refactor maybe tests

tests/test_maybe.py

@@ -13,38 +13,61 @@
 from hypothesis import given
 from hypothesis.strategies import integers
 
+import pytest
 
-def wrong_mapper(_):
-    assert True is False
 
+class MaybeSpy:
 
-def test_maybe_eq_operator_shuld_compare_values():
+    def mapper(self, value):
+        return value + 1
 
-    assert Maybe.just(42) == Maybe.just(42)
+    def binder(self, value):
+        return Maybe.just(value + 1)
+
+
+@pytest.fixture()
+def maybe_spy(mocker):
+    spy = MaybeSpy()
+    mocker.spy(spy, 'mapper')
+    mocker.spy(spy, 'binder')
+
+    return spy
+
+
+@given(integers())
+def test_maybe_eq_operator_should_compare_values(integer):
+
+    assert Maybe.just(integer) == Maybe.just(integer)
     assert Maybe.just(None) == Maybe.just(None)
 
-    assert Maybe.just(42) != Maybe.nothing()
+    assert Maybe.just(integer) != Maybe.nothing()
 
 
-def test_maybe_map_operator_should_be_applied_only_on_just_value():
+@given(integers())
+def test_maybe_map_operator_should_be_applied_only_on_just_value(integer):
     assert Maybe.just(42).map(increase) == Maybe.just(43)
     assert Maybe.nothing().map(increase) == Maybe.nothing()
 
 
-def test_maybe_map_should_not_call_mapper_when_monad_has_nothing():
-    Maybe.nothing().map(wrong_mapper)
+def test_maybe_map_should_not_call_mapper_when_monad_has_nothing(maybe_spy):
+    Maybe.nothing().map(maybe_spy.binder)
+
+    assert maybe_spy.binder.call_count == 0
 
 
-def test_maybe_bind_should_retrun_result_of_mapper_called_with_maybe_value():
+def test_maybe_bind_should_retrun_result_of_mapper_called_with_maybe_value(maybe_spy):
     assert Maybe.just(42).bind(increase) == 43
 
 
-def test_maybe_bind_should_not_call_mapper_when_monad_has_nothing():
-    Maybe.nothing().bind(wrong_mapper)
+def test_maybe_bind_should_not_call_mapper_when_monad_has_nothing(maybe_spy):
+    Maybe.nothing().bind(maybe_spy.binder)
 
+    assert maybe_spy.binder.call_count == 0
 
-def test_maybe_get_or_else_method_should_return_maybe_value_when_monad_is_not_empty():
-    assert Maybe.just(42).get_or_else(0) == 42
+
+@given(integers())
+def test_maybe_get_or_else_method_should_return_maybe_value_when_monad_is_not_empty(integer):
+    assert Maybe.just(integer).get_or_else(0) is integer
 
 
 @given(integers())