Merge pull request ReactiveX#3436 from artem-zinnatullin/operator-finally-null-action-check

1.x: Add action != null check in OperatorFinally

Author: akarnokd

src/main/java/rx/internal/operators/OperatorFinally.java

@@ -33,6 +33,9 @@ public final class OperatorFinally<T> implements Operator<T, T> {
     final Action0 action;
 
     public OperatorFinally(Action0 action) {
+        if (action == null) {
+            throw new NullPointerException("Action can not be null");
+        }
         this.action = action;
     }
 

src/test/java/rx/internal/operators/OperatorFinallyTest.java

@@ -15,6 +15,8 @@
  */
 package rx.internal.operators;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -53,4 +55,14 @@ public void testFinallyCalledOnComplete() {
     public void testFinallyCalledOnError() {
         checkActionCalled(Observable.<String> error(new RuntimeException("expected")));
     }
+
+    @Test
+    public void nullActionShouldBeCheckedInConstructor() {
+        try {
+            new OperatorFinally<Object>(null);
+            fail();
+        } catch (NullPointerException expected) {
+            assertEquals("Action can not be null", expected.getMessage());
+        }
+    }
 }