Add $tsIncrement compatibility tests

[RyanGarfinkel]

What does this PR do?

This PR introduces additional compatibility tests for the $tsIncrement operator. This includes null/missing values, invalid types, boundary values, and nested field access. Wiring tests were also added to verify functionality in $match, $expr, and $group expressions. An additional error code, TS_INCREMENT_TYPE_ERROR was added specifically for MongoDB type mismatches.

Why was this PR needed?

This PR Closes #210, which required adding additional test coverage to the $tsIncrement operator. Initially, this operator only had one smoke test, which tested basic functionality, not including null/missing input and invalid types.

What are the relevant issue numbers?

Closes #210

Does this PR meet the acceptance criteria?

• Tests added for new/changed behavior
• All tests passing
• Follows project style guide
• No breaking changes introduced (new tests added)
• Documentation updated (if applicable)

[documentdb-triage-tool]

🤖 Auto-triaged by documentdb-triage-tool.

Applied: compatibility test, enhancement
Project fields suggested: Component test-coverage · Priority P2 · Effort M · Status Needs Review
Confidence: 0.30 (deterministic)

Reasoning

component from path globs (test-coverage, test-framework); effort from diff stats (267+0 LOC, 4 files); LLM failed: Invalid response body while trying to fetch https://api.anthropic.com/v1/messages: Premature close

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[Copilot]

Pull request overview

This PR expands the compatibility test coverage for the $tsIncrement aggregation expression operator, ensuring it behaves correctly across null/missing inputs, boundary values, invalid types, nested field paths, and usage inside common pipeline contexts like $match/$expr and $group.

Changes:

• Added a dedicated TS_INCREMENT_TYPE_ERROR error code constant for $tsIncrement type-mismatch failures.
• Introduced comprehensive $tsIncrement expression tests (null/missing, boundaries, invalid BSON types, nested field access).
• Added “wiring” tests to validate $tsIncrement works inside $match with $expr and inside $group expressions.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
documentdb_tests/framework/error_codes.py	Adds a new server error code constant for $tsIncrement type mismatches.
documentdb_tests/compatibility/tests/core/operator/stages/match/test_match_with_expr.py	Adds a $tsIncrement usage test inside $match + $expr.
documentdb_tests/compatibility/tests/core/operator/stages/group/test_group_expr_operators.py	Adds $group coverage for $tsIncrement in _id and accumulator expressions.
documentdb_tests/compatibility/tests/core/operator/expressions/timestamp/tsIncrement/test_tsIncrement.py	Adds broad operator-focused test coverage for $tsIncrement behavior and error handling.