test against pypy3

Author: altendky

.travis.yml

@@ -15,6 +15,9 @@ matrix:
       sudo: required
       env:
         - TOXENV=py37,report,codecov
+    - python: 'pypy3'
+      env:
+        - TOXENV=pypy3,report,codecov
     - python: '3.7'
       dist: xenial
       sudo: required

tests/test_make.py

@@ -396,6 +396,11 @@ class B:
     assert_dump_load(schema=schema, loaded=loaded, dumped=dumped)
 
 
+# where 3.6.9 corresponds to PyPy3 release 7.2.0
+@pytest.mark.skipif(
+    condition=sys.implementation.name == "pypy" and sys.version_info < (3, 6, 9),
+    reason="Forward references and string annotations are broken.",
+)
 def test_forward_reference_module_scope():
     """Run the forward reference test at global scope."""