integration tests for htex vs code serialization caches

it would be nice to parameterise these rather than have two distinct copies

the reason for testing with alternate mode too is because that has monitoring
on, for exmaple, which does different wrapping and has caused cache failures
in the past.

most immediately i'm investigating this because inside desc I am seeing some
cache failures that are unexpected...

parsl/tests/test_serialization/test_htex_alternate_cache.py

@@ -0,0 +1,57 @@
+import parsl
+import pytest
+
+from typing import Any
+
+from parsl.serialize.facade import methods_for_code
+
+from parsl.tests.configs.htex_local_alternate import fresh_config as local_config
+
+
+@parsl.python_app
+def f(x):
+    return x + 1
+
+
+@pytest.mark.local
+def test_caching() -> None:
+    # for future serializer devs: if this is failing because you added another
+    # code serializer, you'll also probably need to re-think what is being tested
+    # about serialization caching here.
+    assert len(methods_for_code) == 1
+
+    serializer = methods_for_code[b'C2']
+
+    # force type to Any here because a serializer method coming from
+    # methods_for_code doesn't statically have any cache management
+    # methods on itself such as cache_clear or cache_info.
+    serialize_method: Any = serializer.serialize
+
+    serialize_method.cache_clear()
+
+    assert serialize_method.cache_info().hits == 0
+    assert serialize_method.cache_info().misses == 0
+    assert serialize_method.cache_info().currsize == 0
+
+    assert f(7).result() == 8
+
+    # the code serializer cache should now contain only a (probably wrapped) f ...
+    assert serialize_method.cache_info().currsize == 1
+
+    # ... which was not already in the cache.
+    assert serialize_method.cache_info().misses == 1
+    assert serialize_method.cache_info().hits == 0
+
+    assert f(100).result() == 101
+
+    # this time round, we should have got a single cache hit...
+    assert serialize_method.cache_info().hits == 1
+    assert serialize_method.cache_info().misses == 1
+    assert serialize_method.cache_info().currsize == 1
+
+    assert f(200).result() == 201
+
+    # this time round, we should have got another single cache hit...
+    assert serialize_method.cache_info().hits == 2
+    assert serialize_method.cache_info().misses == 1
+    assert serialize_method.cache_info().currsize == 1

parsl/tests/test_serialization/test_htex_cache.py

@@ -0,0 +1,57 @@
+import parsl
+import pytest
+
+from typing import Any
+
+from parsl.serialize.facade import methods_for_code
+
+from parsl.tests.configs.htex_local import fresh_config as local_config
+
+
+@parsl.python_app
+def f(x):
+    return x + 1
+
+
+@pytest.mark.local
+def test_caching() -> None:
+    # for future serializer devs: if this is failing because you added another
+    # code serializer, you'll also probably need to re-think what is being tested
+    # about serialization caching here.
+    assert len(methods_for_code) == 1
+
+    serializer = methods_for_code[b'C2']
+
+    # force type to Any here because a serializer method coming from
+    # methods_for_code doesn't statically have any cache management
+    # methods on itself such as cache_clear or cache_info.
+    serialize_method: Any = serializer.serialize
+
+    serialize_method.cache_clear()
+
+    assert serialize_method.cache_info().hits == 0
+    assert serialize_method.cache_info().misses == 0
+    assert serialize_method.cache_info().currsize == 0
+
+    assert f(7).result() == 8
+
+    # the code serializer cache should now contain only a (probably wrapped) f ...
+    assert serialize_method.cache_info().currsize == 1
+
+    # ... which was not already in the cache.
+    assert serialize_method.cache_info().misses == 1
+    assert serialize_method.cache_info().hits == 0
+
+    assert f(100).result() == 101
+
+    # this time round, we should have got a single cache hit...
+    assert serialize_method.cache_info().hits == 1
+    assert serialize_method.cache_info().misses == 1
+    assert serialize_method.cache_info().currsize == 1
+
+    assert f(200).result() == 201
+
+    # this time round, we should have got another single cache hit...
+    assert serialize_method.cache_info().hits == 2
+    assert serialize_method.cache_info().misses == 1
+    assert serialize_method.cache_info().currsize == 1