Merge pull request HypothesisWorks#1237 from Zac-HD/typed

Add basic static typing to the Hypothesis API

.gitignore

@@ -4,6 +4,7 @@
 venv*
 .cache
 .pytest_cache
+.mypy_cache
 .hypothesis
 docs/_build
 *.egg-info

.travis.yml

@@ -37,6 +37,7 @@ env:
         - TASK=doctest
         - TASK=check-rst
         - TASK=check-format
+        - TASK=check-type-hints
         - TASK=check-coverage
         - TASK=check-requirements
         - TASK=check-pypy
@@ -65,7 +66,7 @@ env:
         - TASK=deploy
 
 script:
-    - ./build.sh 
+    - ./build.sh
 
 matrix:
     fast_finish: true

hypothesis-python/RELEASE.rst

@@ -0,0 +1,4 @@
+RELEASE_TYPE: patch
+
+This patch contains some internal refactoring to run :pypi:`mypy` in CI.
+There are no user-visible changes.

hypothesis-python/setup.py

@@ -85,6 +85,7 @@ def local_file(name):
     author_email='david@drmaciver.com',
     packages=setuptools.find_packages(SOURCE),
     package_dir={'': SOURCE},
+    # package_data={'': ['py.typed']},  # un-comment to release type hints
     url=(
         'https://github.com/HypothesisWorks/hypothesis/'
         'tree/master/hypothesis-python'

hypothesis-python/src/hypothesis/_settings.py

@@ -38,6 +38,9 @@
 from hypothesis.internal.validation import try_convert
 from hypothesis.utils.dynamicvariables import DynamicVariable
 
+if False:
+    from typing import Dict, List  # noqa
+
 __all__ = [
     'settings',
 ]
@@ -46,7 +49,7 @@
 unlimited = UniqueIdentifier('unlimited')
 
 
-all_settings = {}
+all_settings = {}  # type: Dict[str, Setting]
 
 
 class settingsProperty(object):
@@ -113,7 +116,9 @@ def _assign_default_internal(self, value):
         default_variable.value = value
 
 
-class settings(settingsMeta('settings', (object,), {})):
+class settings(
+    settingsMeta('settings', (object,), {})  # type: ignore
+):
     """A settings object controls a variety of parameters that are used in
     falsification. These may control both the falsification strategy and the
     details of the data that is generated.
@@ -126,7 +131,7 @@ class settings(settingsMeta('settings', (object,), {})):
         '_construction_complete', 'storage'
     ]
     __definitions_are_locked = False
-    _profiles = {}
+    _profiles = {}  # type: dict
 
     def __getattr__(self, name):
         if name in all_settings:
@@ -498,11 +503,11 @@ def _validate_timeout(n):
 )
 
 
-def _validate_database(db, __from_db_file=False):
+def _validate_database(db, _from_db_file=False):
     from hypothesis.database import ExampleDatabase
     if db is None or isinstance(db, ExampleDatabase):
         return db
-    if __from_db_file or db is not_set:
+    if _from_db_file or db is not_set:
         return ExampleDatabase(db)
     raise InvalidArgument(
         'Arguments to the database setting must be None or an instance of '
@@ -533,7 +538,7 @@ def _validate_database(db, __from_db_file=False):
 The file or directory location to save and load previously tried examples;
 `:memory:` for an in-memory cache or None to disable caching entirely.
 """,
-    validator=lambda f: _validate_database(f, __from_db_file=True),
+    validator=lambda f: _validate_database(f, _from_db_file=True),
     deprecation_message="""
 The `database_file` setting is deprecated in favor of the `database`
 setting, and will be removed in a future version.  It only exists at

hypothesis-python/src/hypothesis/core.py

@@ -39,12 +39,12 @@
 from coverage.collector import Collector
 
 import hypothesis.strategies as st
-from hypothesis import __version__
 from hypothesis.errors import Flaky, Timeout, NoSuchExample, \
     Unsatisfiable, DidNotReproduce, InvalidArgument, DeadlineExceeded, \
     MultipleFailures, FailedHealthCheck, HypothesisWarning, \
     UnsatisfiedAssumption, HypothesisDeprecationWarning
 from hypothesis.control import BuildContext
+from hypothesis.version import __version__
 from hypothesis._settings import Phase, Verbosity, HealthCheck, \
     PrintSettings
 from hypothesis._settings import settings as Settings
@@ -74,6 +74,9 @@
 except ImportError:  # pragma: no cover
     from coverage.collector import FileDisposition
 
+if False:
+    from typing import Any, Dict, Callable, Optional  # noqa
+
 
 running_under_pytest = False
 global_force_seed = None
@@ -424,7 +427,7 @@ def __init__(self, filename, source, target):
         self.target = target
 
 
-ARC_CACHE = {}
+ARC_CACHE = {}  # type: Dict[str, Dict[Any, Dict[Any, Arc]]]
 
 
 def arc(filename, source, target):
@@ -890,6 +893,7 @@ def fake_subTest(self, msg=None, **__):
 
 
 def given(*given_arguments, **given_kwargs):
+    # type: (*SearchStrategy, **SearchStrategy) -> Callable
     """A decorator for turning a test function that accepts arguments into a
     randomized test.
 
@@ -1075,7 +1079,14 @@ def wrapped_test(*arguments, **kwargs):
     return run_test_with_generator
 
 
-def find(specifier, condition, settings=None, random=None, database_key=None):
+def find(
+    specifier,  # type: SearchStrategy
+    condition,  # type: Callable[[Any], bool]
+    settings=None,  # type: Settings
+    random=None,   # type: Any
+    database_key=None,  # type: bytes
+):
+    # type: (...) -> Any
     """Returns the minimal example from the given strategy ``specifier`` that
     matches the predicate function ``condition``."""
     settings = settings or Settings(

hypothesis-python/src/hypothesis/database.py

@@ -83,7 +83,9 @@ def __call__(self, *args, **kwargs):
         return super(EDMeta, self).__call__(*args, **kwargs)
 
 
-class ExampleDatabase(EDMeta('ExampleDatabase', (object,), {})):
+class ExampleDatabase(
+    EDMeta('ExampleDatabase', (object,), {})  # type: ignore
+):
     """Interface class for storage systems.
 
     A key -> multiple distinct values mapping.

hypothesis-python/src/hypothesis/internal/charmap.py

@@ -28,6 +28,11 @@
 from hypothesis.configuration import tmpdir, storage_directory
 from hypothesis.internal.compat import hunichr
 
+if False:
+    from typing import Dict, Tuple
+    intervals = Tuple[Tuple[int, int], ...]
+    cache_type = Dict[Tuple[Tuple[str, ...], int, int, intervals], intervals]
+
 
 def charmap_file():
     return os.path.join(
@@ -308,7 +313,7 @@ def _query_for_key(key):
     return result
 
 
-limited_category_index_cache = {}
+limited_category_index_cache = {}  # type: cache_type
 
 
 def query(

hypothesis-python/src/hypothesis/internal/compat.py

@@ -33,8 +33,11 @@
 try:
     from collections import OrderedDict, Counter
 except ImportError:  # pragma: no cover
-    from ordereddict import OrderedDict
-    from counter import Counter
+    from ordereddict import OrderedDict  # type: ignore
+    from counter import Counter  # type: ignore
+
+if False:
+    from typing import Type  # noqa
 
 
 PY2 = sys.version_info[0] == 2
@@ -410,7 +413,7 @@ def __getitem__(self, *args, **kwargs):
         else:
             return r
 
-    __setitem__ = None
+    __setitem__ = None  # type: ignore
 
     def join(self, parts):
         result = bytearray()
@@ -467,15 +470,15 @@ def implements_iterator(it):
 
 
 if PY3:
-    FileNotFoundError = FileNotFoundError
+    FileNotFoundError = FileNotFoundError  # type: Type[IOError]
 else:
     FileNotFoundError = IOError
 
 # We need to know what sort of exception gets thrown when you try to write over
 # an existing file where you're not allowed to. This is rather less consistent
 # between versions than might be hoped.
 if PY3:
-    FileExistsError = FileExistsError
+    FileExistsError = FileExistsError  # type: Type[IOError]
 
 elif WINDOWS:
     FileExistsError = WindowsError
@@ -519,7 +522,7 @@ def b64decode(s):
     from base64 import b64decode
 
 
-_cases = []
+_cases = []  # type: list
 
 
 def bad_django_TestCase(runner):

hypothesis-python/src/hypothesis/internal/conjecture/data.py

@@ -58,7 +58,7 @@ class StructuralTag(object):
     label = attr.ib()
 
 
-STRUCTURAL_TAGS = {}
+STRUCTURAL_TAGS = {}  # type: dict
 
 
 def structural_tag(label):

hypothesis-python/src/hypothesis/internal/conjecture/engine.py

@@ -1018,7 +1018,7 @@ def __init__(self, tag):
         self.tag = tag
 
 
-NEGATED_CACHE = {}
+NEGATED_CACHE = {}  # type: dict
 
 
 def negated(tag):

hypothesis-python/src/hypothesis/internal/coverage.py

@@ -24,6 +24,9 @@
 
 from hypothesis.internal.reflection import proxies
 
+if False:
+    from typing import Set, Dict, Tuple  # noqa
+
 """
 This module implements a custom coverage system that records conditions and
 then validates that every condition has been seen to be both True and False
@@ -37,7 +40,7 @@
 itself and has essentially no overhead.
 """
 
-pretty_file_name_cache = {}
+pretty_file_name_cache = {}  # type: Dict[str, str]
 
 
 def pretty_file_name(f):
@@ -59,7 +62,7 @@ def pretty_file_name(f):
 if IN_COVERAGE_TESTS:
     with open('branch-check', 'w'):
         pass
-    written = set()
+    written = set()  # type: Set[Tuple[str, bool]]
 
     def record_branch(name, value):
         key = (name, value)
@@ -109,7 +112,8 @@ def accept(*args, **kwargs):
     def check_function(f):
         return f
 
-    @contextmanager
+    # Mypy bug: https://github.com/python/mypy/issues/4117
+    @contextmanager  # type: ignore
     def check(name):
         yield
 

hypothesis-python/src/hypothesis/internal/escalation.py

@@ -28,6 +28,9 @@
 from hypothesis.internal.compat import text_type, binary_type, \
     encoded_filepath
 
+if False:
+    from typing import Dict  # noqa
+
 
 def belongs_to(package):
     root = os.path.dirname(package.__file__)
@@ -50,7 +53,7 @@ def accept(filepath):
 
 PREVENT_ESCALATION = os.getenv('HYPOTHESIS_DO_NOT_ESCALATE') == 'true'
 
-FILE_CACHE = {}
+FILE_CACHE = {}  # type: Dict[bytes, bool]
 
 
 is_hypothesis_file = belongs_to(hypothesis)

hypothesis-python/src/hypothesis/internal/reflection.py

@@ -403,7 +403,7 @@ def eval_directory():
     return storage_directory('eval_source')
 
 
-eval_cache = {}
+eval_cache = {}  # type: dict
 
 
 def source_exec_as_module(source):

hypothesis-python/src/hypothesis/searchstrategy/collections.py

@@ -65,8 +65,8 @@ class ListStrategy(SearchStrategy):
     def __init__(self, elements, min_size=0, max_size=float('inf')):
         SearchStrategy.__init__(self)
         self.min_size = min_size or 0
-        self.max_size = max_size or float('inf')
-        assert 0 <= min_size <= max_size
+        self.max_size = max_size if max_size is not None else float('inf')
+        assert 0 <= self.min_size <= self.max_size
         self.average_size = min(
             max(self.min_size * 2, self.min_size + 5),
             0.5 * (self.min_size + self.max_size),

hypothesis-python/src/hypothesis/searchstrategy/lazy.py

@@ -22,7 +22,11 @@
     convert_keyword_arguments, convert_positional_arguments
 from hypothesis.searchstrategy.strategies import SearchStrategy
 
-unwrap_cache = {}
+if False:
+    from typing import Dict  # noqa
+
+
+unwrap_cache = {}  # type: Dict[SearchStrategy, SearchStrategy]
 unwrap_depth = 0