custom-set: add to track (#206)

* dibs: I will implement custom-set

* Created an empty project

* Added custom-set exercise to the Java track

config.json

@@ -55,6 +55,7 @@
     "binary-search-tree",
     "binary-search",
     "all-your-base",
+    "custom-set",
     "wordy",
     "palindrome-products"
   ],
@@ -315,6 +316,11 @@
       "topics": []
     },
     {
+      "slug": "custom-set",
+      "difficulty": 1,
+      "topics": []
+    },
+    {
       "slug": "wordy",
       "difficulty": 1,
       "topics": []

exercises/custom-set/build.gradle

@@ -0,0 +1,18 @@
+apply plugin: "java"
+apply plugin: "eclipse"
+apply plugin: "idea"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testCompile "junit:junit:4.12"
+}
+
+test {
+    testLogging {
+        exceptionFormat = 'full'
+        events = ["passed", "failed", "skipped"]
+    }
+}

exercises/custom-set/src/example/java/CustomSet.java

@@ -0,0 +1,74 @@
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+public class CustomSet<T> {
+
+    private Set<T> set;
+
+    public CustomSet() {
+        this(Collections.EMPTY_LIST);
+    }
+
+    public CustomSet(Collection<T> data) {
+        set = new HashSet<>(data.size());
+        this.set.addAll(data);
+    }
+
+    public boolean isEmpty() {
+        return set.isEmpty();
+    }
+
+    public boolean contains(T element) {
+        return set.contains(element);
+    }
+
+    public boolean isSubset(CustomSet<T> anotherSet) {
+        return set.containsAll(anotherSet.set);
+    }
+
+    public boolean isDisjoint(CustomSet<T> anotherSet) {
+        if (set.isEmpty() || anotherSet.set.isEmpty()) {
+            return true;
+        }
+        return set.stream()
+                .filter(elem -> anotherSet.set.contains(elem))
+                .count() == 0;
+    }
+
+    public boolean equals(CustomSet<T> anotherSet) {
+        return set.equals(anotherSet.set);
+    }
+
+    public boolean add(T element) {
+        return set.add(element);
+    }
+
+    public CustomSet<T> getIntersection(CustomSet<T> anotherSet) {
+        return new CustomSet<>(
+                set.stream()
+                        .filter(anotherSet.set::contains)
+                        .collect(Collectors.toList())
+        );
+    }
+
+    public CustomSet<T> getUnion(CustomSet<T> anotherSet) {
+        final Set<T> union = new HashSet<>(set);
+        union.addAll(anotherSet.set);
+        return new CustomSet<>(union);
+    }
+
+    public CustomSet<T> getDifference(CustomSet<T> anotherSet) {
+        final Predicate<T> predicate = anotherSet::contains;
+        return new CustomSet<>(
+                set.stream()
+                        .filter(predicate.negate())
+                        .collect(Collectors.toList())
+        );
+    }
+
+}

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

@@ -0,0 +1,505 @@
+
+import java.util.Arrays;
+import java.util.Collections;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import org.junit.Test;
+import org.junit.Ignore;
+
+public class CustomSetTest {
+
+    @Test
+    public void setsWithNoElementsAreEmpty() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .isEmpty();
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setsWithElementsAreNotEmpty() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1))
+                        .isEmpty();
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void nothingIsContainedInAnEmptySet() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .contains(1);
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void whenTheElementIsInTheSet() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3))
+                        .contains(1);
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void whenTheElementIsNotInTheSet() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3))
+                        .contains(4);
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void emptySetIsASubsetOfAnotherEmptySet() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .isSubset(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void emptySetIsASubsetOfNonEemptySet() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1))
+                        .isSubset(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void nonEmptySetIsNotASubsetOfEmptySet() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .isSubset(
+                                new CustomSet<>(Arrays.asList(1))
+                        );
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setIsASubsetOfSetWithExactSameElements() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3))
+                        .isSubset(
+                                new CustomSet<>(Arrays.asList(1, 2, 3))
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setIsASubsetOfLargerSetWithSameElements() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(4, 1, 2, 3))
+                        .isSubset(
+                                new CustomSet<>(Arrays.asList(1, 2, 3))
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setIsNotASubsetOfSetThatDoesNotContainItsElements() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(4, 1, 3))
+                        .isSubset(
+                                new CustomSet<>(Arrays.asList(1, 2, 3))
+                        );
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void theEmptySetIsDisjointWithItself() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .isDisjoint(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void emptySetIsDisjointWithNonEmptySet() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .isDisjoint(
+                                new CustomSet<>(Arrays.asList(1))
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void nonEmptySetIsDisjointWithEmptySet() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1))
+                        .isDisjoint(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setsAreNotDisjointIfTheyShareAnElement() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2))
+                        .isDisjoint(
+                                new CustomSet<>(Arrays.asList(2, 3))
+                        );
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setsAreDisjointIfTheyShareNoElements() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2))
+                        .isDisjoint(
+                                new CustomSet<>(Arrays.asList(3, 4))
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void emptySetsAreEqual() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .equals(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void emptySetIsNotEqualToNonEmptySet() {
+        final boolean actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .equals(
+                                new CustomSet<>(Arrays.asList(1, 2, 3))
+                        );
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void nonEmptySetIsNotEqualToEmptySet() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3))
+                        .equals(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setsWithTheSameElementsAreEqual() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2))
+                        .equals(
+                                new CustomSet<>(Arrays.asList(2, 1))
+                        );
+
+        assertTrue(actual);
+    }
+
+    @Test
+    @Ignore
+    public void setsWithDifferentElementsAreNotEqual() {
+        final boolean actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3))
+                        .equals(
+                                new CustomSet<>(Arrays.asList(1, 2, 4))
+                        );
+
+        assertFalse(actual);
+    }
+
+    @Test
+    @Ignore
+    public void addToEmptySet() {
+        final int element = 3;
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(element))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Collections.EMPTY_LIST);
+
+        actual.add(element);
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void addToNonEmptySet() {
+        final int element = 3;
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(1, 2, 3, 4))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 2, 4));
+
+        actual.add(element);
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void addingAnExistingElementDoesNotChangeTheSet() {
+        final int element = 3;
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(1, 2, 3))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3));
+
+        actual.add(element);
+
+        assertNotNull(actual);
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void intersectionOfTwoEmptySetsIsAnEmptySet() {
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .getIntersection(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertNotNull(actual);
+        assertTrue(actual.isEmpty());
+    }
+
+    @Test
+    @Ignore
+    public void intersectionOfAnEmptySetAndNonEmptySetIsAnEmptySet() {
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .getIntersection(
+                                new CustomSet<>(Arrays.asList(3, 2, 5))
+                        );
+
+        assertNotNull(actual);
+        assertTrue(actual.isEmpty());
+    }
+
+    @Test
+    @Ignore
+    public void intersectionOfANonEmptySetAndAnEmptySetIsAnEmptySet() {
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3, 4))
+                        .getIntersection(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertNotNull(actual);
+        assertTrue(actual.isEmpty());
+
+    }
+
+    @Test
+    @Ignore
+    public void intersectionOfTwoSetsWithNoSharedElementsIsAnEmptySet() {
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3))
+                        .getIntersection(
+                                new CustomSet<>(Arrays.asList(4, 5, 6))
+                        );
+
+        assertNotNull(actual);
+        assertTrue(actual.isEmpty());
+    }
+
+    @Test
+    @Ignore
+    public void intersectionOfTwoSetsWithSharedElementsIsASetOfTheSharedElements() {
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(2, 3))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3, 4))
+                        .getIntersection(
+                                new CustomSet<>(Arrays.asList(3, 2, 5))
+                        );
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void differenceOfTwoEmptySetsIsAnEmptySet() {
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .getDifference(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertNotNull(actual);
+        assertTrue(actual.isEmpty());
+    }
+
+    @Test
+    @Ignore
+    public void differenceOfAnEmptySetAndNonEmptySetIsAnEmptySet() {
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .getDifference(
+                                new CustomSet<>(Arrays.asList(3, 2, 5))
+                        );
+
+        assertNotNull(actual);
+        assertTrue(actual.isEmpty());
+    }
+
+    @Test
+    @Ignore
+    public void differenceOfANonEmptySetAndAnEmptySetIsTheNonEmptySet() {
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(1, 2, 3, 4))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 2, 3, 4))
+                        .getDifference(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void differenceOfTwoNonEmptySetsIsASetOfElementsThatAreOnlyInTheFirstSet() {
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(1, 3))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(3, 2, 1))
+                        .getDifference(
+                                new CustomSet<>(Arrays.asList(2, 4))
+                        );
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void unionOfTwoEmptySetsIsAnEmptySet() {
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .getUnion(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertNotNull(actual);
+        assertTrue(actual.isEmpty());
+    }
+
+    @Test
+    @Ignore
+    public void unionOfAnEmptySetAndNonEmptySetIsTheNonEmptySet() {
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(2))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Collections.EMPTY_LIST)
+                        .getUnion(
+                                new CustomSet<>(Arrays.asList(2))
+                        );
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void unionOfANonEmptySetAndAnEmptySetIsTheNonEmptySet() {
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(1, 3))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 3))
+                        .getUnion(
+                                new CustomSet<>(Collections.EMPTY_LIST)
+                        );
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+    @Test
+    @Ignore
+    public void unionOfTwoNonEmptySetsContainsAllUniqueElements() {
+        final CustomSet<Integer> expected
+                = new CustomSet<>(
+                        Collections.unmodifiableList(Arrays.asList(3, 2, 1))
+                );
+        final CustomSet<Integer> actual
+                = new CustomSet<>(Arrays.asList(1, 3))
+                        .getUnion(
+                                new CustomSet<>(Arrays.asList(2, 3))
+                        );
+
+        assertNotNull(actual);
+        assertFalse(actual.isEmpty());
+        assertTrue(expected.equals(actual));
+    }
+
+}

exercises/settings.gradle

@@ -10,6 +10,7 @@ include 'binary-search-tree'
 include 'bob'
 include 'bracket-push'
 include 'crypto-square'
+include 'custom-set'
 include 'difference-of-squares'
 include 'etl'
 include 'gigasecond'