diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 969e460054..a1e0cd46c5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['3.6', '3.7', '3.8', '3.9']
+        python: ['3.6', '3.7', '3.8', '3.9', '3.10']
         arch: ['x86', 'x64']
         lsp: ['']
         lsp_extract_file: ['']
@@ -41,7 +41,15 @@ jobs:
       - name: Setup python
         uses: actions/setup-python@v2
         with:
-          python-version: '${{ matrix.python }}'
+          # This allows the matrix to specify just the major.minor version while still
+          # expanding it to get the latest patch version including alpha releases.
+          # This avoids the need to update for each new alpha, beta, release candidate,
+          # and then finally an actual release version.  actions/setup-python doesn't
+          # support this for PyPy presently so we get no help there.
+          # 
+          # CPython -> 3.9.0-alpha - 3.9.X
+          # PyPy    -> pypy-3.7
+          python-version: ${{ fromJSON(format('["{0}", "{1}"]', format('{0}.0-alpha - {0}.X', matrix.python), matrix.python))[startsWith(matrix.python, 'pypy')] }}
           architecture: '${{ matrix.arch }}'
       - name: Run tests
         run: ./ci.sh
@@ -59,7 +67,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['pypy-3.6', 'pypy-3.7', '3.6', '3.7', '3.8', '3.9', '3.8-dev', '3.9-dev']
+        python: ['pypy-3.6', 'pypy-3.7', '3.6', '3.7', '3.8', '3.9', '3.10', '3.8-dev', '3.9-dev', '3.10-dev']
         check_formatting: ['0']
         pypy_nightly_branch: ['']
         extra_name: ['']
@@ -77,7 +85,7 @@ jobs:
         uses: actions/setup-python@v2
         if: "!endsWith(matrix.python, '-dev')"
         with:
-          python-version: '${{ matrix.python }}'
+          python-version: ${{ fromJSON(format('["{0}", "{1}"]', format('{0}.0-alpha - {0}.X', matrix.python), matrix.python))[startsWith(matrix.python, 'pypy')] }}
       - name: Setup python (dev)
         uses: deadsnakes/action@v2.0.2
         if: endsWith(matrix.python, '-dev')
@@ -98,14 +106,14 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['3.6', '3.7', '3.8', '3.9']
+        python: ['3.6', '3.7', '3.8', '3.9', '3.10']
     steps:
       - name: Checkout
         uses: actions/checkout@v2
       - name: Setup python
         uses: actions/setup-python@v2
         with:
-          python-version: '${{ matrix.python }}'
+          python-version: ${{ fromJSON(format('["{0}", "{1}"]', format('{0}.0-alpha - {0}.X', matrix.python), matrix.python))[startsWith(matrix.python, 'pypy')] }}
       - name: Run tests
         run: ./ci.sh
         env:
diff --git a/docs/source/reference-lowlevel.rst b/docs/source/reference-lowlevel.rst
index ebd0f57c03..2fe773cbb7 100644
--- a/docs/source/reference-lowlevel.rst
+++ b/docs/source/reference-lowlevel.rst
@@ -785,7 +785,7 @@ Here's how we'd extend our asyncio example to implement this pattern:
            asyncio_loop.call_soon_threadsafe(fn)
 
        # Revised 'done' callback: set a Future
-       done_fut = asyncio.Future()
+       done_fut = asyncio_loop.create_future()
        def done_callback(trio_main_outcome):
            done_fut.set_result(trio_main_outcome)
 
diff --git a/notes-to-self/aio-guest-test.py b/notes-to-self/aio-guest-test.py
index 5e9b398132..b64a11bd04 100644
--- a/notes-to-self/aio-guest-test.py
+++ b/notes-to-self/aio-guest-test.py
@@ -4,7 +4,7 @@
 async def aio_main():
     loop = asyncio.get_running_loop()
 
-    trio_done_fut = asyncio.Future()
+    trio_done_fut = loop.create_future()
     def trio_done_callback(main_outcome):
         print(f"trio_main finished: {main_outcome!r}")
         trio_done_fut.set_result(main_outcome)
diff --git a/trio/_core/_multierror.py b/trio/_core/_multierror.py
index 13fc3f3d0f..ed926c029f 100644
--- a/trio/_core/_multierror.py
+++ b/trio/_core/_multierror.py
@@ -381,10 +381,13 @@ def traceback_exception_init(
     limit=None,
     lookup_lines=True,
     capture_locals=False,
+    compact=False,
     _seen=None,
 ):
-    if _seen is None:
-        _seen = set()
+    if sys.version_info >= (3, 10):
+        kwargs = {"compact": compact}
+    else:
+        kwargs = {}
 
     # Capture the original exception and its cause and context as TracebackExceptions
     traceback_exception_original_init(
@@ -396,8 +399,14 @@ def traceback_exception_init(
         lookup_lines=lookup_lines,
         capture_locals=capture_locals,
         _seen=_seen,
+        **kwargs,
     )
 
+    seen_was_none = _seen is None
+
+    if _seen is None:
+        _seen = set()
+
     # Capture each of the exceptions in the MultiError along with each of their causes and contexts
     if isinstance(exc_value, MultiError):
         embedded = []
@@ -411,7 +420,7 @@ def traceback_exception_init(
                         capture_locals=capture_locals,
                         # copy the set of _seen exceptions so that duplicates
                         # shared between sub-exceptions are not omitted
-                        _seen=set(_seen),
+                        _seen=None if seen_was_none else set(_seen),
                     )
                 )
         self.embedded = embedded
diff --git a/trio/_core/tests/test_guest_mode.py b/trio/_core/tests/test_guest_mode.py
index 0184ff3103..b06849a836 100644
--- a/trio/_core/tests/test_guest_mode.py
+++ b/trio/_core/tests/test_guest_mode.py
@@ -323,7 +323,7 @@ def aiotrio_run(trio_fn, *, pass_not_threadsafe=True, **start_guest_run_kwargs):
     loop = asyncio.new_event_loop()
 
     async def aio_main():
-        trio_done_fut = asyncio.Future()
+        trio_done_fut = loop.create_future()
 
         def trio_done_callback(main_outcome):
             print(f"trio_fn finished: {main_outcome!r}")
diff --git a/trio/_core/tests/test_run.py b/trio/_core/tests/test_run.py
index 02f5954e60..c56aaaa092 100644
--- a/trio/_core/tests/test_run.py
+++ b/trio/_core/tests/test_run.py
@@ -24,6 +24,7 @@
     ignore_coroutine_never_awaited_warnings,
     buggy_pypy_asyncgens,
     restore_unraisablehook,
+    create_asyncio_future_in_new_loop,
 )
 
 from ... import _core
@@ -1574,9 +1575,7 @@ async def async_gen(arg):  # pragma: no cover
 
 def test_calling_asyncio_function_gives_nice_error():
     async def child_xyzzy():
-        import asyncio
-
-        await asyncio.Future()
+        await create_asyncio_future_in_new_loop()
 
     async def misguided():
         await child_xyzzy()
@@ -1598,7 +1597,7 @@ async def test_asyncio_function_inside_nursery_does_not_explode():
             import asyncio
 
             nursery.start_soon(sleep_forever)
-            await asyncio.Future()
+            await create_asyncio_future_in_new_loop()
     assert "asyncio" in str(excinfo.value)
 
 
diff --git a/trio/_core/tests/tutil.py b/trio/_core/tests/tutil.py
index 7f51750869..3e8053f71f 100644
--- a/trio/_core/tests/tutil.py
+++ b/trio/_core/tests/tutil.py
@@ -1,4 +1,5 @@
 # Utilities for testing
+import asyncio
 import socket as stdlib_socket
 import threading
 import os
@@ -7,7 +8,7 @@
 
 import pytest
 import warnings
-from contextlib import contextmanager
+from contextlib import contextmanager, closing
 
 import gc
 
@@ -97,7 +98,11 @@ def restore_unraisablehook():
 
     @contextmanager
     def disable_threading_excepthook():
-        threading.excepthook, prev = _noop, threading.excepthook
+        if sys.version_info >= (3, 10):
+            threading.excepthook, prev = threading.__excepthook__, threading.excepthook
+        else:
+            threading.excepthook, prev = _noop, threading.excepthook
+
         try:
             yield
         finally:
@@ -135,3 +140,8 @@ def check_sequence_matches(seq, template):
     and os.uname().release[:4] < "12.2",
     reason="hangs on FreeBSD 12.1 and earlier, due to FreeBSD bug #246350",
 )
+
+
+def create_asyncio_future_in_new_loop():
+    with closing(asyncio.new_event_loop()) as loop:
+        return loop.create_future()
diff --git a/trio/tests/test_exports.py b/trio/tests/test_exports.py
index 374ce8c044..ef7edb4ccb 100644
--- a/trio/tests/test_exports.py
+++ b/trio/tests/test_exports.py
@@ -1,3 +1,4 @@
+import re
 import sys
 import importlib
 import types
@@ -69,6 +70,17 @@ def public_modules(module):
 )
 @pytest.mark.parametrize("modname", PUBLIC_MODULE_NAMES)
 @pytest.mark.parametrize("tool", ["pylint", "jedi"])
+@pytest.mark.filterwarnings(
+    "ignore:"
+    + re.escape(
+        "The distutils package is deprecated and slated for removal in Python 3.12. "
+        "Use setuptools or check PEP 632 for potential alternatives"
+    )
+    + ":DeprecationWarning",
+    "ignore:"
+    + re.escape("The distutils.sysconfig module is deprecated, use sysconfig instead")
+    + ":DeprecationWarning",
+)
 def test_static_tool_sees_all_symbols(tool, modname):
     module = importlib.import_module(modname)
 
diff --git a/trio/tests/test_ssl.py b/trio/tests/test_ssl.py
index 1a2e66212d..75f99df137 100644
--- a/trio/tests/test_ssl.py
+++ b/trio/tests/test_ssl.py
@@ -1,3 +1,4 @@
+import re
 import sys
 
 import pytest
@@ -1198,6 +1199,9 @@ async def test_selected_npn_protocol_before_handshake(client_ctx):
         server.selected_npn_protocol()
 
 
+@pytest.mark.filterwarnings(
+    r"ignore: ssl module. NPN is deprecated, use ALPN instead:UserWarning"
+)
 async def test_selected_npn_protocol_when_not_set(client_ctx):
     # NPN protocol still returns None when it's not set,
     # instead of raising an exception
diff --git a/trio/tests/test_util.py b/trio/tests/test_util.py
index 2ea0a1e287..2d57e0ebfc 100644
--- a/trio/tests/test_util.py
+++ b/trio/tests/test_util.py
@@ -3,7 +3,10 @@
 
 import trio
 from .. import _core
-from .._core.tests.tutil import ignore_coroutine_never_awaited_warnings
+from .._core.tests.tutil import (
+    ignore_coroutine_never_awaited_warnings,
+    create_asyncio_future_in_new_loop,
+)
 from .._util import (
     signal_raise,
     ConflictDetector,
@@ -114,11 +117,11 @@ def generator_based_coro():  # pragma: no cover
         assert "asyncio" in str(excinfo.value)
 
         with pytest.raises(TypeError) as excinfo:
-            coroutine_or_error(asyncio.Future())
+            coroutine_or_error(create_asyncio_future_in_new_loop())
         assert "asyncio" in str(excinfo.value)
 
         with pytest.raises(TypeError) as excinfo:
-            coroutine_or_error(lambda: asyncio.Future())
+            coroutine_or_error(create_asyncio_future_in_new_loop)
         assert "asyncio" in str(excinfo.value)
 
         with pytest.raises(TypeError) as excinfo: