Add test cases for BagAddOccurrencesProcedure. Closes #989

Signed-off-by: jonathansamuel-bnym <jonathan.samuel@bnymellon.com>

unit-tests/src/test/java/org/eclipse/collections/impl/block/procedure/BagAddOccurrencesProcedureTest.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2020 The Bank of New York Mellon and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * and Eclipse Distribution License v. 1.0 which accompany this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
+ * and the Eclipse Distribution License is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ */
+
+package org.eclipse.collections.impl.block.procedure;
+
+import org.eclipse.collections.api.bag.MutableBag;
+import org.eclipse.collections.api.factory.Bags;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class BagAddOccurrencesProcedureTest
+{
+    @Test
+    public void basicCase()
+    {
+        MutableBag<String> targetCollection = Bags.mutable.empty();
+        BagAddOccurrencesProcedure<String> procedure = new BagAddOccurrencesProcedure<>(targetCollection);
+
+        procedure.value("fred", 1);
+        procedure.value("fred", 1);
+        procedure.value("mary", 3);
+
+        Assert.assertEquals(2, procedure.getResult().occurrencesOf("fred"));
+        Assert.assertEquals(3, procedure.getResult().occurrencesOf("mary"));
+        Assert.assertEquals(0, procedure.getResult().occurrencesOf("other"));
+    }
+
+    @Test
+    public void basicCaseUsingFactoryMethod()
+    {
+        MutableBag<String> targetCollection = Bags.mutable.empty();
+        BagAddOccurrencesProcedure<String> procedure = BagAddOccurrencesProcedure.on(targetCollection);
+
+        procedure.value("fred", 1);
+        procedure.value("fred", 1);
+        procedure.value("mary", 3);
+
+        Assert.assertEquals(2, procedure.getResult().occurrencesOf("fred"));
+        Assert.assertEquals(3, procedure.getResult().occurrencesOf("mary"));
+        Assert.assertEquals(0, procedure.getResult().occurrencesOf("other"));
+    }
+}