fix silenced unit conversion bugs

yt/data_objects/tests/test_numpy_ops.py

@@ -90,6 +90,8 @@ def test_mean_sum_integrate():
 
 
 def test_min_max():
+    fields = ("density", "temperature")
+    units = ("g/cm**3", "K")
     for nprocs in [-1, 1, 2, 16]:
         fields = ["density", "temperature"]
         units = ["g/cm**3", "K"]

yt/fields/field_info_container.py

@@ -2,7 +2,6 @@
 from typing import Optional, Tuple
 
 import numpy as np
-from unyt.exceptions import UnitConversionError
 
 from yt._maintenance.deprecation import issue_deprecation_warning
 from yt.fields.field_exceptions import NeedsConfiguration
@@ -588,7 +587,7 @@ def check_derived_fields(self, fields_to_check=None):
             AttributeError,
             KeyError,
             # code smells -> those are very likely bugs
-            UnitConversionError,  # solved in GH PR 2897 ?
+            # UnitConversionError,  # solved in GH PR 2897 ?
             # RecursionError is clearly a bug, and was already solved once
             # in GH PR 2851
             RecursionError,

yt/fields/fluid_fields.py

@@ -1,4 +1,5 @@
 import numpy as np
+from unyt.exceptions import UnitConversionError
 
 from yt.funcs import mylog
 from yt.geometry.geometry_handler import is_curvilinear
@@ -172,7 +173,16 @@ def _pressure(field, data):
     )
 
     def _kT(field, data):
-        return (pc.kboltz * data[ftype, "temperature"]).in_units("keV")
+        ret = pc.kboltz * data[ftype, "temperature"]
+        try:
+            return ret.in_units("keV")
+        except UnitConversionError as err:
+            # Chances are this is a non-weighted projection object and the
+            # 'temperature' field is expressed in K*cm
+            # see GH PR 2897
+            raise NotImplementedError(
+                "Can not define a kT field if temperature can not be converted to 'K'. "
+            ) from err
 
     registry.add_field(
         (ftype, "kT"),

yt/fields/vector_operations.py

@@ -170,10 +170,10 @@ def create_vector_fields(registry, basename, field_units, ftype="gas", slice_inf
     xn, yn, zn = [(ftype, f"{basename}_{ax}") for ax in "xyz"]
 
     # Is this safe?
-    if registry.ds.dimensionality < 3:
-        zn = ("index", "zeros")
-    if registry.ds.dimensionality < 2:
-        yn = ("index", "zeros")
+    # if registry.ds.dimensionality < 3:
+    #    zn = ("index", "zeros")
+    # if registry.ds.dimensionality < 2:
+    #    yn = ("index", "zeros")
 
     create_relative_field(
         registry,

yt/testing.py

@@ -7,10 +7,11 @@
 import shutil
 import tempfile
 import unittest
+import warnings
 
 import matplotlib
 import numpy as np
-from more_itertools import always_iterable
+from more_itertools import always_iterable, zip_equal
 from numpy.random import RandomState
 from unyt.exceptions import UnitOperationError
 
@@ -228,6 +229,17 @@ def fake_random_ds(
 ):
     from yt.loaders import load_uniform_grid
 
+    if fields is None:
+        fields = ("density", "velocity_x", "velocity_y", "velocity_z")
+        if units is not None:
+            warnings.warn(
+                "Received `units` keyword argument but no `fields`, "
+                "ignoring `units`."
+            )
+        units = ("g/cm**3", "cm/s", "cm/s", "cm/s")
+    if units is None:
+        raise ValueError("missing required keyword argument `units`.")
+
     prng = RandomState(0x4D3D3D3)
     if not is_sequence(ndims):
         ndims = [ndims, ndims, ndims]
@@ -259,7 +271,7 @@ def fake_random_ds(
         else:
             offsets.append(0.0)
     data = {}
-    for field, offset, u in zip(fields, offsets, units):
+    for field, offset, u in zip_equal(fields, offsets, units):
         v = (prng.random_sample(ndims) - offset) * peak_value
         if field[0] == "all":
             v = v.ravel()

yt/utilities/lib/tests/test_geometry_utils.py

@@ -14,7 +14,6 @@
 
 _fields = ("density", "velocity_x", "velocity_y", "velocity_z")
 _units = ("g/cm**3", "cm/s", "cm/s", "cm/s")
-
 # TODO: error compact/spread bits for incorrect size
 # TODO: test msdb for [0,0], [1,1], [2,2] etc.
 

yt/visualization/volume_rendering/tests/test_lenses.py

@@ -30,6 +30,7 @@ def setUp(self):
             self.curdir, self.tmpdir = None, None
 
         self.field = ("gas", "density")
+        # TODO: Check this (I wrote this as self.field[1] in an earlier draft)
         self.ds = fake_random_ds(32, fields=(self.field,), units=("g/cm**3",))
         self.ds.index