Minor follow-on to PR #1334 (Fix enum value's __int__ returning non-int when...

Minor follow-on to PR #1334 (Fix enum value's __int__ returning non-int when underlying type is bool or of char type) (#3232)

* Minor tweaks.

* Restoring tests/pybind11_tests.h version from master, removing just the comment and empty line that was added in PR #3087; those were made obsolete by the pragma cleanup that concluded with PR #3186.

* More-to-the-point test for Python 3.

tests/test_enum.py

 # -*- coding: utf-8 -*-
 import pytest
 
+import env
 from pybind11_tests import enums as m
 
 
@@ -238,20 +239,26 @@ def test_duplicate_enum_name():
 
 def test_char_underlying_enum():  # Issue #1331/PR #1334:
     assert type(m.ScopedCharEnum.Positive.__int__()) is int
-    assert int(m.ScopedChar16Enum.Zero) == 0  # int() call should successfully return
+    assert int(m.ScopedChar16Enum.Zero) == 0
     assert hash(m.ScopedChar32Enum.Positive) == 1
-    assert m.ScopedCharEnum.Positive.__getstate__() == 1  # return type is long in py2.x
+    if env.PY2:
+        assert m.ScopedCharEnum.Positive.__getstate__() == 1  # long
+    else:
+        assert type(m.ScopedCharEnum.Positive.__getstate__()) is int
     assert m.ScopedWCharEnum(1) == m.ScopedWCharEnum.Positive
     with pytest.raises(TypeError):
-        # Enum should construct with a int, even with char underlying type
-        m.ScopedWCharEnum("0")
+        # Even if the underlying type is char, only an int can be used to construct the enum:
+        m.ScopedCharEnum("0")
 
 
 def test_bool_underlying_enum():
     assert type(m.ScopedBoolEnum.TRUE.__int__()) is int
     assert int(m.ScopedBoolEnum.FALSE) == 0
     assert hash(m.ScopedBoolEnum.TRUE) == 1
-    assert m.ScopedBoolEnum.TRUE.__getstate__() == 1
+    if env.PY2:
+        assert m.ScopedBoolEnum.TRUE.__getstate__() == 1  # long
+    else:
+        assert type(m.ScopedBoolEnum.TRUE.__getstate__()) is int
     assert m.ScopedBoolEnum(1) == m.ScopedBoolEnum.TRUE
     # Enum could construct with a bool
     # (bool is a strict subclass of int, and False will be converted to 0)