PYTHON-5782 Coverage increase, remove old code in `message.py` by aclark4life · Pull Request #2772 · mongodb/mongo-python-driver

aclark4life · 2026-04-23T21:42:44Z

Changes in this PR

Adds test/test_message.py with unit tests for pymongo/message.py.

Also removes a dead code branch in _convert_write_result() — a legacy compatibility shim for MongoDB < 2.6 that manually reconstructed the upserted _id when it wasn't an ObjectId. MongoDB 2.6+ always returns the upserted field directly, so this branch was unreachable.

Also fixes a bug in _raise_document_too_large() where the error message used {operation!r} (repr formatting), producing 'update' command document too large instead of update command document too large. This mismatched the C extension's %s-formatted equivalent and broke the new test.

Tests cover:

Result / error conversion

_convert_exception() — converts an Exception into an errmsg/errtype failure document for event publishing
_convert_client_bulk_exception() — same as above but also captures the error code, used by the client-level bulk write API
_convert_write_result() — converts a legacy GLE (Get Last Error) write result into write-command format, handling insert/update/delete/upsert, wtimeout, and errInfo branches
_raise_document_too_large() — raises DocumentTooLarge with a size-aware message for inserts or a generic message for other operations

Wire-format message construction

_op_msg() — builds an OP_MSG wire message, injecting $db and $readPreference, and temporarily popping document-sequence fields before encoding

Command builders

_gen_find_command() — builds a find command document from a query spec, applying projections, skip/limit, batch size, read concern, collation, and cursor options
_gen_get_more_command() — builds a getMore command document, conditionally including batch size, maxTimeMS, and comment (gated on wire version ≥ 9)

Read preference

_maybe_add_read_preference() — injects $readPreference into a query spec for non-primary modes, skipping plain secondaryPreferred when no tags or maxStalenessSeconds are set

Test Plan

Added unit tests using a real ZlibContext for compression paths and a MagicMock connection for _gen_get_more_command. Focuses on the pure-Python code paths without requiring a live MongoDB server.

hatch run test:test test/test_message.py -v

Checklist

Checklist for Author

Did you update the changelog (if necessary)?
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Is any followup work tracked in a JIRA ticket? If so, add link(s).

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Does the title of the PR reference a JIRA Ticket?
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Is all relevant documentation (README or docstring) updated?

Copilot

Pull request overview

This PR adds a new unit test module to increase coverage of pymongo/message.py by exercising message-building utilities and related pure-Python helper functions without requiring a live MongoDB server.

Changes:

Adds test/test_message.py with unit tests for message helpers (read preference wrapping, command generation, write-result conversion).
Adds tests covering OP_MSG / OP_QUERY / OP_GET_MORE message construction in both compressed and uncompressed paths.
Adds tests for error conversion and document-too-large error formatting.

codecov-commenter · 2026-04-23T22:32:21Z

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

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- Replace _MockCtx with real ZlibContext(-1) to satisfy the SnappyContext | ZlibContext | ZstdContext union type - Annotate docs list as list to satisfy the Mapping invariance check - Add # type: ignore[arg-type] on _MockConn call sites for _gen_get_more_command (mocking AsyncConnection | Connection fully would require a much heavier stub)

Address Copilot feedback: add tests for legacy upsert _id fallback in _convert_write_result and for the zlib-compressed _op_msg path.

Guard zlib compression test with _have_zlib() skip condition.

- Use keyword args in all _gen_find_command and _gen_get_more_command calls - Fix test_op_msg_max_doc_size_matches_largest_encoded_doc to use docs of different sizes so the max() assertion is meaningful - Use assertRaisesRegex with the exact message in test_raise_document_too_large_update_generic_message - Remove !r from the DocumentTooLarge message in _raise_document_too_large so it matches

…pr quotes

NoahStapp · 2026-06-16T14:07:20Z

Typecheck is failing.

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Copilot AI review requested due to automatic review settings April 23, 2026 21:42

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aclark4life force-pushed the PYTHON-5782 branch from 45f0c94 to bde1957 Compare May 6, 2026 01:26

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aclark4life force-pushed the PYTHON-5782 branch from 9322c98 to c2cf60d Compare May 6, 2026 18:21

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aclark4life force-pushed the PYTHON-5782 branch 2 times, most recently from a6c8f8e to a8d9f92 Compare May 6, 2026 20:34

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aclark4life changed the title ~~PYTHON-5782 Increase code coverage for message.py~~ PYTHON-5782 Improve code coverage for message.py May 7, 2026

aclark4life changed the title ~~PYTHON-5782 Improve code coverage for message.py~~ PYTHON-5782 Improve coverage for message.py May 7, 2026

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aclark4life changed the title ~~PYTHON-5782 Improve coverage for message.py~~ PYTHON-5782 Improve coverage for message.py May 7, 2026

aclark4life changed the title ~~PYTHON-5782 Improve coverage for message.py~~ PYTHON-5782 Coverage improvements for message.py May 7, 2026

aclark4life changed the title ~~PYTHON-5782 Coverage improvements for message.py~~ PYTHON-5782 Coverage improvement for message.py May 7, 2026

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Comment thread pymongo/message.py

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aclark4life force-pushed the PYTHON-5782 branch from ce1b47c to 408639c Compare June 15, 2026 17:05

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aclark4life added 12 commits June 15, 2026 16:10

PYTHON-5782 Increase code coverage for message.py from 76.87% to >=80%

eaf11dc

Noah feedback

bde76a7

Jib review

465d774

Copilot review

ceab4e4

Claude review

1a13a1c

Consolidate 7 classes into one

62db815

Copilot review

cc223fe

Address Copilot feedback: add tests for legacy upsert _id fallback in _convert_write_result and for the zlib-compressed _op_msg path.

Copilot review

6132ea8

Guard zlib compression test with _have_zlib() skip condition.

Noah feedback

e7051cf

Copilot feedback

dc1094d

aclark4life force-pushed the PYTHON-5782 branch from 75a9e28 to dc1094d Compare June 15, 2026 20:10

PYTHON-5782 Fix document-too-large error message dropping spurious re…

03fb33e

…pr quotes

PYTHON-5782 Fix mypy error in test_message.py

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NoahStapp approved these changes Jun 16, 2026

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aclark4life merged commit eb42bc3 into mongodb:master Jun 16, 2026
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aclark4life deleted the PYTHON-5782 branch June 16, 2026 15:43

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aclark4life commented Apr 23, 2026 •

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