diff --git a/test/test_as_future.py b/test/test_as_future.py
index 43cf0b6..2df3d83 100644
--- a/test/test_as_future.py
+++ b/test/test_as_future.py
@@ -30,7 +30,7 @@ import txaio
 from util import run_once
 
 
-def test_as_future_immediate():
+def test_as_future_immediate(framework):
     '''
     Returning an immediate value from as_future
     '''
@@ -59,7 +59,7 @@ def test_as_future_immediate():
     assert calls[0] == ((1, 2, 3), dict(key='word'))
 
 
-def test_as_future_immediate_none():
+def test_as_future_immediate_none(framework):
     '''
     Returning None immediately from as_future
     '''
@@ -88,7 +88,7 @@ def test_as_future_immediate_none():
     assert calls[0] == ((1, 2, 3), dict(key='word'))
 
 
-def test_as_future_coroutine():
+def test_as_future_coroutine(framework):
     '''
     call a coroutine (asyncio)
     '''
@@ -127,7 +127,7 @@ def test_as_future_coroutine():
     assert calls[0] == ((1, 2, 3), dict(key='word'))
 
 
-def test_as_future_exception():
+def test_as_future_exception(framework):
     '''
     Raises an exception from as_future
     '''
@@ -157,7 +157,7 @@ def test_as_future_exception():
     assert calls[0] == ((1, 2, 3), dict(key='word'))
 
 
-def test_as_future_recursive():
+def test_as_future_recursive(framework):
     '''
     Returns another Future from as_future
     '''
diff --git a/test/test_call_later.py b/test/test_call_later.py
index 4edf9bb..f9b34f7 100644
--- a/test/test_call_later.py
+++ b/test/test_call_later.py
@@ -31,20 +31,23 @@ import txaio
 from txaio.testutil import replace_loop
 
 
-def test_default_reactor():
+def test_default_reactor(framework_tx):
     """
     run the code that defaults txaio.config.loop
     """
     pytest.importorskip('twisted')
 
     assert txaio.config.loop is None
-    txaio.call_later(1, lambda: None)
+    try:
+        txaio.call_later(1, lambda: None)
 
-    from twisted.internet import reactor
-    assert txaio.config.loop is reactor
+        from twisted.internet import reactor
+        assert txaio.config.loop is reactor
+    finally:
+        txaio.config.loop = None
 
 
-def test_explicit_reactor_future():
+def test_explicit_reactor_future(framework):
     """
     If we set an event-loop, Futures + Tasks should use it.
     """
@@ -61,7 +64,7 @@ def test_explicit_reactor_future():
         assert c[0] == 'call_soon'
 
 
-def test_explicit_reactor_coroutine():
+def test_explicit_reactor_coroutine(framework):
     """
     If we set an event-loop, Futures + Tasks should use it.
     """
@@ -83,7 +86,7 @@ def test_explicit_reactor_coroutine():
         assert c[0] == 'call_soon'
 
 
-def test_call_later():
+def test_call_later(framework_tx):
     '''
     Wait for two Futures.
     '''
diff --git a/test/test_callback.py b/test/test_callback.py
index 44c3299..16ba45c 100644
--- a/test/test_callback.py
+++ b/test/test_callback.py
@@ -29,7 +29,7 @@ import txaio
 from util import run_once
 
 
-def test_default_resolve():
+def test_default_resolve(framework):
     f = txaio.create_future()
     results = []
 
@@ -44,7 +44,7 @@ def test_default_resolve():
     assert results[0] is None
 
 
-def test_callback():
+def test_callback(framework):
     f = txaio.create_future()
     results = []
 
@@ -59,7 +59,7 @@ def test_callback():
     assert results[0] == "it worked"
 
 
-def test_chained_callback():
+def test_chained_callback(framework):
     """
     Chain two callbacks where the first one alters the value.
     """
@@ -84,7 +84,7 @@ def test_chained_callback():
     assert calls[1] == "the deal pray I do not alter it futher"
 
 
-def test_immediate_result():
+def test_immediate_result(framework):
     f = txaio.create_future_success("it worked")
     results = []
 
diff --git a/test/test_create.py b/test/test_create.py
index c1e43f3..2cc078b 100644
--- a/test/test_create.py
+++ b/test/test_create.py
@@ -1,7 +1,7 @@
 import txaio
 
 
-def test_illegal_args():
+def test_illegal_args(framework):
     try:
         txaio.create_future(result=1, error=RuntimeError("foo"))
         assert False
@@ -9,7 +9,7 @@ def test_illegal_args():
         pass
 
 
-def test_create_result():
+def test_create_result(framework):
     f = txaio.create_future(result='foo')
     if txaio.using_twisted:
         assert f.called
@@ -17,7 +17,7 @@ def test_create_result():
         assert f.done()
 
 
-def test_create_error():
+def test_create_error(framework):
     f = txaio.create_future(error=RuntimeError("test"))
     if txaio.using_twisted:
         assert f.called
diff --git a/test/test_errback.py b/test/test_errback.py
index aa7cfe0..b4e4ed2 100644
--- a/test/test_errback.py
+++ b/test/test_errback.py
@@ -29,7 +29,7 @@ import txaio
 from util import run_once
 
 
-def test_errback():
+def test_errback(framework):
     f = txaio.create_future()
     exception = RuntimeError("it failed")
     errors = []
@@ -58,7 +58,7 @@ def test_errback():
     assert 'it failed' in str(errors[0])
 
 
-def test_errback_without_except():
+def test_errback_without_except(framework):
     '''
     Create a failure without an except block
     '''
@@ -84,7 +84,7 @@ def test_errback_without_except():
     assert 'it failed' in str(errors[0])
 
 
-def test_errback_plain_exception():
+def test_errback_plain_exception(framework):
     '''
     reject a future with just an Exception
     '''
@@ -109,7 +109,7 @@ def test_errback_plain_exception():
     assert 'it failed' in str(errors[0])
 
 
-def test_errback_illegal_args():
+def test_errback_illegal_args(framework):
     '''
     non-Exception/Failures should be rejected
     '''
@@ -121,7 +121,7 @@ def test_errback_illegal_args():
         pass
 
 
-def test_errback_reject_no_args():
+def test_errback_reject_no_args(framework):
     """
     txaio.reject() with no args
     """
@@ -151,7 +151,7 @@ def test_errback_reject_no_args():
     assert 'it failed' in str(errors[0])
 
 
-def test_immediate_failure():
+def test_immediate_failure(framework):
     exception = RuntimeError("it failed")
     try:
         raise exception
diff --git a/test/test_gather.py b/test/test_gather.py
index 58aaecf..9d3f176 100644
--- a/test/test_gather.py
+++ b/test/test_gather.py
@@ -29,7 +29,7 @@ import txaio
 from util import await
 
 
-def test_gather_two():
+def test_gather_two(framework_tx):
     '''
     Wait for two Futures.
     '''
@@ -72,7 +72,7 @@ def test_gather_two():
     assert calls[1] == (tuple(), dict())
 
 
-def test_gather_no_consume():
+def test_gather_no_consume(framework_tx):
     '''
     consume_exceptions=False
     '''
diff --git a/test/test_imports.py b/test/test_imports.py
index 30e748e..911ab89 100644
--- a/test/test_imports.py
+++ b/test/test_imports.py
@@ -1,7 +1,7 @@
 import pytest
 
 
-def test_use_twisted():
+def test_use_twisted(framework_tx):
     pytest.importorskip('twisted')
 
     import txaio
@@ -10,7 +10,7 @@ def test_use_twisted():
     assert not txaio.using_asyncio
 
 
-def test_use_twisted_no_twisted():
+def test_use_twisted_no_twisted(framework_uninitialized):
     # make sure we DO NOT have Twisted installed
     try:
         import twisted  # noqa
@@ -26,20 +26,12 @@ def test_use_twisted_no_twisted():
         pass
 
     assert not txaio.using_twisted
-    assert txaio.using_asyncio
 
 
-def test_use_asyncio():
+def test_use_asyncio(framework_aio):
     pytest.importorskip('asyncio')
 
-    # note: in the py34-twisted environments we have both, so make
-    # sure we "put it back"...
     import txaio
-    tx = txaio.using_twisted
-    try:
-        txaio.use_asyncio()
-        assert txaio.using_asyncio
-        assert not txaio.using_twisted
-    finally:
-        if tx:
-            txaio.use_twisted()
+    txaio.use_asyncio()
+    assert txaio.using_asyncio
+    assert not txaio.using_twisted
diff --git a/test/test_is_future.py b/test/test_is_future.py
index c08eac3..c67c453 100644
--- a/test/test_is_future.py
+++ b/test/test_is_future.py
@@ -24,11 +24,10 @@
 #
 ###############################################################################
 
-import pytest
 import txaio
 
 
-def test_is_future_generic():
+def test_is_future_generic(framework):
     '''
     Returning an immediate value from as_future
     '''
@@ -37,14 +36,10 @@ def test_is_future_generic():
     assert txaio.is_future(f)
 
 
-def test_is_future_coroutine():
+def test_is_future_coroutine(framework_aio):
     '''
     Returning an immediate value from as_future
     '''
-    pytest.importorskip('asyncio')
-    if not txaio.using_asyncio:
-        pytest.skip()
-
     from asyncio import coroutine
 
     @coroutine
diff --git a/test/test_logging.py b/test/test_logging.py
index e574910..ef708d4 100644
--- a/test/test_logging.py
+++ b/test/test_logging.py
@@ -46,8 +46,8 @@ class TestHandler(BytesIO):
         return self.getvalue().split(os.linesep.encode('ascii'))[:-1]
 
 
-@pytest.fixture(scope='session')
-def log_started():
+@pytest.fixture
+def log_started(framework):
     """
     Sets up the logging, which we can only do once per run.
     """
@@ -69,7 +69,7 @@ def handler(log_started):
     return log_started
 
 
-def test_critical(handler):
+def test_critical(handler, framework):
     logger = txaio.make_logger()
 
     # do something a little fancy, with attribute access etc.
@@ -83,7 +83,7 @@ def test_critical(handler):
     assert handler.messages[0].endswith(b"hilarious wombat")
 
 
-def test_info(handler):
+def test_info(handler, framework):
     logger = txaio.make_logger()
 
     # do something a little fancy, with attribute access etc.
@@ -97,13 +97,13 @@ def test_info(handler):
     assert handler.messages[0].endswith(b"hilarious elephant")
 
 
-def test_bad_failures(handler):
+def test_bad_failures(handler, framework):
     # just ensuring this doesn't explode
     txaio.failure_format_traceback("not a failure")
     txaio.failure_message("not a failure")
 
 
-def test_debug_with_object(handler):
+def test_debug_with_object(handler, framework):
     logger = txaio.make_logger()
 
     class Shape(object):
@@ -120,7 +120,7 @@ def test_debug_with_object(handler):
     assert handler.messages[0].endswith(b"bar 4 bamboozle")
 
 
-def test_log_noop_trace(handler):
+def test_log_noop_trace(handler, framework):
     # trace should be a no-op, because we set the level to 'debug' in
     # the fixture
     logger = txaio.make_logger()
@@ -130,14 +130,14 @@ def test_log_noop_trace(handler):
     assert len(handler.messages) == 0
 
 
-def test_double_start(handler):
+def test_double_start(handler, framework):
     try:
         txaio.start_logging()
     except RuntimeError:
         assert False, "shouldn't get exception"
 
 
-def test_invalid_level():
+def test_invalid_level(framework):
     try:
         txaio.start_logging(level='foo')
         assert False, "should get exception"
@@ -145,7 +145,7 @@ def test_invalid_level():
         assert 'Invalid log level' in str(e)
 
 
-def test_class_descriptor(handler):
+def test_class_descriptor(handler, framework):
     class Something(object):
         log = txaio.make_logger()
 
@@ -159,7 +159,7 @@ def test_class_descriptor(handler):
     assert handler.messages[0].endswith(b"doing a thing")
 
 
-def test_class_attribute(handler):
+def test_class_attribute(handler, framework):
     class Something(object):
         def __init__(self):
             self.log = txaio.make_logger()
@@ -174,7 +174,7 @@ def test_class_attribute(handler):
     assert handler.messages[0].endswith(b"doing a thing")
 
 
-def test_log_converter(handler):
+def test_log_converter(handler, framework):
     pytest.importorskip("twisted.logger")
     # this checks that we can convert a plain Twisted Logger calling
     # failure() into a traceback on our observers.
@@ -195,7 +195,7 @@ def test_log_converter(handler):
     assert "Traceback" in output
 
 
-def test_txlog_write_binary(handler):
+def test_txlog_write_binary(handler, framework):
     """
     Writing to a binary stream is supported.
     """
@@ -216,7 +216,7 @@ def test_txlog_write_binary(handler):
     assert b"hi: hello" in output
 
 
-def test_txlog_write_text(handler):
+def test_txlog_write_text(handler, framework_tx):
     """
     Writing to a text stream is supported.
     """
@@ -237,7 +237,7 @@ def test_txlog_write_text(handler):
     assert u"hi: hello" in output
 
 
-def test_aiolog_write_binary(handler):
+def test_aiolog_write_binary(handler, framework_aio):
     """
     Writing to a binary stream is supported.
     """
@@ -257,7 +257,7 @@ def test_aiolog_write_binary(handler):
     assert b"hi: hello" in output
 
 
-def test_aiolog_write_text(handler):
+def test_aiolog_write_text(handler, framework_aio):
     """
     Writing to a text stream is supported.
     """