From e582892b131d8a769d60bb4c196eca936d6772ca Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Mon, 18 May 2026 10:13:30 +0200
Subject: [PATCH 1/6] Rename file

---
 tests/validation/__init__.py                     | 0
 tests/{uxvalidation.py => validation/test_ux.py} | 0
 2 files changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 tests/validation/__init__.py
 rename tests/{uxvalidation.py => validation/test_ux.py} (100%)

diff --git a/tests/validation/__init__.py b/tests/validation/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/uxvalidation.py b/tests/validation/test_ux.py
similarity index 100%
rename from tests/uxvalidation.py
rename to tests/validation/test_ux.py

From 8abea1e21334d41d751d8b65ecaaaf67e7503b04 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Mon, 18 May 2026 10:16:01 +0200
Subject: [PATCH 2/6] Skip validation and flaky tests by default

Uses this SO trick for skipping marked tests by default

https://stackoverflow.com/questions/66315234/exclude-some-tests-by-default/69185648#69185648
---
 pixi.toml                   |  2 +-
 pyproject.toml              |  1 +
 tests/conftest.py           | 14 ++++++++++++++
 tests/validation/test_ux.py |  2 ++
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/pixi.toml b/pixi.toml
index d2331b5761..e19c8b68f6 100644
--- a/pixi.toml
+++ b/pixi.toml
@@ -79,7 +79,7 @@ pytest-html = "*"
 pytest-cov = "*"
 
 [feature.test.tasks]
-tests = { cmd = "pytest -m 'not flaky'", description = "Run the test suite." }
+tests = { cmd = "pytest", description = "Run the test suite." }
 tests-notebooks = { cmd = "pytest --nbval-lax docs/user_guide/examples", description = "Run the user guide example notebooks as tests." }
 
 
diff --git a/pyproject.toml b/pyproject.toml
index d00ac65f5a..182a5d00f3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -60,6 +60,7 @@ minversion = "7"
 markers = [ # can be skipped by doing `pytest -m "not slow"` etc.
   "flaky: flaky tests",
   "slow: slow tests",
+  "validation: validation tests (skipped by default, run with `-m validation`)",
   "v4alpha: failing tests that should work for v4alpha",
   "v4future: failing tests that should work for a future release of v4",
   "v4remove: failing tests that should probably be removed later",
diff --git a/tests/conftest.py b/tests/conftest.py
index 0fd949880f..ac29a34a5f 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,5 +1,19 @@
 import pytest
 
+SKIP_BY_DEFAULT = {"validation", "flaky"}
+
+
+def pytest_collection_modifyitems(config, items):
+    if not config.getoption("-m"):
+        for item in items:
+            print(item.keywords)
+            skip_by_default = list(SKIP_BY_DEFAULT & set(item.keywords))
+            if skip_by_default:
+                skip_marker = skip_by_default[0]  # get first marker in case of multiple
+                item.add_marker(
+                    pytest.mark.skip(reason=f"{skip_marker} tests skipped by default, use `-m {skip_marker}` to run")
+                )
+
 
 @pytest.fixture
 def tmp_parquet(tmp_path):
diff --git a/tests/validation/test_ux.py b/tests/validation/test_ux.py
index 9d160345f3..0658d88d41 100644
--- a/tests/validation/test_ux.py
+++ b/tests/validation/test_ux.py
@@ -36,6 +36,8 @@
     AdvectionRK4_3D,
 )
 
+pytestmark = pytest.mark.validation
+
 # Uniform translation parameters
 T1_1_U0 = 0.001
 T1_1_V0 = 0.0005

From 0ff9fe14b64b4db34e0d5784f2d644a77a7c9a39 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Mon, 18 May 2026 11:44:14 +0200
Subject: [PATCH 3/6] Add pixi tasks

---
 .github/workflows/ci.yml | 4 ++--
 pixi.toml                | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index de34d104a6..d51af81c6b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -127,7 +127,7 @@ jobs:
           name: Unittest report ${{ matrix.os }}-${{ matrix.pixi-environment }}
           path: ${{ env.COVERAGE_REPORT }}
   flaky-unit-test:
-    name: "Flaky unit tests: ${{ matrix.os }} | pixi run -e ${{ matrix.pixi-environment }} tests -m 'flaky'"
+    name: "Flaky unit tests: ${{ matrix.os }} | pixi run -e ${{ matrix.pixi-environment }} tests-flaky"
     runs-on: ${{ matrix.os }}-latest
     needs: [cache-pixi-lock]
     permissions:
@@ -165,7 +165,7 @@ jobs:
       - name: Unit test
         id: unit-test
         run: |
-          pixi run -e ${{ matrix.pixi-environment }} tests -m 'flaky' -v -s --cov=parcels --cov-report=xml --html="${COVERAGE_REPORT}" --self-contained-html
+          pixi run -e ${{ matrix.pixi-environment }} tests-flaky -v -s --cov=parcels --cov-report=xml --html="${COVERAGE_REPORT}" --self-contained-html
       # explicitly save the cache so it gets updated, also do this even if it fails.
       - name: Save cached hypothesis directory
         id: save-hypothesis-cache
diff --git a/pixi.toml b/pixi.toml
index e19c8b68f6..6568b39b7a 100644
--- a/pixi.toml
+++ b/pixi.toml
@@ -80,6 +80,8 @@ pytest-cov = "*"
 
 [feature.test.tasks]
 tests = { cmd = "pytest", description = "Run the test suite." }
+tests-flaky = { cmd = "pytest -m 'flaky'", description = "Run flaky tests." }
+tests-validation = { cmd = "pytest -m 'flaky'", description = "Run validation tests." }
 tests-notebooks = { cmd = "pytest --nbval-lax docs/user_guide/examples", description = "Run the user guide example notebooks as tests." }
 
 

From 68148fe5edad780e7b20bcd989fc440237f0f83b Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Mon, 18 May 2026 11:47:45 +0200
Subject: [PATCH 4/6] Fix validation tests

---
 pixi.toml                   | 2 +-
 tests/validation/test_ux.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/pixi.toml b/pixi.toml
index 6568b39b7a..a138098f73 100644
--- a/pixi.toml
+++ b/pixi.toml
@@ -81,7 +81,7 @@ pytest-cov = "*"
 [feature.test.tasks]
 tests = { cmd = "pytest", description = "Run the test suite." }
 tests-flaky = { cmd = "pytest -m 'flaky'", description = "Run flaky tests." }
-tests-validation = { cmd = "pytest -m 'flaky'", description = "Run validation tests." }
+tests-validation = { cmd = "pytest -m 'validation'", description = "Run validation tests." }
 tests-notebooks = { cmd = "pytest --nbval-lax docs/user_guide/examples", description = "Run the user guide example notebooks as tests." }
 
 
diff --git a/tests/validation/test_ux.py b/tests/validation/test_ux.py
index 0658d88d41..7771366f6b 100644
--- a/tests/validation/test_ux.py
+++ b/tests/validation/test_ux.py
@@ -69,7 +69,7 @@
 )
 @pytest.mark.parametrize("integrator", [AdvectionEE, AdvectionRK4], ids=["EE", "RK4"])
 def test_uniform_translation_exact(dataset_fn, integrator):
-    ds = dataset_fn(nx=20, U0=T1_1_U0, V0=T1_1_V0)
+    ds = dataset_fn(nx=20, u0=T1_1_U0, v0=T1_1_V0)
     fieldset = parcels.FieldSet.from_ugrid_conventions(ds, mesh="flat")
 
     pset = parcels.ParticleSet(fieldset, lon=[T1_1_LON0], lat=[T1_1_LAT0])

From 78fbae572187e487b79492a78a16ed5f5a219875 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Mon, 18 May 2026 12:55:07 +0200
Subject: [PATCH 5/6] Update marker description

---
 pyproject.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pyproject.toml b/pyproject.toml
index 182a5d00f3..a8e0b16642 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -58,9 +58,9 @@ testpaths = ["tests"]
 python_files = ["test_*.py", "example_*.py", "*tutorial*"]
 minversion = "7"
 markers = [ # can be skipped by doing `pytest -m "not slow"` etc.
-  "flaky: flaky tests",
   "slow: slow tests",
   "validation: validation tests (skipped by default, run with `-m validation`)",
+  "flaky: flaky tests (skipped by default, run with `-m flaky`)",
   "v4alpha: failing tests that should work for v4alpha",
   "v4future: failing tests that should work for a future release of v4",
   "v4remove: failing tests that should probably be removed later",

From 8e92fe718ce103e6f966bd1d8afe7468d3163da0 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Mon, 18 May 2026 12:57:15 +0200
Subject: [PATCH 6/6] Update release checklist

---
 docs/development/maintainer.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/development/maintainer.md b/docs/development/maintainer.md
index d284493a5b..c357dca700 100644
--- a/docs/development/maintainer.md
+++ b/docs/development/maintainer.md
@@ -19,6 +19,7 @@
 
 ## Release checklist
 
+- Run the validation test suite (`pixi run tests-validation`)
 - Go to GitHub, draft new release. Enter name of version and "create new tag" if it doesn't already exist. Click "Generate Release Notes". Currate release notes as needed. Look at a previous version release to match the format (title, header, section organisation etc.)
 - Go to [conda-forge/parcels-feedstock](https://github.com/conda-forge/parcels-feedstock), create a new issue (select the "Bot Commands" issue from the menu) with title `@conda-forge-admin, please update version`. This will prompt a build, otherwise there can be a delay in the build.
   - Approve PR and merge on green