diff --git a/ci.sh b/ci.sh
index 2601b1dcdd..499868ba45 100755
--- a/ci.sh
+++ b/ci.sh
@@ -143,7 +143,7 @@ else
     cd empty
 
     INSTALLDIR=$(python -c "import os, trio; print(os.path.dirname(trio.__file__))")
-    cp ../setup.cfg $INSTALLDIR
+    cp ../pyproject.toml $INSTALLDIR
     # We have to copy .coveragerc into this directory, rather than passing
     # --cov-config=../.coveragerc to pytest, because codecov.sh will run
     # 'coverage xml' to generate the report that it uses, and that will only
diff --git a/pyproject.toml b/pyproject.toml
index 8597a4f545..1378e5df7b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -50,3 +50,10 @@ directory = "misc"
 name = "Miscellaneous internal changes"
 showcontent = true
 
+[tool.pytest.ini_options]
+addopts = ["--strict-markers", "--strict-config"]
+xfail_strict = true
+faulthandler_timeout = 60
+markers = ["redistributors_should_skip: tests that should be skipped by downstream redistributors"]
+junit_family = "xunit2"
+filterwarnings = ["error"]
diff --git a/setup.cfg b/setup.cfg
deleted file mode 100644
index 6f79c6eab9..0000000000
--- a/setup.cfg
+++ /dev/null
@@ -1,9 +0,0 @@
-[tool:pytest]
-xfail_strict = true
-faulthandler_timeout=60
-markers =
-    redistributors_should_skip: tests that should be skipped by downstream redistributors
-junit_family = xunit2
-addopts =
-    -p no:unraisableexception
-    -p no:threadexception
diff --git a/trio/_core/tests/test_asyncgen.py b/trio/_core/tests/test_asyncgen.py
index 1f886e11ab..6ce0af366f 100644
--- a/trio/_core/tests/test_asyncgen.py
+++ b/trio/_core/tests/test_asyncgen.py
@@ -5,7 +5,7 @@
 from functools import partial
 from async_generator import aclosing
 from ... import _core
-from .tutil import gc_collect_harder, buggy_pypy_asyncgens
+from .tutil import gc_collect_harder, buggy_pypy_asyncgens, restore_unraisablehook
 
 
 def test_asyncgen_basics():
@@ -94,8 +94,9 @@ async def agen():
             record.append("crashing")
             raise ValueError("oops")
 
-    await agen().asend(None)
-    gc_collect_harder()
+    with restore_unraisablehook():
+        await agen().asend(None)
+        gc_collect_harder()
     await _core.wait_all_tasks_blocked()
     assert record == ["crashing"]
     exc_type, exc_value, exc_traceback = caplog.records[0].exc_info
@@ -170,6 +171,7 @@ async def async_main():
     assert record == ["innermost"] + list(range(100))
 
 
+@restore_unraisablehook()
 def test_last_minute_gc_edge_case():
     saved = []
     record = []
@@ -267,17 +269,18 @@ async def awaits_after_yield():
             yield 42
         await _core.cancel_shielded_checkpoint()
 
-    await step_outside_async_context(well_behaved())
-    gc_collect_harder()
-    assert capsys.readouterr().err == ""
+    with restore_unraisablehook():
+        await step_outside_async_context(well_behaved())
+        gc_collect_harder()
+        assert capsys.readouterr().err == ""
 
-    await step_outside_async_context(yields_after_yield())
-    gc_collect_harder()
-    assert "ignored GeneratorExit" in capsys.readouterr().err
+        await step_outside_async_context(yields_after_yield())
+        gc_collect_harder()
+        assert "ignored GeneratorExit" in capsys.readouterr().err
 
-    await step_outside_async_context(awaits_after_yield())
-    gc_collect_harder()
-    assert "awaited something during finalization" in capsys.readouterr().err
+        await step_outside_async_context(awaits_after_yield())
+        gc_collect_harder()
+        assert "awaited something during finalization" in capsys.readouterr().err
 
 
 @pytest.mark.skipif(buggy_pypy_asyncgens, reason="pypy 7.2.0 is buggy")
@@ -307,10 +310,11 @@ async def async_main():
         await _core.wait_all_tasks_blocked()
         assert record == ["trio collected ours"]
 
-    old_hooks = sys.get_asyncgen_hooks()
-    sys.set_asyncgen_hooks(my_firstiter, my_finalizer)
-    try:
-        _core.run(async_main)
-    finally:
-        assert sys.get_asyncgen_hooks() == (my_firstiter, my_finalizer)
-        sys.set_asyncgen_hooks(*old_hooks)
+    with restore_unraisablehook():
+        old_hooks = sys.get_asyncgen_hooks()
+        sys.set_asyncgen_hooks(my_firstiter, my_finalizer)
+        try:
+            _core.run(async_main)
+        finally:
+            assert sys.get_asyncgen_hooks() == (my_firstiter, my_finalizer)
+            sys.set_asyncgen_hooks(*old_hooks)
diff --git a/trio/_core/tests/test_guest_mode.py b/trio/_core/tests/test_guest_mode.py
index c9701e7cdd..0184ff3103 100644
--- a/trio/_core/tests/test_guest_mode.py
+++ b/trio/_core/tests/test_guest_mode.py
@@ -13,7 +13,7 @@
 
 import trio
 import trio.testing
-from .tutil import gc_collect_harder, buggy_pypy_asyncgens
+from .tutil import gc_collect_harder, buggy_pypy_asyncgens, restore_unraisablehook
 from ..._util import signal_raise
 
 # The simplest possible "host" loop.
@@ -277,6 +277,7 @@ def after_io_wait(self, timeout):
     assert trivial_guest_run(trio_main) == "ok"
 
 
+@restore_unraisablehook()
 def test_guest_warns_if_abandoned():
     # This warning is emitted from the garbage collector. So we have to make
     # sure that our abandoned run is garbage. The easiest way to do this is to
@@ -506,6 +507,7 @@ async def trio_main(in_host):
     sys.implementation.name == "pypy" and sys.version_info >= (3, 7),
     reason="async generator issue under investigation",
 )
+@restore_unraisablehook()
 def test_guest_mode_asyncgens():
     import sniffio
 
diff --git a/trio/_core/tests/test_run.py b/trio/_core/tests/test_run.py
index d2bcdfd740..8d92e6cec4 100644
--- a/trio/_core/tests/test_run.py
+++ b/trio/_core/tests/test_run.py
@@ -23,6 +23,7 @@
     gc_collect_harder,
     ignore_coroutine_never_awaited_warnings,
     buggy_pypy_asyncgens,
+    restore_unraisablehook,
 )
 
 from ... import _core
@@ -844,6 +845,7 @@ async def stubborn_sleeper():
     assert record == ["sleep", "woke", "cancelled"]
 
 
+@restore_unraisablehook()
 def test_broken_abort():
     async def main():
         # These yields are here to work around an annoying warning -- we're
@@ -870,6 +872,7 @@ async def main():
     gc_collect_harder()
 
 
+@restore_unraisablehook()
 def test_error_in_run_loop():
     # Blow stuff up real good to check we at least get a TrioInternalError
     async def main():
@@ -2154,6 +2157,7 @@ def abort_fn(_):
     assert abort_fn_called
 
 
+@restore_unraisablehook()
 def test_async_function_implemented_in_C():
     # These used to crash because we'd try to mutate the coroutine object's
     # cr_frame, but C functions don't have Python frames.
diff --git a/trio/_core/tests/test_thread_cache.py b/trio/_core/tests/test_thread_cache.py
index 0f6e0a0715..d60288b3c1 100644
--- a/trio/_core/tests/test_thread_cache.py
+++ b/trio/_core/tests/test_thread_cache.py
@@ -3,8 +3,9 @@
 from queue import Queue
 import time
 import sys
+from contextlib import contextmanager
 
-from .tutil import slow, gc_collect_harder
+from .tutil import slow, gc_collect_harder, disable_threading_excepthook
 from .. import _thread_cache
 from .._thread_cache import start_thread_soon, ThreadCache
 
@@ -99,6 +100,17 @@ def test_idle_threads_exit(monkeypatch):
     assert not seen_thread.is_alive()
 
 
+@contextmanager
+def _join_started_threads():
+    before = frozenset(threading.enumerate())
+    try:
+        yield
+    finally:
+        for thread in threading.enumerate():
+            if thread not in before:
+                thread.join()
+
+
 def test_race_between_idle_exit_and_job_assignment(monkeypatch):
     # This is a lock where the first few times you try to acquire it with a
     # timeout, it waits until the lock is available and then pretends to time
@@ -138,13 +150,15 @@ def release(self):
 
     monkeypatch.setattr(_thread_cache, "Lock", JankyLock)
 
-    tc = ThreadCache()
-    done = threading.Event()
-    tc.start_thread_soon(lambda: None, lambda _: done.set())
-    done.wait()
-    # Let's kill the thread we started, so it doesn't hang around until the
-    # test suite finishes. Doesn't really do any harm, but it can be confusing
-    # to see it in debug output. This is hacky, and leaves our ThreadCache
-    # object in an inconsistent state... but it doesn't matter, because we're
-    # not going to use it again anyway.
-    tc.start_thread_soon(lambda: None, lambda _: sys.exit())
+    with disable_threading_excepthook(), _join_started_threads():
+        tc = ThreadCache()
+        done = threading.Event()
+        tc.start_thread_soon(lambda: None, lambda _: done.set())
+        done.wait()
+        # Let's kill the thread we started, so it doesn't hang around until the
+        # test suite finishes. Doesn't really do any harm, but it can be confusing
+        # to see it in debug output. This is hacky, and leaves our ThreadCache
+        # object in an inconsistent state... but it doesn't matter, because we're
+        # not going to use it again anyway.
+
+        tc.start_thread_soon(lambda: None, lambda _: sys.exit())
diff --git a/trio/_core/tests/test_windows.py b/trio/_core/tests/test_windows.py
index e6bab82204..bd81ef0f33 100644
--- a/trio/_core/tests/test_windows.py
+++ b/trio/_core/tests/test_windows.py
@@ -8,7 +8,7 @@
 # Mark all the tests in this file as being windows-only
 pytestmark = pytest.mark.skipif(not on_windows, reason="windows only")
 
-from .tutil import slow, gc_collect_harder
+from .tutil import slow, gc_collect_harder, restore_unraisablehook
 from ... import _core, sleep, move_on_after
 from ...testing import wait_all_tasks_blocked
 
@@ -111,6 +111,7 @@ def pipe_with_overlapped_read():
         kernel32.CloseHandle(ffi.cast("HANDLE", write_handle))
 
 
+@restore_unraisablehook()
 def test_forgot_to_register_with_iocp():
     with pipe_with_overlapped_read() as (write_fp, read_handle):
         with write_fp:
diff --git a/trio/_core/tests/tutil.py b/trio/_core/tests/tutil.py
index 00669e883e..7f51750869 100644
--- a/trio/_core/tests/tutil.py
+++ b/trio/_core/tests/tutil.py
@@ -1,5 +1,6 @@
 # Utilities for testing
 import socket as stdlib_socket
+import threading
 import os
 import sys
 from typing import TYPE_CHECKING
@@ -80,6 +81,40 @@ def ignore_coroutine_never_awaited_warnings():
             gc_collect_harder()
 
 
+def _noop(*args, **kwargs):
+    pass
+
+
+if sys.version_info >= (3, 8):
+
+    @contextmanager
+    def restore_unraisablehook():
+        sys.unraisablehook, prev = sys.__unraisablehook__, sys.unraisablehook
+        try:
+            yield
+        finally:
+            sys.unraisablehook = prev
+
+    @contextmanager
+    def disable_threading_excepthook():
+        threading.excepthook, prev = _noop, threading.excepthook
+        try:
+            yield
+        finally:
+            threading.excepthook = prev
+
+
+else:
+
+    @contextmanager
+    def restore_unraisablehook():  # pragma: no cover
+        yield
+
+    @contextmanager
+    def disable_threading_excepthook():  # pragma: no cover
+        yield
+
+
 # template is like:
 #   [1, {2.1, 2.2}, 3] -> matches [1, 2.1, 2.2, 3] or [1, 2.2, 2.1, 3]
 def check_sequence_matches(seq, template):