BAEL-1071 Runnable vs Callable in Java (#2513)

core-java-concurrency/src/test/java/com/baeldung/concurrent/callable/FactorialTaskManualTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.concurrent.callable;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import static junit.framework.Assert.assertEquals;
+
+public class FactorialTaskManualTest {
+
+    private ExecutorService executorService;
+
+    @Before
+    public void setup(){
+        executorService = Executors.newSingleThreadExecutor();
+    }
+
+    @Test
+    public void whenTaskSubmitted_ThenFutureResultObtained() throws ExecutionException, InterruptedException {
+        FactorialTask task = new FactorialTask(5);
+        Future<Integer> future= executorService.submit(task);
+        assertEquals(120,future.get().intValue());
+    }
+
+    @Test(expected = ExecutionException.class)
+    public void whenException_ThenCallableThrowsIt() throws ExecutionException, InterruptedException {
+        FactorialTask task = new FactorialTask(-5);
+        Future<Integer> future= executorService.submit(task);
+        Integer result=future.get().intValue();
+    }
+
+    @Test
+    public void whenException_ThenCallableDoesntThrowsItIfGetIsNotCalled(){
+        FactorialTask task = new FactorialTask(-5);
+        Future<Integer> future= executorService.submit(task);
+        assertEquals(false,future.isDone());
+    }
+
+    @After
+    public void cleanup(){
+        executorService.shutdown();
+    }
+}