Improved the check_type and check_valid_size validation functions

A couple of minor improvements have been made:
- The check_type function now tests for lists of length 1 so the
returned mesaging is better.
- check_valid_size() now passes the name variable into check_type
as this is a required argument.

To cover the additional logic within check_type a new test has
been added in the test_validation file.

CONTRIBUTING.rst

@@ -269,6 +269,7 @@ their individual contributions.
 * `Sushobhit <https://github.com/sushobhit27>`_ (sushobhitsolanki@gmail.com)
 * `Tariq Khokhar <https://www.github.com/tkb>`_ (tariq@khokhar.net)
 * `Tessa Bradbury <https://www.github.com/tessereth>`_
+* `Thomas Grainge <https://www.github.com/tgrainge>`_
 * `Tim Martin <https://www.github.com/timmartin>`_ (tim@asymptotic.co.uk)
 * `Tom McDermott <https://www.github.com/sponster-au>`_ (sponster@gmail.com)
 * `Tyler Gibbons <https://www.github.com/kavec>`_ (tyler.gibbons@flexport.com)

hypothesis-python/RELEASE.rst

@@ -0,0 +1,4 @@
+RELEASE_TYPE: patch
+
+This patch improves the messaging that comes from invalid size arguments
+to collection strategies such as :func:`~hypothesis.strategies.lists`.

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

@@ -31,6 +31,8 @@ def check_type(typ, arg, name=""):
     if name:
         name += "="
     if not isinstance(arg, typ):
+        if isinstance(typ, tuple) and len(typ) == 1:
+            typ = typ[0]
         if isinstance(typ, tuple):
             typ_string = "one of %s" % (", ".join(t.__name__ for t in typ))
         else:
@@ -120,7 +122,7 @@ def check_valid_size(value, name):
             since="2018-10-11",
         )
     else:
-        check_type(integer_types, value)
+        check_type(integer_types, value, name)
     if value < 0:
         raise InvalidArgument(u"Invalid size %s=%r < 0" % (name, value))
 

hypothesis-python/tests/cover/test_validation.py

@@ -23,6 +23,7 @@
 
 from hypothesis import find, given
 from hypothesis.errors import InvalidArgument
+from hypothesis.internal.validation import check_type
 from hypothesis.strategies import (
     binary,
     booleans,
@@ -247,3 +248,10 @@ def test(x):
 
     with pytest.raises(InvalidArgument):
         test()
+
+
+def test_check_type_with_tuple_of_length_two():
+    # This test covers logic for length-two tuples that is essential on PY2,
+    # e.g. string_types (str, unicode) which are all length-one on Python 3.
+    check_type((int, str), 1)
+    check_type((int, str), "1")