diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1f5705961..ecdbae1f5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,7 +21,7 @@ jobs:
     strategy:
       matrix:
         runs-on: ["ubuntu-latest", "windows-latest"] # can add macos-latest
-        python-version: ["3.10", "3.11"] # 3.12 should be added when p4p is updated
+        python-version: ["3.10","3.11","3.12"]
         include:
           # Include one that runs in the dev environment
           - runs-on: "ubuntu-latest"
diff --git a/pyproject.toml b/pyproject.toml
index ef4834750..0b71859b4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,6 +9,7 @@ classifiers = [
     "License :: OSI Approved :: BSD License",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
 ]
 description = "Asynchronous Bluesky hardware abstraction code, compatible with control systems like EPICS and Tango"
 dependencies = [
@@ -98,8 +99,12 @@ addopts = """
     --doctest-glob="*.rst" --doctest-glob="*.md"
     --ignore=docs/examples --ignore=src/ophyd_async/epics/signal.py
     """
-# https://iscinumpy.gitlab.io/post/bound-version-constraints/#watch-for-warnings
-filterwarnings = "error"
+# "error" for https://iscinumpy.gitlab.io/post/bound-version-constraints/#watch-for-warnings
+# "tango" for https://github.com/bluesky/ophyd-async/issues/681
+filterwarnings = """
+error
+ignore::DeprecationWarning:tango.asyncio_executor:  
+"""
 # Doctest python code in docs, python code in src docstrings, test functions in tests
 testpaths = "docs src tests"
 log_format = "%(asctime)s,%(msecs)03d %(levelname)s (%(threadName)s) %(message)s"
diff --git a/tests/conftest.py b/tests/conftest.py
index ce6221841..871162d99 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -89,7 +89,9 @@ def _error_and_kill_pending_tasks(
     unfinished_tasks = {
         task
         for task in asyncio.all_tasks(loop)
-        if task.get_coro().__name__ not in _ALLOWED_PYTEST_TASKS and not task.done()
+        if (coro := task.get_coro()) is not None
+        and coro.__name__ not in _ALLOWED_PYTEST_TASKS
+        and not task.done()
     }
     for task in unfinished_tasks:
         task.cancel()
@@ -113,15 +115,22 @@ def fail_test_on_unclosed_tasks(request: FixtureRequest):
     by the end of the test.
     """
 
-    fail_count = request.session.testsfailed
-    loop = asyncio.get_event_loop()
-    loop.set_debug(True)
+    try:
+        fail_count = request.session.testsfailed
+        loop = asyncio.get_running_loop()
+
+        loop.set_debug(True)
 
-    request.addfinalizer(
-        lambda: _error_and_kill_pending_tasks(
-            loop, request.node.name, request.session.testsfailed == fail_count
+        request.addfinalizer(
+            lambda: _error_and_kill_pending_tasks(
+                loop, request.node.name, request.session.testsfailed == fail_count
+            )
         )
-    )
+    # Once https://github.com/bluesky/ophyd-async/issues/683
+    # is finished we can remove this try, except.
+    except RuntimeError as error:
+        if str(error) != "no running event loop":
+            raise error
 
 
 @pytest.fixture(scope="function")
diff --git a/tests/core/test_mock_signal_backend.py b/tests/core/test_mock_signal_backend.py
index 046f0097f..f44e8ef5f 100644
--- a/tests/core/test_mock_signal_backend.py
+++ b/tests/core/test_mock_signal_backend.py
@@ -185,6 +185,7 @@ async def test_blocks_during_put(mock_signals):
     with mock_puts_blocked(signal1, signal2):
         status1 = signal1.set("second_value", wait=True, timeout=None)
         status2 = signal2.set("second_value", wait=True, timeout=None)
+        await asyncio.sleep(0.1)
         assert await signal1.get_value() == "second_value"
         assert await signal2.get_value() == "second_value"
         assert not status1.done
diff --git a/tests/core/test_readable.py b/tests/core/test_readable.py
index 8b39fb404..d0c781d19 100644
--- a/tests/core/test_readable.py
+++ b/tests/core/test_readable.py
@@ -32,13 +32,13 @@ def test_standard_readable_hints():
 
     assert sr.hints == {}
 
-    hint1 = MagicMock()
+    hint1 = MagicMock(spec=HasHints)
     hint1.hints = {"fields": ["abc"], "dimensions": [(["f1", "f2"], "s1")]}
 
-    hint2 = MagicMock()
+    hint2 = MagicMock(spec=HasHints)
     hint2.hints = {"fields": ["def", "ghi"]}
 
-    hint3 = MagicMock()
+    hint3 = MagicMock(spec=HasHints)
     hint3.hints = {"fields": ["jkl"], "gridding": "rectilinear_nonsequential"}
 
     sr.add_readables([hint1, hint2, hint3])
@@ -53,10 +53,10 @@ def test_standard_readable_hints():
 def test_standard_readable_hints_raises_when_overriding_string_literal():
     sr = StandardReadable()
 
-    hint1 = MagicMock()
+    hint1 = MagicMock(spec=HasHints)
     hint1.hints = {"gridding": "rectilinear_nonsequential"}
 
-    hint2 = MagicMock()
+    hint2 = MagicMock(spec=HasHints)
     hint2.hints = {"gridding": "a different string"}
 
     sr._has_hints = (
@@ -71,10 +71,10 @@ def test_standard_readable_hints_raises_when_overriding_string_literal():
 def test_standard_readable_hints_raises_when_overriding_sequence():
     sr = StandardReadable()
 
-    hint1 = MagicMock()
+    hint1 = MagicMock(spec=HasHints)
     hint1.hints = {"fields": ["field1", "field2"]}
 
-    hint2 = MagicMock()
+    hint2 = MagicMock(spec=HasHints)
     hint2.hints = {"fields": ["field2"]}
 
     sr._has_hints = (
@@ -90,7 +90,7 @@ def test_standard_readable_hints_raises_when_overriding_sequence():
 def test_standard_readable_hints_invalid_types(invalid_type):
     sr = StandardReadable()
 
-    hint1 = MagicMock()
+    hint1 = MagicMock(spec=HasHints)
     hint1.hints = {"test": invalid_type}
 
     sr._has_hints = (hint1,)
diff --git a/tests/epics/adcore/test_drivers.py b/tests/epics/adcore/test_drivers.py
index f2b2dcadc..e04ee9ff1 100644
--- a/tests/epics/adcore/test_drivers.py
+++ b/tests/epics/adcore/test_drivers.py
@@ -90,10 +90,12 @@ async def wait_then_fail():
         await asyncio.sleep(0)
         set_mock_value(driver.detector_state, adcore.DetectorState.DISCONNECTED)
 
+    await wait_then_fail()
+
     acquiring = await adcore.start_acquiring_driver_and_ensure_status(
         driver, timeout=0.1
     )
-    await wait_then_fail()
-
-    with pytest.raises(ValueError):
+    with pytest.raises(
+        ValueError, match="Final detector state DetectorState.DISCONNECTED"
+    ):
         await acquiring
diff --git a/tests/sim/demo/test_sim_motor.py b/tests/sim/demo/test_sim_motor.py
index 9a8ac75a6..d879c717b 100644
--- a/tests/sim/demo/test_sim_motor.py
+++ b/tests/sim/demo/test_sim_motor.py
@@ -1,6 +1,7 @@
 import asyncio
 import time
 
+import pytest
 from bluesky.plans import spiral_square
 from bluesky.run_engine import RunEngine
 
@@ -49,6 +50,7 @@ async def test_stop():
     new_pos = await m1.user_readback.get_value()
     assert new_pos < 10
     assert new_pos >= 0.1
-    # move should not be successful as we stopped it
-    assert move_status.done
+
     assert not move_status.success
+    with pytest.raises(RuntimeError, match="Motor was stopped"):
+        await move_status