perfect-numbers: update to canonical tests v1.0.0 (#336)

exercises/perfect-numbers/src/example/java/NaturalNumber.java

     private final int naturalNumber;
 
     NaturalNumber(int naturalNumber) {
-        if (naturalNumber <= 0) throw new IllegalStateException("Natural numbers are all positive.");
+        if (naturalNumber <= 0) throw new IllegalArgumentException("You must supply a natural number (positive integer)");
         this.naturalNumber = naturalNumber;
     }
 

exercises/perfect-numbers/src/test/java/NaturalNumberTest.java

 import org.junit.Ignore;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import static org.junit.Assert.assertEquals;
 
+/*
+ * version: 1.0.0
+ * https://github.com/exercism/x-common/blob/19d0c7714ce664a1ad762af624c17f8e269fa8b2/exercises/perfect-numbers/canonical-data.json
+ */
 public final class NaturalNumberTest {
 
+    /*
+     * See https://github.com/junit-team/junit4/wiki/Rules for information on JUnit Rules in general and
+     * ExpectedExceptions in particular.
+     */
+    @Rule
+    public ExpectedException expectedException = ExpectedException.none();
+
     @Test
     public void testSmallPerfectNumberIsClassifiedCorrectly() {
         assertEquals(Classification.PERFECT, new NaturalNumber(6).getClassification());
     @Ignore
     @Test
     public void testMediumAbundantNumberIsClassifiedCorrectly() {
-        assertEquals(Classification.ABUNDANT, new NaturalNumber(24).getClassification());
+        assertEquals(Classification.ABUNDANT, new NaturalNumber(30).getClassification());
     }
 
     @Ignore
 
     @Ignore
     @Test
-    public void testSmallDeficientNumberIsClassifiedCorrectly() {
-        assertEquals(Classification.DEFICIENT, new NaturalNumber(8).getClassification());
+    public void testSmallestPrimeDeficientNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.DEFICIENT, new NaturalNumber(2).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testSmallestNonPrimeDeficientNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.DEFICIENT, new NaturalNumber(4).getClassification());
     }
 
     @Ignore
     @Test
-    public void testMediumNumberIsClassifiedCorrectly() {
-        assertEquals(Classification.DEFICIENT, new NaturalNumber(31).getClassification());
+    public void testMediumDeficientNumberIsClassifiedCorrectly() {
+        assertEquals(Classification.DEFICIENT, new NaturalNumber(32).getClassification());
     }
 
     @Ignore
         assertEquals(Classification.DEFICIENT, new NaturalNumber(33550337).getClassification());
     }
 
+    @Ignore
+    @Test
+    /*
+     * The number 1 has no proper divisors (https://en.wikipedia.org/wiki/Divisor#Further_notions_and_facts), and the
+     * additive identity is 0, so the aliquot sum of 1 should be 0. Hence 1 should be classified as deficient.
+     */
+    public void testThatOneIsCorrectlyClassifiedAsDeficient() {
+        assertEquals(Classification.DEFICIENT, new NaturalNumber(1).getClassification());
+    }
+
+    @Ignore
+    @Test
+    public void testThatNonNegativeIntegerIsRejected() {
+        expectedException.expect(IllegalArgumentException.class);
+        expectedException.expectMessage("You must supply a natural number (positive integer)");
+
+        new NaturalNumber(0);
+    }
+
+    @Ignore
+    @Test
+    public void testThatNegativeIntegerIsRejected() {
+        expectedException.expect(IllegalArgumentException.class);
+        expectedException.expectMessage("You must supply a natural number (positive integer)");
+
+        new NaturalNumber(-1);
+    }
+
 }