CustomSetTest : add hint to @Ignore annotations

#446

exercises/custom-set/src/test/java/CustomSetTest.java

     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setsWithElementsAreNotEmpty() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void nothingIsContainedInAnEmptySet() {
         final boolean actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void whenTheElementIsInTheSet() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void whenTheElementIsNotInTheSet() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void emptySetIsASubsetOfAnotherEmptySet() {
         final boolean actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void emptySetIsASubsetOfNonEemptySet() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void nonEmptySetIsNotASubsetOfEmptySet() {
         final boolean actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setIsASubsetOfSetWithExactSameElements() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setIsASubsetOfLargerSetWithSameElements() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(4, 1, 2, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setIsNotASubsetOfSetThatDoesNotContainItsElements() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(4, 1, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void theEmptySetIsDisjointWithItself() {
         final boolean actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void emptySetIsDisjointWithNonEmptySet() {
         final boolean actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void nonEmptySetIsDisjointWithEmptySet() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setsAreNotDisjointIfTheyShareAnElement() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setsAreDisjointIfTheyShareNoElements() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void emptySetsAreEqual() {
         final boolean actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void emptySetIsNotEqualToNonEmptySet() {
         final boolean actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void nonEmptySetIsNotEqualToEmptySet() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setsWithTheSameElementsAreEqual() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void setsWithDifferentElementsAreNotEqual() {
         final boolean actual
                 = new CustomSet<>(Arrays.asList(1, 2, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void addToEmptySet() {
         final int element = 3;
         final CustomSet<Integer> expected
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void addToNonEmptySet() {
         final int element = 3;
         final CustomSet<Integer> expected
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void addingAnExistingElementDoesNotChangeTheSet() {
         final int element = 3;
         final CustomSet<Integer> expected
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void intersectionOfTwoEmptySetsIsAnEmptySet() {
         final CustomSet<Integer> actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void intersectionOfAnEmptySetAndNonEmptySetIsAnEmptySet() {
         final CustomSet<Integer> actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void intersectionOfANonEmptySetAndAnEmptySetIsAnEmptySet() {
         final CustomSet<Integer> actual
                 = new CustomSet<>(Arrays.asList(1, 2, 3, 4))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void intersectionOfTwoSetsWithNoSharedElementsIsAnEmptySet() {
         final CustomSet<Integer> actual
                 = new CustomSet<>(Arrays.asList(1, 2, 3))
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void intersectionOfTwoSetsWithSharedElementsIsASetOfTheSharedElements() {
         final CustomSet<Integer> expected
                 = new CustomSet<>(
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void differenceOfTwoEmptySetsIsAnEmptySet() {
         final CustomSet<Integer> actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void differenceOfAnEmptySetAndNonEmptySetIsAnEmptySet() {
         final CustomSet<Integer> actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void differenceOfANonEmptySetAndAnEmptySetIsTheNonEmptySet() {
         final CustomSet<Integer> expected
                 = new CustomSet<>(
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void differenceOfTwoNonEmptySetsIsASetOfElementsThatAreOnlyInTheFirstSet() {
         final CustomSet<Integer> expected
                 = new CustomSet<>(
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void unionOfTwoEmptySetsIsAnEmptySet() {
         final CustomSet<Integer> actual
                 = new CustomSet<>(Collections.EMPTY_LIST)
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void unionOfAnEmptySetAndNonEmptySetIsTheNonEmptySet() {
         final CustomSet<Integer> expected
                 = new CustomSet<>(
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void unionOfANonEmptySetAndAnEmptySetIsTheNonEmptySet() {
         final CustomSet<Integer> expected
                 = new CustomSet<>(
     }
 
     @Test
-    @Ignore
+    @Ignore("Remove to run test")
     public void unionOfTwoNonEmptySetsContainsAllUniqueElements() {
         final CustomSet<Integer> expected
                 = new CustomSet<>(