Improve testing

I believe it would be nice to have
tests on CI not only for Python 3.7,
but for all supported Python versions.

These changes:

 - fix compatibility with Python 3.5 and 3.4

 - add tests for various Python versions on CI

 - allow running tests for any branches

Author: Jamim

.travis.yml

@@ -3,14 +3,19 @@ dist: xenial
 language: python
 
 python:
+  - '3.4'
+  - '3.5'
+  - '3.6'
   - '3.7'
+  - 'pypy3.5'
+  - '3.8-dev'
+
+matrix:
+  allow_failures:
+    - python: '3.8-dev'
 
 install:
   - pip install tox-travis
 
 script:
   - tox
-
-branches:
-  only:
-    - master

ext/opentelemetry-ext-wsgi/tests/test_wsgi_middleware.py

@@ -94,7 +94,7 @@ def tearDown(self):
 
     def start_response(self, status, response_headers, exc_info=None):
         # The span should have started already
-        self.span_context_manager.__enter__.assert_called()
+        self.span_context_manager.__enter__.assert_called_with()
 
         self.status = status
         self.response_headers = response_headers
@@ -108,7 +108,9 @@ def validate_response(self, response, error=None):
                 self.span_context_manager.__exit__.assert_not_called()
                 self.assertEqual(value, b"*")
             except StopIteration:
-                self.span_context_manager.__exit__.assert_called()
+                self.span_context_manager.__exit__.assert_called_with(
+                    None, None, None
+                )
                 break
 
         self.assertEqual(self.status, "200 OK")

opentelemetry-api/src/opentelemetry/context/__init__.py

@@ -145,7 +145,9 @@ async def main():
 __all__ = ['Context']
 
 
-Context: typing.Optional[BaseRuntimeContext]
+Context = (  # pylint: disable=invalid-name
+    None
+)  # type: typing.Optional[BaseRuntimeContext]
 
 try:
     from .async_context import AsyncRuntimeContext

opentelemetry-api/src/opentelemetry/context/async_context.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 from contextvars import ContextVar
-import typing
+import typing  # pylint: disable=unused-import
 
 from . import base_context
 
@@ -23,9 +23,10 @@ class Slot(base_context.BaseRuntimeContext.Slot):
         def __init__(self, name: str, default: 'object'):
             # pylint: disable=super-init-not-called
             self.name = name
-            self.contextvar: 'ContextVar[object]' = ContextVar(name)
-            self.default: typing.Callable[..., object]
-            self.default = base_context.wrap_callable(default)
+            self.contextvar = ContextVar(name)  # type: ContextVar[object]
+            self.default = base_context.wrap_callable(
+                default
+            )  # type: typing.Callable[..., object]
 
         def clear(self) -> None:
             self.contextvar.set(self.default())

opentelemetry-api/src/opentelemetry/context/base_context.py

@@ -37,7 +37,7 @@ def set(self, value: 'object') -> None:
             raise NotImplementedError
 
     _lock = threading.Lock()
-    _slots: typing.Dict[str, 'BaseRuntimeContext.Slot'] = {}
+    _slots = {}  # type: typing.Dict[str, 'BaseRuntimeContext.Slot']
 
     @classmethod
     def clear(cls) -> None:
@@ -112,7 +112,7 @@ def with_current_context(
 
         def call_with_current_context(
                 *args: 'object',
-                **kwargs: 'object',
+                **kwargs: 'object'
         ) -> 'object':
             try:
                 backup_context = self.snapshot()

opentelemetry-api/src/opentelemetry/context/thread_local_context.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import threading
-import typing
+import typing  # pylint: disable=unused-import
 
 from . import base_context
 
@@ -25,15 +25,16 @@ class Slot(base_context.BaseRuntimeContext.Slot):
         def __init__(self, name: str, default: 'object'):
             # pylint: disable=super-init-not-called
             self.name = name
-            self.default: typing.Callable[..., object]
-            self.default = base_context.wrap_callable(default)
+            self.default = base_context.wrap_callable(
+                default
+            )  # type: typing.Callable[..., object]
 
         def clear(self) -> None:
             setattr(self._thread_local, self.name, self.default())
 
         def get(self) -> 'object':
             try:
-                got: object = getattr(self._thread_local, self.name)
+                got = getattr(self._thread_local, self.name)  # type: object
                 return got
             except AttributeError:
                 value = self.default()

opentelemetry-api/src/opentelemetry/loader.py

@@ -83,7 +83,7 @@ def my_factory_for_t(api_type: typing.Type[T]) -> typing.Optional[T]:
 # code.
 # ImplementationFactory = Callable[[Type[_T]], Optional[_T]]
 
-_DEFAULT_FACTORY: Optional[_UntrustedImplFactory[object]] = None
+_DEFAULT_FACTORY = None  # type: Optional[_UntrustedImplFactory[object]]
 
 
 def _try_load_impl_from_modname(

opentelemetry-api/src/opentelemetry/trace/__init__.py

@@ -378,9 +378,15 @@ def use_span(self, span: 'Span') -> typing.Iterator[None]:
         yield
 
 
-_TRACER: typing.Optional[Tracer] = None
-_TRACER_FACTORY: typing.Optional[
-    typing.Callable[[typing.Type[Tracer]], typing.Optional[Tracer]]] = None
+# Once https://github.com/python/mypy/issues/7092 is resolved,
+# the following type definition should be replaced with
+# from opentelemetry.loader import ImplementationFactory
+ImplementationFactory = typing.Callable[
+    [typing.Type[Tracer]], typing.Optional[Tracer]
+]
+
+_TRACER = None  # type: typing.Optional[Tracer]
+_TRACER_FACTORY = None  # type: typing.Optional[ImplementationFactory]
 
 
 def tracer() -> Tracer:
@@ -399,9 +405,8 @@ def tracer() -> Tracer:
 
 
 def set_preferred_tracer_implementation(
-        factory: typing.Callable[
-            [typing.Type[Tracer]], typing.Optional[Tracer]]
-        ) -> None:
+        factory: ImplementationFactory
+) -> None:
     """Set the factory to be used to create the tracer.
 
     See :mod:`opentelemetry.loader` for details.

tox.ini

@@ -1,8 +1,9 @@
 [tox]
 skipsdist = True
+skip_missing_interpreters = True
 envlist =
-    py{34,35,36,37}-test-{api,sdk}
-    py{34,35,36,37}-test-ext-wsgi
+    py3{4,5,6,7,8}-test-{api,sdk,ext-wsgi}
+    pypy35-test-{api,sdk,ext-wsgi}
     lint
     py37-mypy
     docs
@@ -24,6 +25,7 @@ changedir =
   test-ext-wsgi: ext/opentelemetry-ext-wsgi/tests
 
 commands_pre =
+  pip install -U pip setuptools wheel
   test: pip install -e {toxinidir}/opentelemetry-api
   test-sdk: pip install -e {toxinidir}/opentelemetry-sdk
   ext: pip install -e {toxinidir}/opentelemetry-api
@@ -36,6 +38,7 @@ commands =
   test: python -m unittest discover
 
 [testenv:lint]
+basepython: python3.7
 deps =
   pylint~=2.3
   flake8~=3.7