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62 lines
2.3 KiB
Python
62 lines
2.3 KiB
Python
"""Utilities for testing with Tkinter"""
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import functools
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def run_in_tk_mainloop(delay=1):
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"""Decorator for running a test method with a real Tk mainloop.
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This starts a Tk mainloop before running the test, and stops it
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at the end. This is faster and more robust than the common
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alternative method of calling .update() and/or .update_idletasks().
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Test methods using this must be written as generator functions,
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using "yield" to allow the mainloop to process events and "after"
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callbacks, and then continue the test from that point.
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The delay argument is passed into root.after(...) calls as the number
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of ms to wait before passing execution back to the generator function.
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This also assumes that the test class has a .root attribute,
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which is a tkinter.Tk object.
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For example (from test_sidebar.py):
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@run_test_with_tk_mainloop()
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def test_single_empty_input(self):
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self.do_input('\n')
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yield
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self.assert_sidebar_lines_end_with(['>>>', '>>>'])
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"""
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def decorator(test_method):
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@functools.wraps(test_method)
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def new_test_method(self):
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test_generator = test_method(self)
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root = self.root
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# Exceptions raised by self.assert...() need to be raised
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# outside of the after() callback in order for the test
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# harness to capture them.
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exception = None
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def after_callback():
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nonlocal exception
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try:
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next(test_generator)
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except StopIteration:
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root.quit()
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except Exception as exc:
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exception = exc
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root.quit()
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else:
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# Schedule the Tk mainloop to call this function again,
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# using a robust method of ensuring that it gets a
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# chance to process queued events before doing so.
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# See: https://stackoverflow.com/q/18499082#comment65004099_38817470
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root.after(delay, root.after_idle, after_callback)
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root.after(0, root.after_idle, after_callback)
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root.mainloop()
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if exception:
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raise exception
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return new_test_method
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return decorator
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