diff --git a/CHANGES/2804.feature b/CHANGES/2804.feature
new file mode 100644
index 00000000000..a92b0051e93
--- /dev/null
+++ b/CHANGES/2804.feature
@@ -0,0 +1,3 @@
+Install a test event loop as default by
+``asyncio.set_event_loop()``. The change affects aiohttp test utils
+but backward compatibility is not broken for 99.99% of use cases.
\ No newline at end of file
diff --git a/aiohttp/pytest_plugin.py b/aiohttp/pytest_plugin.py
index 86c658f3165..5c9d3288c0c 100644
--- a/aiohttp/pytest_plugin.py
+++ b/aiohttp/pytest_plugin.py
@@ -203,8 +203,8 @@ def loop(loop_factory, fast, loop_debug):
     with loop_context(loop_factory, fast=fast) as _loop:
         if loop_debug:
             _loop.set_debug(True)  # pragma: no cover
+        asyncio.set_event_loop(_loop)
         yield _loop
-    asyncio.set_event_loop(None)
 
 
 @pytest.fixture
diff --git a/aiohttp/test_utils.py b/aiohttp/test_utils.py
index 0253daf80e7..b08e2aca786 100644
--- a/aiohttp/test_utils.py
+++ b/aiohttp/test_utils.py
@@ -410,7 +410,7 @@ def setup_test_loop(loop_factory=asyncio.new_event_loop):
     once they are done with the loop.
     """
     loop = loop_factory()
-    asyncio.set_event_loop(None)
+    asyncio.set_event_loop(loop)
     if sys.platform != "win32":
         policy = asyncio.get_event_loop_policy()
         watcher = asyncio.SafeChildWatcher()
diff --git a/docs/testing.rst b/docs/testing.rst
index 845bd6825cd..ed728d4f568 100644
--- a/docs/testing.rst
+++ b/docs/testing.rst
@@ -788,6 +788,20 @@ Utilities
    The caller should also call teardown_test_loop, once they are done
    with the loop.
 
+   .. note::
+
+      As side effect the function changes asyncio *default loop* by
+      :func:`asyncio.set_event_loop` call.
+
+      Previous default loop is not restored.
+
+      It should not be a problem for test suite: every test expects a
+      new test loop instance anyway.
+
+   .. versionchanged:: 3.1
+
+      The function installs a created event loop as *default*.
+
 .. function:: teardown_test_loop(loop)
 
    Teardown and cleanup an event_loop created by setup_test_loop.
diff --git a/tests/test_loop.py b/tests/test_loop.py
index ceb719433a4..246fe4ed3ed 100644
--- a/tests/test_loop.py
+++ b/tests/test_loop.py
@@ -29,4 +29,11 @@ async def on_startup_hook(self, app):
 
     @unittest_run_loop
     async def test_on_startup_hook(self):
-        assert self.startup_loop is not None
+        self.assertIsNotNone(self.startup_loop)
+
+    def test_default_loop(self):
+        self.assertIs(self.loop, asyncio.get_event_loop())
+
+
+def test_default_loop(loop):
+    assert asyncio.get_event_loop() is loop