Method when

tests/timeline.py:366–370

For every occurrence recorded after this call, invokes callback(occurrence) if occurrence == expectation.

(self, expectation, callback)

        return self._record(occ, block)

    def when(self, expectation, callback):
        """For every occurrence recorded after this call, invokes callback(occurrence)
        if occurrence == expectation.
        """
        self._listeners.append((expectation, callback))

    def _snapshot(self):
        last = self._last