Answers for the Testing lab

src/Average.java

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+public class Average {
+  private double sum = 0.0;
+  private int count = 0;
+
+  public void addValue(double value) {
+    sum += value;
+    count += 1;
+  }
+
+  public double getAverage() {
+    if (sum == 0 && count == 0) {
+      return 0.0;
+    }
+    else {
+      return sum/count;
+    }
+  }
+
+  public int getCount() {
+    return count;
+  }
+}

src/AverageTest.java

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+import junit.framework.TestCase;
+
+public class AverageTest extends TestCase {
+  public void testNewAverage() {
+    Average avg = new Average();
+
+    assertEquals(0, avg.getCount());
+    assertEquals(0.0, avg.getAverage(), 0.001);
+  }
+
+  public void testSingleValue() {
+    Average avg = new Average();
+
+    avg.addValue(5.5);
+
+    assertEquals(5.5, avg.getAverage(), 0.001);
+    assertEquals(1, avg.getCount());
+  }
+
+  public void testNonZeroes() {
+    Average avg = new Average();
+
+    avg.addValue(1);
+    avg.addValue(2);
+    avg.addValue(3);
+    avg.addValue(4);
+    avg.addValue(5);
+
+    assertEquals(3.0, avg.getAverage(), 0.001);
+    assertEquals(5, avg.getCount());
+  }
+
+  public void testZeroes() {
+    Average avg = new Average();
+
+    avg.addValue(-2);
+    avg.addValue(-1);
+    avg.addValue(0);
+    avg.addValue(1);
+    avg.addValue(2);
+
+    assertEquals(0.0, avg.getAverage(), 0.001);
+    assertEquals(5, avg.getCount());
+  }
+
+  public void testSameValues() {
+    Average avg = new Average();
+
+    avg.addValue(1);
+    avg.addValue(1);
+    avg.addValue(1);
+    avg.addValue(1);
+    avg.addValue(1);
+
+    assertEquals(1.0, avg.getAverage(), 0.001);
+    assertEquals(5, avg.getCount());
+  }
+}

src/LabAnswers.md

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+#####Question 1: 
+Might use the wrong type or leave the type empty. Might try to store the wrong type in an array. Might forget that indices are offset by 1.
+
+#####Question 2: 
+
+**New instance of a class:**
+
+scores = [0,0,0,0,0,0,0,0,0,0]
+
+names = null
+
+**Instance with a single mutation:** 
+
+scores = [0,0,0,0,0,1,0,0,0,0]
+
+names = ["Harry Potter"]
+
+**Instance with multiple mutations:**
+
+scores = [1,0,0,0,0,1,0,0,0,0]
+
+names = ["Mike Mulligan","Harry Potter"]
+
+#####Question 3:
+
+**Brand new instance of the class:** 
+
+min = 0.0
+
+max = 10.0
+
+**Simplest mutation possible:** 
+
+No mutator methods
+
+**What else can we do with the class:**
+
+We can ask it to return its values
+
+**Boundary conditions for the class:**
+
+min and max

src/Range.java

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+public class Range {
+  private double min = 0.0;
+  private double max = 0.0;    
+
+  public Range(double start, double stop) {
+    if (start > stop) {
+      min = stop;
+      max = start;
+    }
+    else {
+      min = start;
+      max = stop;
+    }
+  }
+
+  public boolean contains(double value) {
+    if (value < min || value > max) {
+      return false;
+    }
+    else {
+      return true;
+    }
+  }
+
+  public double getWidth() {
+    return getMax() - getMin();
+  }
+
+  public double getMin() {
+    return min;
+  }
+
+  public double getMax() {
+    return max;
+  }
+
+  public Range intersection(Range other) {
+    double newMin = 0.0;
+    double newMax = 0.0;
+
+    if (other.contains(min)) {
+      newMin = min;
+      newMax = other.getMax();
+    }
+    else if (other.contains(max)) {
+      newMin = other.getMin();
+      newMax = max;
+    }
+    return new Range(newMin, newMax);
+  }
+}

src/RangeTest.java

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+import junit.framework.TestCase;
+
+public class RangeTest extends TestCase {
+  public void testNewRange() {
+    Range rng = new Range(0.0, 0.0);
+  }
+
+  public void testMin() {
+    Range rng1 = new Range(1.0, 10.0);
+    assertEquals(1.0, rng1.getMin());
+
+    Range rng2 = new Range(15.0, 10.0);
+    assertEquals(10.0, rng2.getMin());
+  }
+
+  public void testIntersection() {
+    Range rng1 = new Range(1.0, 10.0);
+    Range rng2 = new Range(5.0, 15.0);
+    Range rng3 = rng1.intersection(rng2);
+
+    assertEquals(rng1.getMax(),rng3.getMax());
+    assertEquals(rng2.getMin(),rng3.getMin());
+  } 
+}