From 72d00bdbab7fe2223e3e978abdbd13d61b85d391 Mon Sep 17 00:00:00 2001
From: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
Date: Thu, 21 Dec 2023 11:12:55 +0000
Subject: [PATCH 1/2] Tests: fix cached point parse contamination between tests

In back-compat mode the cycle point time zone is assumed to be local, whereas in normal mode it is assumed to be UTC. There was contamination of the point parse caching where the time zone would carry over from tests of back-compat vs normal mode
---
 cylc/flow/cycling/iso8601.py        | 16 +++++++++++++---
 tests/integration/test_task_pool.py |  1 -
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/cylc/flow/cycling/iso8601.py b/cylc/flow/cycling/iso8601.py
index 3c8bd3955fa..655c06c2881 100644
--- a/cylc/flow/cycling/iso8601.py
+++ b/cylc/flow/cycling/iso8601.py
@@ -943,12 +943,22 @@ def _interval_parse(interval_string):
 
 def point_parse(point_string: str) -> 'TimePoint':
     """Parse a point_string into a proper TimePoint object."""
-    return _point_parse(point_string, WorkflowSpecifics.DUMP_FORMAT)
+    return _point_parse(
+        point_string,
+        WorkflowSpecifics.DUMP_FORMAT,
+        WorkflowSpecifics.ASSUMED_TIME_ZONE
+    )
 
 
 @lru_cache(10000)
-def _point_parse(point_string, _dump_fmt):
-    """Parse a point_string into a proper TimePoint object."""
+def _point_parse(point_string: str, _dump_fmt, _tz) -> 'TimePoint':
+    """Parse a point_string into a proper TimePoint object.
+
+    Args:
+        point_string: The string to parse.
+        _dump_fmt: Dump format (only used to avoid invalid cache hits).
+        _tz: Cycle point time zone (only used to avoid invalid cache hits).
+    """
     if "%" in WorkflowSpecifics.DUMP_FORMAT:
         # May be a custom not-quite ISO 8601 dump format.
         with contextlib.suppress(IsodatetimeError):
diff --git a/tests/integration/test_task_pool.py b/tests/integration/test_task_pool.py
index 2d13cd3d5c8..c334db83423 100644
--- a/tests/integration/test_task_pool.py
+++ b/tests/integration/test_task_pool.py
@@ -1291,7 +1291,6 @@ async def test_compute_runahead(
             'scheduler': {
                 'allow implicit tasks': 'True',
                 'cycle point format': 'CCYY',
-                'cycle point time zone': 'Z'
             },
             'scheduling': {
                 'initial cycle point': '0001',

From 8b2ac186fd59b14fd478f05b12f28008b60d1dc1 Mon Sep 17 00:00:00 2001
From: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
Date: Thu, 21 Dec 2023 11:17:12 +0000
Subject: [PATCH 2/2] Remove pytest-env

* We were using the pytest-env plugin to run the tests in a non-UTC time zone.
* The pytest-env plugin doesn't work with pytest-xdist so this was being ignored.
* Also due to the way TZ support works in Python, changing the env var whilst Python is running may or may not result in changes.
---
 .github/workflows/test_fast.yml | 10 ++++++++--
 pytest.ini                      |  3 ---
 setup.cfg                       |  1 -
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/test_fast.yml b/.github/workflows/test_fast.yml
index 821760f9e5b..f779924ef90 100644
--- a/.github/workflows/test_fast.yml
+++ b/.github/workflows/test_fast.yml
@@ -20,11 +20,17 @@ jobs:
       fail-fast: false # Don't let a failed MacOS run stop the Ubuntu runs
       matrix:
         os: ['ubuntu-latest']
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.7', '3.8', '3.10', '3.11']
         include:
+          # mac os test
           - os: 'macos-latest'
-            python-version: '3.7'
+            python-version: '3.7'  # oldest supported version
+          # non-utc timezone test
+          - os: 'ubuntu-latest'
+            python-version: '3.9'  # not the oldest, not the most recent version
+            time-zone: 'XXX-09:35'
     env:
+      TZ: ${{ matrix.time-zone }}
       PYTEST_ADDOPTS: --cov --cov-append -n 5 --color=yes
     steps:
       - name: Checkout
diff --git a/pytest.ini b/pytest.ini
index 79cc3b55f54..9be86cb507c 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -32,9 +32,6 @@ testpaths =
     cylc/flow/
     tests/unit/
     tests/integration/
-env =
-    # a weird timezone to check that tests aren't assuming the local timezone
-    # TZ=XXX-09:35
 doctest_optionflags =
     NORMALIZE_WHITESPACE
     IGNORE_EXCEPTION_DETAIL
diff --git a/setup.cfg b/setup.cfg
index 25479541eaf..67ed7ac71c3 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -119,7 +119,6 @@ tests =
     pytest-asyncio>=0.17,!=0.23.*
     pytest-cov>=2.8.0
     pytest-xdist>=2
-    pytest-env>=0.6.2
     pytest>=6
     testfixtures>=6.11.0
     towncrier>=23