geotiff: reject tiled=False for VRT output and validate tile_size (#1862)

xrspatial/geotiff/__init__.py

@@ -1360,10 +1360,15 @@ def to_geotiff(data: xr.DataArray | np.ndarray,
             f"path must be a str or a binary file-like with a write() "
             f"method, got {type(path).__name__}")
 
+    _is_vrt_path = (
+        isinstance(path, str) and path.lower().endswith('.vrt'))
+
     # tile_size only applies to tiled output; warn if the caller passed a
     # non-default size alongside strip mode (it would otherwise be silently
-    # ignored).
-    if not tiled and tile_size != 256:
+    # ignored). The VRT path always tiles, so the warning would be
+    # misleading there -- the VRT branch below rejects tiled=False up front
+    # instead.
+    if not tiled and tile_size != 256 and not _is_vrt_path:
         warnings.warn(
             f"tile_size={tile_size} is ignored when tiled=False "
             "(strip layout). Pass tiled=True to use tile_size, or drop "
@@ -1373,7 +1378,18 @@ def to_geotiff(data: xr.DataArray | np.ndarray,
 
     # VRT tiled output (string paths only -- VRT writes a real .vrt file
     # plus per-tile GeoTIFFs to a directory)
-    if isinstance(path, str) and path.lower().endswith('.vrt'):
+    if _is_vrt_path:
+        if not tiled:
+            raise ValueError(
+                "tiled=False is not compatible with VRT output. "
+                "VRT writes a directory of tiled GeoTIFFs; pass "
+                "tiled=True or omit it.")
+        # The early ``if tiled: _validate_tile_size_arg(tile_size)`` check
+        # above already validates tile_size when tiled=True, but call it
+        # here as well so the VRT path stays self-contained against future
+        # changes to the early-validation gate (no-op on re-entry; either
+        # raises or returns).
+        _validate_tile_size_arg(tile_size)
         if cog:
             raise ValueError(
                 "cog=True is not compatible with VRT output. "

xrspatial/geotiff/tests/test_to_geotiff_vrt_tiled_validation_1862.py

@@ -0,0 +1,66 @@
+"""Regression tests for issue #1862.
+
+``to_geotiff(..., '.vrt', tiled=False, tile_size=0)`` previously warned that
+``tile_size`` was ignored, then crashed with ``ZeroDivisionError`` inside
+``_write_vrt_tiled`` because the VRT writer always tiles. The ``tiled=False``
+flag was never honored on the VRT path, and ``tile_size`` was only validated
+when ``tiled=True``, so an invalid ``tile_size=0`` slipped through.
+
+``to_geotiff`` now refuses ``tiled=False`` for ``.vrt`` paths up front with a
+``ValueError``, and validates ``tile_size`` unconditionally on the VRT
+branch so callers get a clear error before the writer divides by it.
+"""
+from __future__ import annotations
+
+import os
+
+import numpy as np
+import pytest
+import xarray as xr
+
+from xrspatial.geotiff import to_geotiff
+
+
+def _make_da(shape=(64, 64)):
+    arr = np.arange(np.prod(shape), dtype=np.float32).reshape(shape)
+    return xr.DataArray(arr, dims=['y', 'x'])
+
+
+def test_vrt_rejects_tiled_false_1862(tmp_path):
+    """``tiled=False`` is not a valid request for VRT output."""
+    da = _make_da()
+    out = os.path.join(str(tmp_path), 'vrt_tiled_false_1862.vrt')
+    with pytest.raises(ValueError, match='tiled=False is not compatible'):
+        to_geotiff(da, out, tiled=False)
+
+
+def test_vrt_tiled_false_zero_tile_size_raises_value_error_1862(tmp_path):
+    """``tiled=False`` plus ``tile_size=0`` must raise ``ValueError``,
+    not the previous ``ZeroDivisionError`` from inside the writer."""
+    da = _make_da()
+    out = os.path.join(
+        str(tmp_path), 'vrt_tiled_false_zero_1862.vrt')
+    with pytest.raises(ValueError) as exc:
+        to_geotiff(da, out, tiled=False, tile_size=0)
+    # Either the tiled=False guard or the tile_size validator may fire
+    # first; both produce ValueError, never ZeroDivisionError.
+    assert not isinstance(exc.value, ZeroDivisionError)
+
+
+def test_vrt_zero_tile_size_default_tiled_raises_value_error_1862(tmp_path):
+    """With the default ``tiled=True``, ``tile_size=0`` must surface from
+    the shared ``_validate_tile_size`` check, not a deep ``ZeroDivisionError``.
+    """
+    da = _make_da()
+    out = os.path.join(
+        str(tmp_path), 'vrt_default_tiled_zero_1862.vrt')
+    with pytest.raises(ValueError, match='tile_size'):
+        to_geotiff(da, out, tile_size=0)
+
+
+def test_vrt_default_args_still_succeeds_1862(tmp_path):
+    """Sanity: the default-args VRT write path is unaffected by the fix."""
+    da = _make_da()
+    out = os.path.join(str(tmp_path), 'vrt_default_1862.vrt')
+    to_geotiff(da, out)
+    assert os.path.exists(out)