JUnitCore.runClasses(FractionTests.class);
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| − | for (Failure failure : result.getFailures())
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| − | System.out.println(failure.toString());
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| − | ==Submission==
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| − | Submit your <tt>Fraction.java</tt> and <tt>FractionTests.java</tt> on Sakai (be sure to add your name and section number to both). Do NOT submit <tt>Lab7.java</tt>.
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