vim-patch:8.0.1510: cannot assert beep #9938

Problem:    Cannot test if a command causes a beep.
Solution:   Add assert_beeps().
b48e96f61c

src/nvim/eval.lua

@@ -25,6 +25,7 @@ return {
     arglistid={args={0, 2}},
     argv={args={0, 1}},
     asin={args=1, func="float_op_wrapper", data="&asin"},  -- WJMc
+    assert_beeps={args={1, 2}},
     assert_equal={args={2, 3}},
     assert_exception={args={1, 2}},
     assert_fails={args={1, 2}},