Properties

doublex supports stub and spy properties in a pretty easy way in relation to other frameworks like python-mock.

That requires two constraints:

• It does not support “free” doubles. ie: you must give a collaborator in the constructor.
• collaborator must be a new-style class. See the next example.

Stubbing properties

from doublex import Spy, assert_that, is_

with Spy(Collaborator) as spy:
    spy.prop = 2  # stubbing 'prop' value

assert_that(spy.prop, is_(2))  # double property getter invoked

Spying properties

Continuing previous example:

from doublex import Spy, assert_that, never
from doublex import property_got, property_set

class Collaborator(object):
    @property
    def prop(self):
        return 1

    @prop.setter
    def prop(self, value):
        pass

spy = Spy(Collaborator)
value = spy.prop

assert_that(spy, property_got('prop'))  # property 'prop' was read.

spy.prop = 4
spy.prop = 5
spy.prop = 5

assert_that(spy, property_set('prop'))  # was set to any value
assert_that(spy, property_set('prop').to(4))
assert_that(spy, property_set('prop').to(5).times(2))
assert_that(spy, never(property_set('prop').to(6)))

Mocking properties

Getting property:

from doublex import Mock, assert_that, verify

with Mock(Collaborator) as mock:
    mock.prop

mock.prop

assert_that(mock, verify())

Setting property:

from doublex import Mock, assert_that, verify

with Mock(Collaborator) as mock:
    mock.prop = 5

mock.prop = 5

assert_that(mock, verify())

Using matchers:

from hamcrest import all_of, greater_than, less_than
from doublex import Mock, assert_that, verify

with Mock(Collaborator) as mock:
    mock.prop = all_of(greater_than(8), less_than(12))

mock.prop = 10

assert_that(mock, verify())