make hypothesis optional for testing (#2343)

* make hypothesis optional for testing

* fix coveragin in "_hypothesis_plugin.py"

* uncomment ci checks

pydantic/_hypothesis_plugin.py

@@ -59,7 +59,7 @@ else:
         try:
             email_validator.validate_email(s, check_deliverability=False)
             return True
-        except email_validator.EmailNotValidError:
+        except email_validator.EmailNotValidError:  # pragma: no cover
             return False
 
     # Note that these strategies deliberately stay away from any tricky Unicode
@@ -217,7 +217,7 @@ def resolves(
 def resolve_json(cls):  # type: ignore[no-untyped-def]
     try:
         inner = st.none() if cls.inner_type is None else st.from_type(cls.inner_type)
-    except Exception:
+    except Exception:  # pragma: no cover
         finite = st.floats(allow_infinity=False, allow_nan=False)
         inner = st.recursive(
             base=st.one_of(st.none(), st.booleans(), st.integers(), finite, st.text()),

tests/conftest.py

@@ -10,7 +10,12 @@ import pytest
 from _pytest.assertion.rewrite import AssertionRewritingHook
 
 # See https://hypothesis.readthedocs.io/en/latest/strategies.html#interaction-with-pytest-cov
-pytest_plugins = ['hypothesis.extra.pytestplugin']
+try:
+    import hypothesis  # noqa
+except ImportError:
+    pytest_plugins = []
+else:
+    pytest_plugins = ['hypothesis.extra.pytestplugin']
 
 
 def _extract_source_code_from_function(function):

tests/test_hypothesis_plugin.py

@@ -1,11 +1,21 @@
 import typing
 
 import pytest
-from hypothesis import given, strategies as st
 
 import pydantic
 from pydantic.networks import import_email_validator
 
+try:
+    from hypothesis import given, strategies as st
+except ImportError:
+
+    def given(*args, **kwargs):
+        return lambda f: f
+
+    st = type('st', (), {'data': lambda: None})
+
+    pytestmark = pytest.mark.skipif(True, reason='"hypothesis" not installed')
+
 
 def gen_models():
     class MiscModel(pydantic.BaseModel):