Add tests for pushing move only values

unittests/list_push_back.chai

@@ -6,3 +6,9 @@ x.push_back("A")
 
 assert_equal(3, x.front());
 assert_equal("A", x.back());
+
+
+// push_back newly constructed return value that's non-copyable
+x.push_back(async(fun(){}))
+
+

unittests/list_push_front.chai

@@ -6,3 +6,8 @@ x.push_front("A")
 
 assert_equal("A", x.front());
 assert_equal(3, x.back());
+
+// push_back newly constructed return value that's non-copyable
+x.push_front(async(fun(){}))
+
+

unittests/vector_push_back.chai

@@ -11,3 +11,10 @@ auto uint16v = u16vector();
 uint16v.push_back(1u);
 assert_equal(1, uint16v.front());
 
+
+// push_back newly constructed return value that's non-copyable
+
+var v = []
+v.push_back(async(fun(){}))
+
+