Remove mypy exclusion for test_dataarray (#10761)

* Remove mypy exclusion for xarray.tests.test_dataarray

This commit removes test_dataarray from the mypy exclusions list and fixes
all resulting type errors:

- Add type ignores for intentional test cases that verify error handling
- Add type ignore for scipy import fallback to object
- Split test_astype_attrs to handle Variable separately from DataArray/Dataset
  due to different method signatures (Variable.astype doesn't have keep_attrs)
- Add type ignores for MultiIndex.get_level_values calls where names may be None

All tests continue to pass after these changes.

Co-authored-by: Claude <noreply@anthropic.com>

* Update CLAUDE.md to use noreply@anthropic.com for co-authorship

This email format is more likely to be recognized by GitHub for bot/AI
co-authorship attribution.

Co-authored-by: Claude <noreply@anthropic.com>

* Fix mypy unused-ignore errors

Use the established pattern of including unused-ignore in the type ignore
comments for cases where the ignore necessity varies by environment:
- scipy_.py: scipy import is optional, so ignore is unused when scipy is installed
- test_dataarray.py: pandas-stubs versions vary in their MultiIndex.names typing

Co-authored-by: Claude <noreply@anthropic.com>

* Clarify comment about test_astype_attrs split

The split is required for mypy type checking, not due to API differences.
Variable, DataArray, and Dataset don't share a common base class that mypy
recognizes, so when they're in the same list, mypy infers the type as
'object', which lacks the attrs and astype methods.

Co-authored-by: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: max-sixty

CLAUDE.md

@@ -29,4 +29,4 @@ uv run dmypy run  # Type checking with mypy
 - Never post "update" messages, progress reports, or explanatory comments on
   GitHub issues/PRs unless specifically instructed
 - When creating commits, always include a co-authorship trailer:
-  `Co-authored-by: Claude <claude@anthropic.com>`
+  `Co-authored-by: Claude <noreply@anthropic.com>`

pyproject.toml

@@ -190,7 +190,6 @@ check_untyped_defs = false
 module = [
   "xarray.tests.test_coding_times",
   "xarray.tests.test_dask",
-  "xarray.tests.test_dataarray",
   "xarray.tests.test_duck_array_ops",
   "xarray.tests.test_indexing",
   "xarray.tests.test_sparse",

xarray/backends/scipy_.py

@@ -38,7 +38,7 @@
 try:
     from scipy.io import netcdf_file as netcdf_file_base
 except ImportError:
-    netcdf_file_base = object
+    netcdf_file_base = object  # type: ignore[assignment,misc,unused-ignore]  # scipy is optional
 
 
 if TYPE_CHECKING:

xarray/tests/test_dataarray.py

@@ -162,7 +162,7 @@ def test_properties(self) -> None:
         with pytest.raises(ValueError, match=r"must be 1-dimensional"):
             self.ds["foo"].to_index()
         with pytest.raises(AttributeError):
-            self.dv.variable = self.v
+            self.dv.variable = self.v  # type: ignore[misc]
 
     def test_data_property(self) -> None:
         array = DataArray(np.zeros((3, 4)))
@@ -1243,7 +1243,7 @@ def test_head(self) -> None:
             self.dv.isel({dim: slice(5) for dim in self.dv.dims}), self.dv.head()
         )
         with pytest.raises(TypeError, match=r"either dict-like or a single int"):
-            self.dv.head([3])
+            self.dv.head([3])  # type: ignore[arg-type]
         with pytest.raises(TypeError, match=r"expected integer type"):
             self.dv.head(x=3.1)
         with pytest.raises(ValueError, match=r"expected positive int"):
@@ -1260,7 +1260,7 @@ def test_tail(self) -> None:
             self.dv.isel({dim: slice(-5, None) for dim in self.dv.dims}), self.dv.tail()
         )
         with pytest.raises(TypeError, match=r"either dict-like or a single int"):
-            self.dv.tail([3])
+            self.dv.tail([3])  # type: ignore[arg-type]
         with pytest.raises(TypeError, match=r"expected integer type"):
             self.dv.tail(x=3.1)
         with pytest.raises(ValueError, match=r"expected positive int"):
@@ -1273,7 +1273,7 @@ def test_thin(self) -> None:
             self.dv.thin(6),
         )
         with pytest.raises(TypeError, match=r"either dict-like or a single int"):
-            self.dv.thin([3])
+            self.dv.thin([3])  # type: ignore[arg-type]
         with pytest.raises(TypeError, match=r"expected integer type"):
             self.dv.thin(x=3.1)
         with pytest.raises(ValueError, match=r"expected positive int"):
@@ -2206,7 +2206,7 @@ def test_expand_dims_with_greater_dim_size(self) -> None:
         assert_identical(other_way_expected, other_way)
 
     def test_set_index(self) -> None:
-        indexes = [self.mindex.get_level_values(n) for n in self.mindex.names]
+        indexes = [self.mindex.get_level_values(n) for n in self.mindex.names]  # type: ignore[arg-type,unused-ignore]  # pandas-stubs varies
         coords = {idx.name: ("x", idx) for idx in indexes}
         array = DataArray(self.mda.values, coords=coords, dims="x")
         expected = self.mda.copy()
@@ -2237,7 +2237,7 @@ def test_set_index(self) -> None:
             obj.set_index(x="level_4")
 
     def test_reset_index(self) -> None:
-        indexes = [self.mindex.get_level_values(n) for n in self.mindex.names]
+        indexes = [self.mindex.get_level_values(n) for n in self.mindex.names]  # type: ignore[arg-type,unused-ignore]  # pandas-stubs varies
         coords = {idx.name: ("x", idx) for idx in indexes}
         expected = DataArray(self.mda.values, coords=coords, dims="x")
 
@@ -2335,10 +2335,18 @@ def test_array_interface(self) -> None:
         assert_equal(self.dv, np.maximum(self.dv, bar))
 
     def test_astype_attrs(self) -> None:
-        for v in [self.va.copy(), self.mda.copy(), self.ds.copy()]:
+        # Split into two loops for mypy - Variable, DataArray, and Dataset
+        # don't share a common base class, so mypy infers type object for v,
+        # which doesn't have the attrs or astype methods
+        for v in [self.mda.copy(), self.ds.copy()]:
             v.attrs["foo"] = "bar"
             assert v.attrs == v.astype(float).attrs
             assert not v.astype(float, keep_attrs=False).attrs
+        # Test Variable separately to avoid mypy inferring object type
+        va = self.va.copy()
+        va.attrs["foo"] = "bar"
+        assert va.attrs == va.astype(float).attrs
+        assert not va.astype(float, keep_attrs=False).attrs
 
     def test_astype_dtype(self) -> None:
         original = DataArray([-1, 1, 2, 3, 1000])