Waiting for Assertions
WaitFor class can be used to wait for a condition to hold. You can use it within your tests to wait for some asynchronous process to complete and so make an assertion in a test.
In the example below, a test verifies that the action of clicking a button will toggle some switch to a different position. However, this test may or may not pass if the
clickButton() kicks off an asynchronous process to update the toggle position. It may return immediately having not yet changed the position.
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Rewriting the test using a
WaitFor would look like this
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Here, the test will retry the
Condition for five seconds before finally giving up and failing the test. If the condition is true immediately, the wait will continue immediately and the test will continue. By extracting a method to create the
Condition, you can further refactor the test to be more expressive and start to create a library of reusable conditions.
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A wait which times out will through a
TimeoutException although, since 1.2, you can also supply the
waitOrTimeout call with behaviour to execute on timeout (as a
Callable). For example;
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will not throw a
TimeoutException but instead notify some observer of the failure. Refactored a little, it would look like this
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