From c15a8449062e9e24bffc03942664e4d5f74bbbc4 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 11:34:10 +0800
Subject: [PATCH 1/9] Remove netCDF4 comment

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

diff --git a/pyproject.toml b/pyproject.toml
index 9fdc121af..5a5e19d1d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,7 +23,7 @@ dependencies = [
   "cftime >=1.6.3",
   "numpy >=2.1.0",
   "dask >=2024.5.1",
-  "netCDF4 >=1.7.2", # TODO: should we use h5netcdf here instead of netCDF4?
+  "netCDF4 >=1.7.2",
   "zarr >=3",
   "tqdm >=4.50.0",
   "xarray >=2024.5.0",

From dcdb0e4a06ac75e58e55dcf45d0695217b789c88 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 11:39:03 +0800
Subject: [PATCH 2/9] Remove comment about `pytest docs/examples`

This folder of scripts doesnt exist in v4
---
 pyproject.toml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pyproject.toml b/pyproject.toml
index 5a5e19d1d..55fcbb45e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -53,7 +53,6 @@ local_scheme = "no-local-version"
 [tool.pytest.ini_options]
 addopts = ["--strict-config", "--strict-markers"]
 xfail_strict = true
-# testpaths = ["tests", "docs/examples"] # TODO v4: Re-enable once examples are back/fixed
 testpaths = ["tests"]
 python_files = ["test_*.py", "example_*.py", "*tutorial*"]
 minversion = "7"

From 9ec86847b4a15daa004047d766daa96101d1d669 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 12:47:22 +0800
Subject: [PATCH 3/9] Move test_reprs.py to v4 test suite

---
 pixi.toml              |   3 ++
 tests-v3/test_reprs.py | 115 -----------------------------------------
 tests/test_reprs.py    |  36 +++++++++++++
 3 files changed, 39 insertions(+), 115 deletions(-)
 delete mode 100644 tests-v3/test_reprs.py
 create mode 100644 tests/test_reprs.py

diff --git a/pixi.toml b/pixi.toml
index a87fff64f..f9f3e5706 100644
--- a/pixi.toml
+++ b/pixi.toml
@@ -83,6 +83,9 @@ pytest-cov = "*"
 pytest-reportlog = "*"
 pytest-timeout = "*"
 
+[feature.test.pypi-dependencies]
+re-assert = "*"
+
 [feature.test.tasks]
 tests = { cmd = "pytest", description = "Run the test suite." }
 tests-flaky = { cmd = "pytest -m 'flaky' --run-flaky-tests", description = "Run only flaky tests." }
diff --git a/tests-v3/test_reprs.py b/tests-v3/test_reprs.py
deleted file mode 100644
index 18407e583..000000000
--- a/tests-v3/test_reprs.py
+++ /dev/null
@@ -1,115 +0,0 @@
-import re
-from datetime import timedelta
-from typing import Any
-
-import numpy as np
-
-import parcels
-from parcels import Grid, ParticleFile, Variable
-from parcels.grid import RectilinearGrid
-from tests.utils import create_fieldset_unit_mesh, create_simple_pset
-
-
-def assert_simple_repr(class_: type, kwargs: dict[str, Any]):
-    """Test that the repr of an object contains all the arguments. This only works for objects where the repr matches the calling signature."""
-    obj = class_(**kwargs)
-    obj_repr = repr(obj)
-
-    for param in kwargs.keys():
-        assert param in obj_repr
-        # skip `assert repr(value) in obj_repr` as this is not always true if init does processing on the value
-    assert class_.__name__ in obj_repr
-
-
-def valid_indentation(s: str) -> bool:
-    """Make sure that all lines in string is indented with a multiple of 4 spaces."""
-    if s.startswith(" "):
-        return False
-
-    lines = s.split("\n")
-    for line in lines:
-        line = re.sub("^( {4})+", "", line)
-        if line.startswith(" "):
-            return False
-    return True
-
-
-def test_check_indentation():
-    valid = """
-test
-    test
-test
-    test
-        test
-    test"""
-    assert valid_indentation(valid)
-    invalid = """
-test
-    test
- invalid!
-"""
-    assert not valid_indentation(invalid)
-
-
-def test_particletype_repr():
-    kwargs = dict(pclass=parcels.Particle)
-    assert_simple_repr(parcels.particle.ParticleType, kwargs)
-
-
-def test_grid_repr():
-    """Test arguments are in the repr of a Grid object"""
-    kwargs = dict(lon=np.array([1, 2, 3]), lat=np.array([4, 5, 6]), time=None, mesh="spherical")
-    assert_simple_repr(Grid, kwargs)
-
-
-def test_variable_repr():
-    """Test arguments are in the repr of the Variable object."""
-    kwargs = dict(name="test", dtype=np.float32, initial=0, to_write=False)
-    assert_simple_repr(Variable, kwargs)
-
-
-def test_rectilineargrid_repr():
-    """
-    Test arguments are in the repr of a RectilinearGrid object.
-
-    Mainly to test inherited repr is correct.
-    """
-    kwargs = dict(lon=np.array([1, 2, 3]), lat=np.array([4, 5, 6]), time=None, mesh="spherical")
-    assert_simple_repr(RectilinearGrid, kwargs)
-
-
-def test_particlefile_repr():
-    pset = create_simple_pset()
-    kwargs = dict(
-        name="file.zarr", particleset=pset, outputdt=timedelta(hours=1), chunks=None, create_new_zarrfile=False
-    )
-    assert_simple_repr(ParticleFile, kwargs)
-
-
-def test_field_repr():
-    field = create_fieldset_unit_mesh().U
-    assert valid_indentation(repr(field))
-
-
-def test_vectorfield_repr():
-    field = create_fieldset_unit_mesh().UV
-    assert isinstance(field, parcels.VectorField)
-    assert valid_indentation(repr(field))
-
-
-def test_fieldset_repr():
-    fieldset = create_fieldset_unit_mesh()
-    assert valid_indentation(repr(fieldset))
-
-
-def test_particleset_repr():
-    pset = create_simple_pset()
-    valid_indentation(repr(pset))
-
-    pset = create_simple_pset(n=15)
-    valid_indentation(repr(pset))
-
-
-def capture(s):
-    with open("file.txt", "a") as f:
-        f.write(s)
diff --git a/tests/test_reprs.py b/tests/test_reprs.py
new file mode 100644
index 000000000..04679addf
--- /dev/null
+++ b/tests/test_reprs.py
@@ -0,0 +1,36 @@
+import numpy as np
+from re_assert import Matches
+
+from parcels import Particle, ParticleFile, ParticleSet
+
+
+def test_particlefile_repr(tmp_parquet):
+    pfile_repr = repr(ParticleFile(tmp_parquet, outputdt=np.timedelta64(1, "s")))
+    match = Matches(
+        r"""\<ParticleFile\>
+    path                : .*
+    outputdt            : 1.0
+    metadata            : .*""",
+    )
+    match.assert_matches(pfile_repr)
+    # assert_simple_repr(ParticleFile, kwargs)
+
+
+def test_field_repr(fieldset):
+    Matches(r"Field\(name=.*, model=.*\)").assert_matches(repr(fieldset.U))
+
+
+def test_vectorfield_repr(fieldset):
+    Matches(r"\<.*VectorField object at.*\>").assert_matches(repr(fieldset.UV))
+
+
+def test_xgrid_repr(fieldset):
+    Matches(r"\<.*XGrid object at.*\>").assert_matches(repr(fieldset.U.grid))
+
+
+def test_fieldset_repr(fieldset):
+    Matches(r"\<.*FieldSet object at.*\>").assert_matches(repr(fieldset))
+
+
+def test_particleset_repr(fieldset):
+    Matches(r"\<.*ParticleSet object at.*\>").assert_matches(repr(ParticleSet(fieldset, pclass=Particle)))

From c9b502ff0fc3f753bdcd809e94b541f365544074 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 12:48:44 +0800
Subject: [PATCH 4/9] Small fixes to reprs

---
 src/parcels/_core/field.py | 2 +-
 src/parcels/_repr_utils.py | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/parcels/_core/field.py b/src/parcels/_core/field.py
index 888cdcca3..ded5993ed 100644
--- a/src/parcels/_core/field.py
+++ b/src/parcels/_core/field.py
@@ -116,7 +116,7 @@ def time_interval(self):  # TODO PR: Remove in favour of referencing model time_
         return self.model.time_interval
 
     def __repr__(self):
-        return f"Field(name={self.name}, model={self.model})"
+        return f"Field(name={self.name!r}, model={self.model})"
 
     @property
     def interp_method(self):
diff --git a/src/parcels/_repr_utils.py b/src/parcels/_repr_utils.py
index 9e2c828c5..a64dc103a 100644
--- a/src/parcels/_repr_utils.py
+++ b/src/parcels/_repr_utils.py
@@ -138,8 +138,7 @@ def particlefile_repr(pfile: Any) -> str:
     out = f"""<{type(pfile).__name__}>
     path                : {pfile.path}
     outputdt            : {pfile.outputdt!r}
-    metadata            :
-{_format_list_items_multiline(pfile.metadata, level=2, with_brackets=False)}
+    metadata            : {_format_list_items_multiline(pfile.metadata, level=2, with_brackets=False)}
 """
     return textwrap.dedent(out).strip()
 

From c8cb78051987ad1af69870478359349e47791e5e Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 12:49:01 +0800
Subject: [PATCH 5/9] Remove mentions of legacy folders

---
 docs/conf.py   | 1 -
 pyproject.toml | 5 -----
 2 files changed, 6 deletions(-)

diff --git a/docs/conf.py b/docs/conf.py
index feb8b5f4c..75852a08e 100755
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -121,7 +121,6 @@
     "_build",
     "jupyter_execute",
     "**.ipynb_checkpoints",
-    "user_guide/examples_v3",
     ".jupyter_cache",
 ]
 
diff --git a/pyproject.toml b/pyproject.toml
index 55fcbb45e..9b2cbbdf0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -100,11 +100,6 @@ select = [
   "NPY201", # numpy 2 deprecations
 ]
 
-exclude = [
-  "tests-v3/**",
-  'docs/user_guide/examples_v3/**',
-] # TODO v4: Remove once folders are gone
-
 ignore = [
   # # Rules intentionally excluded
   # line too long (82 > 79 characters)

From a2fb915a0fb6d292f7dae7aaae1a9e91a194be72 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 13:04:31 +0800
Subject: [PATCH 6/9] Remove outdated comment

This now works with xdim=1 and ydim=1 (when it comes to ingestion of SGRID, and when testing alongside `test_moving_eddy`).

xref https://github.com/Parcels-code/Parcels/pull/2135/changes#r2256749529
---
 src/parcels/_datasets/structured/generated.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/parcels/_datasets/structured/generated.py b/src/parcels/_datasets/structured/generated.py
index 7eba61f55..05ad96dd6 100644
--- a/src/parcels/_datasets/structured/generated.py
+++ b/src/parcels/_datasets/structured/generated.py
@@ -91,7 +91,7 @@ def radial_rotation_dataset(xdim=200, ydim=200):  # Define 2D flat, square field
     )
 
 
-def moving_eddy_dataset(xdim=2, ydim=2):  # TODO check if this also works with xdim=1, ydim=1
+def moving_eddy_dataset(xdim=2, ydim=2):
     """Create a dataset with an eddy moving in time. Note that there is no spatial variation in the flow."""
     f, u_0, u_g = 1.0e-4, 0.3, 0.04  # Some constants
 

From 2328eac7da93387dcf9cf8fd6ddc4ab7b110f601 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 13:07:41 +0800
Subject: [PATCH 7/9] Remove outdated comment

---
 src/parcels/_repr_utils.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/parcels/_repr_utils.py b/src/parcels/_repr_utils.py
index a64dc103a..1386761dc 100644
--- a/src/parcels/_repr_utils.py
+++ b/src/parcels/_repr_utils.py
@@ -44,7 +44,6 @@ def fieldset_repr(fieldset: FieldSet) -> str:
     return textwrap.dedent(out).strip()
 
 
-# TODO add land_value here after HG #2451 is merged
 def field_repr(field: Field, level: int = 0) -> str:
     """Return a pretty repr for Field"""
     with xr.set_options(display_expand_data=False):

From 920d457251b0fdbf775bcded93797cdf16215b3d Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 13:07:48 +0800
Subject: [PATCH 8/9] Update TODO comment

---
 src/parcels/_typing.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/parcels/_typing.py b/src/parcels/_typing.py
index dd98afc44..7f1540e82 100644
--- a/src/parcels/_typing.py
+++ b/src/parcels/_typing.py
@@ -60,7 +60,7 @@ def _validate_against_pure_literal(value, typing_literal):
 
     Can't be used with ``Literal[...] | None`` etc. as its not a pure literal.
     """
-    # TODO remove once https://github.com/pydata/xarray/issues/11209 is resolved - Xarray objects don't work normally in `in` statements
+    # Xarray objects don't work normally in `in` statements - see https://github.com/pydata/xarray/issues/11209 (this is unlikely to be resolved anytime soon)
     if _is_xarray_object(value):
         raise ValueError(f"Invalid input type {type(value)}")
 

From b04db584abb56ed310b13432fe6e51f883db70e0 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 2 Sep 2026 13:15:58 +0800
Subject: [PATCH 9/9] Split test_reprs.py into respective files

---
 tests/test_field.py        |  9 +++++++++
 tests/test_fieldset.py     |  5 +++++
 tests/test_particlefile.py | 15 ++++++++++++++-
 tests/test_particleset.py  |  5 +++++
 tests/test_reprs.py        | 36 ------------------------------------
 tests/test_xgrid.py        |  5 +++++
 6 files changed, 38 insertions(+), 37 deletions(-)
 delete mode 100644 tests/test_reprs.py

diff --git a/tests/test_field.py b/tests/test_field.py
index 3050aba89..924335a86 100644
--- a/tests/test_field.py
+++ b/tests/test_field.py
@@ -2,6 +2,7 @@
 
 import numpy as np
 import pytest
+from re_assert import Matches
 
 from parcels import Field, VectorField
 from parcels._core.fieldset import FieldSet
@@ -39,6 +40,14 @@ def test_field_init_param_types():
         Field(name="while", model=model)
 
 
+def test_field_repr(fieldset):
+    Matches(r"Field\(name=.*, model=.*\)").assert_matches(repr(fieldset.U))
+
+
+def test_vectorfield_repr(fieldset):
+    Matches(r"\<.*VectorField object at.*\>").assert_matches(repr(fieldset.UV))
+
+
 # TODO: Move to test_model.py ?
 def test_field_init_fail_on_float_time_dim():
     """Test that accessing time_interval fails when dataset has float time dimension.
diff --git a/tests/test_fieldset.py b/tests/test_fieldset.py
index b1b6b16f6..f83f8b126 100644
--- a/tests/test_fieldset.py
+++ b/tests/test_fieldset.py
@@ -7,6 +7,7 @@
 import pandas as pd
 import pytest
 import xarray as xr
+from re_assert import Matches
 
 import parcels.tutorial
 import tests
@@ -40,6 +41,10 @@ def test_fieldset_init_wrong_types():
         FieldSet([1.0, 2.0, 3.0])
 
 
+def test_fieldset_repr(fieldset):
+    Matches(r"\<.*FieldSet object at.*\>").assert_matches(repr(fieldset))
+
+
 def test_fieldset_add_context(fieldset):
     fieldset.add_context("test_context", 1.0)
     assert fieldset.test_context == 1.0
diff --git a/tests/test_particlefile.py b/tests/test_particlefile.py
index 38645de8d..39646a51d 100755
--- a/tests/test_particlefile.py
+++ b/tests/test_particlefile.py
@@ -9,11 +9,13 @@
 import pyarrow.parquet as pq
 import pytest
 import xarray as xr
+from re_assert import Matches
 
 import parcels.tutorial
 from parcels import (
     Field,
     FieldSet,
+    Particle,
     ParticleFile,
     ParticleSet,
     ParticleSetWarning,
@@ -21,7 +23,7 @@
     Variable,
     convert,
 )
-from parcels._core.particle import Particle, get_default_particle
+from parcels._core.particle import get_default_particle
 from parcels._core.particlefile import get_schema
 from parcels._core.utils.time import TimeInterval, timedelta_to_float
 from parcels._datasets.structured.generated import peninsula_dataset
@@ -30,6 +32,17 @@
 from tests.common_kernels import DoNothing
 
 
+def test_particlefile_repr(tmp_parquet):
+    pfile_repr = repr(ParticleFile(tmp_parquet, outputdt=np.timedelta64(1, "s")))
+    match = Matches(
+        r"""\<ParticleFile\>
+    path                : .*
+    outputdt            : 1.0
+    metadata            : .*""",
+    )
+    match.assert_matches(pfile_repr)
+
+
 def test_metadata(fieldset, tmp_parquet):
     pset = ParticleSet(fieldset, pclass=Particle, x=0, y=0)
 
diff --git a/tests/test_particleset.py b/tests/test_particleset.py
index d0721b7ed..5166c6c8c 100644
--- a/tests/test_particleset.py
+++ b/tests/test_particleset.py
@@ -5,6 +5,7 @@
 import numpy as np
 import pytest
 import xarray as xr
+from re_assert import Matches
 
 from parcels import (
     FieldSet,
@@ -35,6 +36,10 @@ def test_create_empty_pset(fieldset):
     assert pset.size == 0
 
 
+def test_particleset_repr(fieldset):
+    Matches(r"\<.*ParticleSet object at.*\>").assert_matches(repr(ParticleSet(fieldset, pclass=Particle)))
+
+
 @pytest.mark.parametrize("offset", [0, 1, 200])
 def test_pset_with_pids(fieldset, offset, npart=100):
     lon = np.linspace(0, 1, npart)
diff --git a/tests/test_reprs.py b/tests/test_reprs.py
deleted file mode 100644
index 04679addf..000000000
--- a/tests/test_reprs.py
+++ /dev/null
@@ -1,36 +0,0 @@
-import numpy as np
-from re_assert import Matches
-
-from parcels import Particle, ParticleFile, ParticleSet
-
-
-def test_particlefile_repr(tmp_parquet):
-    pfile_repr = repr(ParticleFile(tmp_parquet, outputdt=np.timedelta64(1, "s")))
-    match = Matches(
-        r"""\<ParticleFile\>
-    path                : .*
-    outputdt            : 1.0
-    metadata            : .*""",
-    )
-    match.assert_matches(pfile_repr)
-    # assert_simple_repr(ParticleFile, kwargs)
-
-
-def test_field_repr(fieldset):
-    Matches(r"Field\(name=.*, model=.*\)").assert_matches(repr(fieldset.U))
-
-
-def test_vectorfield_repr(fieldset):
-    Matches(r"\<.*VectorField object at.*\>").assert_matches(repr(fieldset.UV))
-
-
-def test_xgrid_repr(fieldset):
-    Matches(r"\<.*XGrid object at.*\>").assert_matches(repr(fieldset.U.grid))
-
-
-def test_fieldset_repr(fieldset):
-    Matches(r"\<.*FieldSet object at.*\>").assert_matches(repr(fieldset))
-
-
-def test_particleset_repr(fieldset):
-    Matches(r"\<.*ParticleSet object at.*\>").assert_matches(repr(ParticleSet(fieldset, pclass=Particle)))
diff --git a/tests/test_xgrid.py b/tests/test_xgrid.py
index c22437281..2d28d4aef 100644
--- a/tests/test_xgrid.py
+++ b/tests/test_xgrid.py
@@ -5,6 +5,7 @@
 import pytest
 import xarray as xr
 from numpy.testing import assert_allclose
+from re_assert import Matches
 
 from parcels import FieldSet
 from parcels._core.index_search import (
@@ -56,6 +57,10 @@ def test_grid_init_param_types(ds):
         XGrid.from_dataset(ds, mesh="invalid")
 
 
+def test_xgrid_repr(fieldset):
+    Matches(r"\<.*XGrid object at.*\>").assert_matches(repr(fieldset.U.grid))
+
+
 @pytest.mark.parametrize("ds, attr, expected", test_cases)
 def test_xgrid_properties_ground_truth(ds, attr, expected):
     grid = FieldSet.from_sgrid_conventions(ds, mesh="flat").data_g.grid