SNOW-2408964: support custom_schema when reading xml

[sfc-gh-yuwang]

1. Which Jira issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Fixes SNOW-2408964

2. Fill out the following pre-review checklist:

   • I am adding a new automated test(s) to verify correctness of my new code
     • If this test skips Local Testing mode, I'm requesting review from @snowflakedb/local-testing
   • I am adding new logging messages
   • I am adding a new telemetry message
   • I am adding new credentials
   • I am adding a new dependency
   • If this is a new feature/behavior, I'm adding the Local Testing parity changes.
   • I acknowledge that I have ensured my changes to be thread-safe. Follow the link for more information: Thread-safe Developer Guidelines
   • If adding any arguments to public Snowpark APIs or creating new public Snowpark APIs, I acknowledge that I have ensured my changes include AST support. Follow the link for more information: AST Support Guidelines

3. Please describe how your code solves the related issue.

   Here is a doc to talk about the behavior of XML read with user schema in snowpark:
   https://docs.google.com/document/d/1W3os2SGbO_M89TjIa7xVuNrQ0RDDuGMHEOBHFuw0OYw/edit?tab=t.0

[sfc-gh-aalam]

Suggested change

	raise ValueError("When read XML with user schema, rowtag must be set.")
	raise ValueError("When reading XML with user schema, rowtag must be set.")

[sfc-gh-aalam]

does this really need to be a function?

[sfc-gh-yuwang]

you are right, I removed this function

[sfc-gh-aalam]

why are we using single_quote here?

[sfc-gh-yuwang]

currently all column name is produced with a single quote around,
I am not sure why we are having this behavior but I think we should not change now as it would be a BCR
single quote is added here so that we can correctly read the column

[sfc-gh-aalam]

Ahh, I think I remember Jianzhun mentioning we use PIVOT and it snowflake pivot adds single quote for string, and datetime columns. This could break since server side is planning to do a BCR to remove quotes.

[graphite-app]

Test regex pattern mismatch with actual error message. The test expects "When read XML with user schema, rowtag must be set." but the actual error message in dataframe_reader.py:1392 is "When reading XML with user schema, rowtag must be set." (note "reading" vs "read"). This test will fail.

# Fix: Update the match pattern to match the actual error message
with pytest.raises(
    ValueError, match="When reading XML with user schema, rowtag must be set."
):

Suggested change

	with pytest.raises(
	ValueError, match="When read XML with user schema, rowtag must be set."
	):
	session.read.schema(user_schema).xml(f"@{tmp_stage_name}/{test_file_books_xml}")
	with pytest.raises(
	ValueError, match="When reading XML with user schema, rowtag must be set."
	):
	session.read.schema(user_schema).xml(f"@{tmp_stage_name}/{test_file_books_xml}")

Spotted by Graphite Agent



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[sfc-gh-aling]

can we have one simple case for nested data? books2.xml seems to be a nested one

[sfc-gh-aling]

LGTM.
can you also help address the test coverage before merging it?