[Snek] [keith-packard/snek] 0f4900: test: Add 'assert' to check in pass-while tests

[Keith Packard]

  Branch: refs/heads/test-while-assert
  Home:   https://github.com/keith-packard/snek
  Commit: 0f4900019c68ff3fbd8a79c61cdecc877118c0a0
      https://github.com/keith-packard/snek/commit/0f4900019c68ff3fbd8a79c61cdecc877118c0a0
  Author: Keith Packard <keithp at keithp.com>
  Date:   2022-01-14 (Fri, 14 Jan 2022)

  Changed paths:
    M test/pass-while-break.py
    M test/pass-while-else.py
    M test/pass-while.py

  Log Message:
  -----------
  test: Add 'assert' to check in pass-while tests

This makes sure an error message is printed if these tests fail.

Signed-off-by: Keith Packard <keithp at keithp.com>