Update black, and run auto formatting over the codebase (#9381)

 - Update black version to the latest
 - Run black auto formatting over the codebase
    - Run autoformatting according to [`docs/code_style.md
`](https://github.com/matrix-org/synapse/blob/80d6dc9783aa80886a133756028984dbf8920168/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version

4 files changed, 23 insertions, 15 deletions

diff --git a/tests/util/caches/test_deferred_cache.py b/tests/util/caches/test_deferred_cache.py

index ecd9efc4df..c24c33ee91 100644
--- a/tests/util/caches/test_deferred_cache.py
+++ b/tests/util/caches/test_deferred_cache.py
@@ -232,7 +232,10 @@ class DeferredCacheTestCase(TestCase):
 
     def test_eviction_iterable(self):
         cache = DeferredCache(
-            "test", max_entries=3, apply_cache_factor_from_config=False, iterable=True,
+            "test",
+            max_entries=3,
+            apply_cache_factor_from_config=False,
+            iterable=True,
         )
 
         cache.prefill(1, ["one", "two"])
diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py

index cf1e3203a4..afb11b9caf 100644
--- a/tests/util/caches/test_descriptors.py
+++ b/tests/util/caches/test_descriptors.py
@@ -143,8 +143,7 @@ class DescriptorTestCase(unittest.TestCase):
         obj.mock.assert_not_called()
 
     def test_cache_with_sync_exception(self):
-        """If the wrapped function throws synchronously, things should continue to work
-        """
+        """If the wrapped function throws synchronously, things should continue to work"""
 
         class Cls:
             @cached()
@@ -165,8 +164,7 @@ class DescriptorTestCase(unittest.TestCase):
         self.failureResultOf(d, SynapseError)
 
     def test_cache_with_async_exception(self):
-        """The wrapped function returns a failure
-        """
+        """The wrapped function returns a failure"""
 
         class Cls:
             result = None
@@ -282,7 +280,8 @@ class DescriptorTestCase(unittest.TestCase):
                 try:
                     d = obj.fn(1)
                     self.assertEqual(
-                        current_context(), SENTINEL_CONTEXT,
+                        current_context(),
+                        SENTINEL_CONTEXT,
                     )
                     yield d
                     self.fail("No exception thrown")
@@ -374,8 +373,7 @@ class DescriptorTestCase(unittest.TestCase):
         obj.mock.assert_not_called()
 
     def test_cache_iterable_with_sync_exception(self):
-        """If the wrapped function throws synchronously, things should continue to work
-        """
+        """If the wrapped function throws synchronously, things should continue to work"""
 
         class Cls:
             @descriptors.cached(iterable=True)
diff --git a/tests/util/test_itertools.py b/tests/util/test_itertools.py

index 1ef0af8e8f..e931a7ec18 100644
--- a/tests/util/test_itertools.py
+++ b/tests/util/test_itertools.py
@@ -24,28 +24,32 @@ class ChunkSeqTests(TestCase):
         parts = chunk_seq("123", 8)
 
         self.assertEqual(
-            list(parts), ["123"],
+            list(parts),
+            ["123"],
         )
 
     def test_long_seq(self):
         parts = chunk_seq("abcdefghijklmnop", 8)
 
         self.assertEqual(
-            list(parts), ["abcdefgh", "ijklmnop"],
+            list(parts),
+            ["abcdefgh", "ijklmnop"],
         )
 
     def test_uneven_parts(self):
         parts = chunk_seq("abcdefghijklmnop", 5)
 
         self.assertEqual(
-            list(parts), ["abcde", "fghij", "klmno", "p"],
+            list(parts),
+            ["abcde", "fghij", "klmno", "p"],
         )
 
     def test_empty_input(self):
         parts = chunk_seq([], 5)
 
         self.assertEqual(
-            list(parts), [],
+            list(parts),
+            [],
         )
 
 
diff --git a/tests/util/test_stream_change_cache.py b/tests/util/test_stream_change_cache.py

index 13b753e367..9ed01f7e0c 100644
--- a/tests/util/test_stream_change_cache.py
+++ b/tests/util/test_stream_change_cache.py
@@ -70,7 +70,8 @@ class StreamChangeCacheTests(unittest.HomeserverTestCase):
         self.assertTrue("user@foo.com" not in cache._entity_to_key)
 
         self.assertEqual(
-            cache.get_all_entities_changed(2), ["bar@baz.net", "user@elsewhere.org"],
+            cache.get_all_entities_changed(2),
+            ["bar@baz.net", "user@elsewhere.org"],
         )
         self.assertIsNone(cache.get_all_entities_changed(1))
 
@@ -80,7 +81,8 @@ class StreamChangeCacheTests(unittest.HomeserverTestCase):
             {"bar@baz.net", "user@elsewhere.org"}, set(cache._entity_to_key)
         )
         self.assertEqual(
-            cache.get_all_entities_changed(2), ["user@elsewhere.org", "bar@baz.net"],
+            cache.get_all_entities_changed(2),
+            ["user@elsewhere.org", "bar@baz.net"],
         )
         self.assertIsNone(cache.get_all_entities_changed(1))
 
@@ -222,7 +224,8 @@ class StreamChangeCacheTests(unittest.HomeserverTestCase):
         # Query a subset of the entries mid-way through the stream. We should
         # only get back the subset.
         self.assertEqual(
-            cache.get_entities_changed(["bar@baz.net"], stream_pos=2), {"bar@baz.net"},
+            cache.get_entities_changed(["bar@baz.net"], stream_pos=2),
+            {"bar@baz.net"},
         )
 
     def test_max_pos(self):