BUG: Raise overflow error when nodata conversion is unsafe

docs/history.rst

@@ -3,6 +3,7 @@ History
 
 Latest
 ------
+- BUG: Raise OverflowError when nodata data type conversion is unsafe (pull #782)
 
 0.15.5
 ------

rioxarray/raster_writer.py

@@ -8,8 +8,6 @@
 - https://github.com/dymaxionlabs/dask-rasterio/blob/8dd7fdece7ad094a41908c0ae6b4fe6ca49cf5e1/dask_rasterio/write.py  # noqa: E501
 
 """
-import warnings
-
 import numpy
 import rasterio
 from rasterio.windows import Window
@@ -121,17 +119,21 @@ def _ensure_nodata_dtype(original_nodata, new_dtype):
     if the value of the nodata value changed.
     """
     # Complex-valued rasters can have real-valued nodata
-    if str(new_dtype).startswith("c"):
+    new_dtype = numpy.dtype(new_dtype)
+    if numpy.issubdtype(new_dtype, numpy.complexfloating):
         nodata = original_nodata
     else:
         original_nodata = float(original_nodata)
-        nodata = numpy.dtype(new_dtype).type(original_nodata)
+        failure_message = (
+            f"Unable to convert nodata value ({original_nodata}) to "
+            f"new dtype ({new_dtype})."
+        )
+        try:
+            nodata = new_dtype.type(original_nodata)
+        except OverflowError as error:
+            raise OverflowError(failure_message) from error
         if not numpy.isnan(nodata) and original_nodata != nodata:
-            warnings.warn(
-                f"The nodata value ({original_nodata}) has been automatically "
-                f"changed to ({nodata}) to match the dtype of the data."
-            )
-
+            raise OverflowError(failure_message)
     return nodata
 
 

test/integration/test_integration_rioxarray.py

@@ -1886,19 +1886,9 @@ def test_to_raster__different_dtype(tmp_path, windowed):
     )
     test_nd.rio.write_crs("EPSG:4326", inplace=True)
     tmpfile = tmp_path / "dtype.tif"
-    with pytest.warns(
-        UserWarning,
-        match=(
-            r"The nodata value \(-1.1\) has been automatically changed to "
-            r"\(255\) to match the dtype of the data."
-        ),
-    ):
+
+    with pytest.raises(OverflowError, match="Unable to convert nodata value"):
         test_nd.rio.to_raster(tmpfile, dtype=numpy.uint8, windowed=windowed)
-    with rioxarray.open_rasterio(tmpfile) as xds:
-        assert str(xds.dtype) == "uint8"
-        assert xds.attrs["_FillValue"] == 255
-        assert xds.rio.nodata == 255
-        assert xds.squeeze().values[1, 1] == 255
 
 
 def test_missing_spatial_dimensions():
@@ -2384,17 +2374,8 @@ def test_write_nodata__different_dtype(nodata):
         dims=("y", "x"),
         coords={"y": numpy.arange(1, 6), "x": numpy.arange(2, 7)},
     )
-    with pytest.warns(
-        UserWarning,
-        match=(
-            r"The nodata value \(-1.1\) has been automatically changed to "
-            r"\(-1\) to match the dtype of the data."
-        ),
-    ):
-        test_nd = test_da.rio.write_nodata(nodata)
-    assert not test_da.attrs
-    assert test_nd.attrs["_FillValue"] == -1
-    assert test_nd.rio.nodata == -1
+    with pytest.raises(OverflowError, match="Unable to convert nodata value"):
+        test_da.rio.write_nodata(nodata)
 
 
 @pytest.mark.parametrize("nodata", [-1.1, "-1.1"])
@@ -2406,14 +2387,8 @@ def test_nodata_reader__different_dtype(nodata):
         attrs={"_FillValue": nodata},
     )
     assert test_da.attrs["_FillValue"] == nodata
-    with pytest.warns(
-        UserWarning,
-        match=(
-            r"The nodata value \(-1.1\) has been automatically changed to "
-            r"\(255\) to match the dtype of the data."
-        ),
-    ):
-        assert test_da.rio.nodata == 255
+    with pytest.raises(OverflowError, match="Unable to convert nodata value"):
+        test_da.rio.nodata
 
 
 def test_isel_window():