Throw AssumptionViolatedException when single null is passed to Assum…

src/main/java/org/junit/Assume.java

@@ -79,6 +79,7 @@ public static void assumeFalse(String message, boolean b) {
      * If called with one or more null elements in <code>objects</code>, the test will halt and be ignored.
      */
     public static void assumeNotNull(Object... objects) {
+        assumeThat(objects, notNullValue());
         assumeThat(asList(objects), everyItem(notNullValue()));
     }
 

src/test/java/org/junit/tests/experimental/AssumptionTest.java

@@ -110,6 +110,16 @@ public void assumeNotNullThrowsException() {
         }
     }
 
+    @Test
+    public void assumeNotNullSingleNullThrowsException() {
+        try {
+            assumeNotNull(null);
+            fail("should throw AssumptionViolatedException");
+        } catch (AssumptionViolatedException e) {
+            // expected
+        }
+    }
+
     @Test
     public void assumeNotNullPasses() {
         Object[] objects = {1, 2};