Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/hypothesis/strategies/_internal/deferred.py: 38%

1# This file is part of Hypothesis, which may be found at 

2# https://github.com/HypothesisWorks/hypothesis/ 

3# 

4# Copyright the Hypothesis Authors. 

5# Individual contributors are listed in AUTHORS.rst and the git log. 

6# 

7# This Source Code Form is subject to the terms of the Mozilla Public License, 

8# v. 2.0. If a copy of the MPL was not distributed with this file, You can 

9# obtain one at https://mozilla.org/MPL/2.0/. 

10 

11import inspect 

12 

13from hypothesis.configuration import check_sideeffect_during_initialization 

14from hypothesis.errors import InvalidArgument 

15from hypothesis.internal.reflection import get_pretty_function_description 

16from hypothesis.strategies._internal.strategies import SearchStrategy, check_strategy 

17 

18 

19class DeferredStrategy(SearchStrategy): 

20 """A strategy which may be used before it is fully defined.""" 

21 

22 def __init__(self, definition): 

23 super().__init__() 

24 self.__wrapped_strategy = None 

25 self.__in_repr = False 

26 self.__definition = definition 

27 

28 @property 

29 def wrapped_strategy(self): 

30 if self.__wrapped_strategy is None: 

31 check_sideeffect_during_initialization("deferred evaluation of {!r}", self) 

32 

33 if not inspect.isfunction(self.__definition): 

34 raise InvalidArgument( 

35 f"Expected definition to be a function but got {self.__definition!r} " 

36 f"of type {type(self.__definition).__name__} instead." 

37 ) 

38 result = self.__definition() 

39 if result is self: 

40 raise InvalidArgument("Cannot define a deferred strategy to be itself") 

41 check_strategy(result, "definition()") 

42 self.__wrapped_strategy = result 

43 self.__definition = None 

44 return self.__wrapped_strategy 

45 

46 @property 

47 def branches(self): 

48 return self.wrapped_strategy.branches 

49 

50 @property 

51 def supports_find(self): 

52 return self.wrapped_strategy.supports_find 

53 

54 def calc_label(self): 

55 """Deferred strategies don't have a calculated label, because we would 

56 end up having to calculate the fixed point of some hash function in 

57 order to calculate it when they recursively refer to themself! 

58 

59 The label for the wrapped strategy will still appear because it 

60 will be passed to draw. 

61 """ 

62 # This is actually the same as the parent class implementation, but we 

63 # include it explicitly here in order to document that this is a 

64 # deliberate decision. 

65 return self.class_label 

66 

67 def calc_is_empty(self, recur): 

68 return recur(self.wrapped_strategy) 

69 

70 def calc_has_reusable_values(self, recur): 

71 return recur(self.wrapped_strategy) 

72 

73 def __repr__(self): 

74 if self.__wrapped_strategy is not None: 

75 if self.__in_repr: 

76 return f"(deferred@{id(self)!r})" 

77 try: 

78 self.__in_repr = True 

79 return repr(self.__wrapped_strategy) 

80 finally: 

81 self.__in_repr = False 

82 else: 

83 description = get_pretty_function_description(self.__definition) 

84 return f"deferred({description})" 

85 

86 def do_draw(self, data): 

87 return data.draw(self.wrapped_strategy)