Method test_trace

Lib/test/test_tkinter/test_variables.py:182–229

(self)

        self.assertEqual(trace, [('write', vname, '', 'u')])

    def test_trace(self):
        v = Variable(self.root)
        vname = str(v)
        trace = []
        def read_tracer(*args):
            trace.append(('read',) + args)
        def write_tracer(*args):
            trace.append(('write',) + args)
        tr1 = v.trace_add('read', read_tracer)
        tr2 = v.trace_add(['write', 'unset'], write_tracer)
        self.assertEqual(sorted(v.trace_info()), [
                         (('read',), tr1),
                         (('write', 'unset'), tr2)])
        self.assertEqual(trace, [])

        v.set('spam')
        self.assertEqual(trace, [('write', vname, '', 'write')])

        trace = []
        v.get()
        self.assertEqual(trace, [('read', vname, '', 'read')])

        trace = []
        info = sorted(v.trace_info())
        v.trace_remove('write', tr1)  # Wrong mode
        self.assertEqual(sorted(v.trace_info()), info)
        with self.assertRaises(TclError):
            v.trace_remove('read', 'spam')  # Wrong command name
        self.assertEqual(sorted(v.trace_info()), info)
        v.get()
        self.assertEqual(trace, [('read', vname, '', 'read')])

        trace = []
        v.trace_remove('read', tr1)
        self.assertEqual(v.trace_info(), [(('write', 'unset'), tr2)])
        v.get()
        self.assertEqual(trace, [])

        trace = []
        del write_tracer
        gc.collect()
        v.set('eggs')
        self.assertEqual(trace, [('write', vname, '', 'write')])

        trace = []
        del v
        gc.collect()
        self.assertEqual(trace, [('write', vname, '', 'unset')])


class TestStringVar(TestBase):