lint.

python-package/xgboost/testing/data_iter.py

@@ -4,9 +4,10 @@
 
 import numpy as np
 
-import xgboost
 from xgboost import testing as tm
 
+from ..core import DataIter, ExtMemQuantileDMatrix, QuantileDMatrix
+
 
 def run_mixed_sparsity(device: str) -> None:
     """Check QDM with mixed batches."""
@@ -25,22 +26,22 @@ def run_mixed_sparsity(device: str) -> None:
         X = [cp.array(batch) for batch in X]
 
     it = tm.IteratorForTest(X, y, None, cache=None, on_host=False)
-    Xy_0 = xgboost.QuantileDMatrix(it)
+    Xy_0 = QuantileDMatrix(it)
 
     X_1, y_1 = tm.make_sparse_regression(256, 16, 0.1, True)
     X = [X_0, X_1, X_2]
     y = [y_0, y_1, y_2]
     X_arr = np.concatenate(X, axis=0)
     y_arr = np.concatenate(y, axis=0)
-    Xy_1 = xgboost.QuantileDMatrix(X_arr, y_arr)
+    Xy_1 = QuantileDMatrix(X_arr, y_arr)
 
     assert tm.predictor_equal(Xy_0, Xy_1)
 
 
 def check_invalid_cat_batches(device: str) -> None:
     """Check error message for inconsistent feature types."""
 
-    class _InvalidCatIter(xgboost.DataIter):
+    class _InvalidCatIter(DataIter):
         def __init__(self) -> None:
             super().__init__(cache_prefix=None)
             self._it = 0
@@ -57,8 +58,8 @@ def next(self, input_data: Callable) -> bool:
                 cat_ratio=1.0 if self._it == 0 else 0.5,
             )
             if device == "cuda":
-                import cudf
-                import cupy
+                import cudf  # pylint: disable=import-error
+                import cupy  # pylint: disable=import-error
 
                 X = cudf.DataFrame(X)
                 y = cupy.array(y)
@@ -74,10 +75,10 @@ def reset(self) -> None:
     import pytest
 
     with pytest.raises(ValueError, match="Inconsistent feature types between batches"):
-        xgboost.ExtMemQuantileDMatrix(it, enable_categorical=True)
+        ExtMemQuantileDMatrix(it, enable_categorical=True)
 
 
-class CatIter(xgboost.DataIter):  # pylint: disable=too-many-instance-attributes
+class CatIter(DataIter):  # pylint: disable=too-many-instance-attributes
     """An iterator for testing categorical features."""
 
     def __init__(  # pylint: disable=too-many-arguments,too-many-locals