Fixes #8

Create QueueX

Author: alexengrig

src/main/java/alexengrig/lambdax/collection/QueueX.java

@@ -0,0 +1,35 @@
+package alexengrig.lambdax.collection;
+
+import java.util.Queue;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+
+/**
+ * This utility class contains useful lambdas for {@link Queue}
+ *
+ * @author Grig Alex
+ * @see Queue
+ * @see Consumer
+ * @see Predicate
+ * @since 0.1.0
+ */
+public final class QueueX {
+    private QueueX() {
+    }
+
+    public static <E> Predicate<Queue<? super E>> add(E item) {
+        return q -> q.add(item);
+    }
+
+    public static <E> Consumer<Queue<? super E>> onlyAdd(E item) {
+        return q -> q.add(item);
+    }
+
+    public static <E> Predicate<Queue<? super E>> offer(E item) {
+        return q -> q.offer(item);
+    }
+
+    public static <E> Consumer<Queue<? super E>> onlyOffer(E item) {
+        return q -> q.offer(item);
+    }
+}

src/test/java/alexengrig/lambdax/collection/QueueXTest.java

@@ -0,0 +1,46 @@
+package alexengrig.lambdax.collection;
+
+import org.junit.Test;
+
+import java.util.ArrayDeque;
+import java.util.Queue;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+
+import static org.junit.Assert.assertTrue;
+
+public class QueueXTest {
+    @Test
+    public void checkAdd() {
+        int value = 1;
+        Queue<Number> numbers = new ArrayDeque<>();
+        Predicate<Queue<? super Number>> addValue = QueueX.add(value);
+        assertTrue(addValue.test(numbers));
+    }
+
+    @Test
+    public void checkOnlyAdd() {
+        int value = 2;
+        Queue<Number> numbers = new ArrayDeque<>();
+        Consumer<Queue<? super Number>> onlyAddValue = QueueX.onlyAdd(value);
+        onlyAddValue.accept(numbers);
+        assertTrue(numbers.contains(value));
+    }
+
+    @Test
+    public void checkOffer() {
+        int value = 3;
+        Queue<Number> numbers = new ArrayDeque<>();
+        Predicate<Queue<? super Number>> offerValue = QueueX.offer(value);
+        assertTrue(offerValue.test(numbers));
+    }
+
+    @Test
+    public void checkOnlyOffer() {
+        int value = 4;
+        Queue<Number> numbers = new ArrayDeque<>();
+        Consumer<Queue<? super Number>> onlyOfferValue = QueueX.onlyOffer(value);
+        onlyOfferValue.accept(numbers);
+        assertTrue(numbers.contains(value));
+    }
+}