Add $stddevsamp compatibility tests

[Jhr-4]

Add compatibility test coverage for $stdDevSamp expression operator covering core, boundary, type validation, null/missing cases.

[Copilot]

Pull request overview

Adds a comprehensive compatibility test suite for the $stdDevSamp expression accumulator under core/operator/expressions/accumulator/stdDevSamp/, covering core math behavior, boundary/precision behaviors, null/missing semantics, non-numeric handling, and special floating-point values.

Changes:

• Introduces core correctness tests across numeric BSON types and representative numeric patterns (mixed types, negative values, large N, zero variance).
• Adds targeted suites for boundary/precision-loss scenarios and for NaN/Infinity propagation behavior.
• Adds input-form coverage (literal traversal, expression operands, field-path traversal, and invalid field-path parsing) plus null/missing and non-numeric ignore rules.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
documentdb_tests/compatibility/tests/core/operator/expressions/accumulator/stdDevSamp/test_expression_stdDevSamp_core.py	Core numeric correctness and baseline rules (N<2 → null, zero variance, mixed types).
documentdb_tests/compatibility/tests/core/operator/expressions/accumulator/stdDevSamp/test_expression_stdDevSamp_boundaries.py	Boundary and precision-loss/overflow behaviors for ints/doubles.
documentdb_tests/compatibility/tests/core/operator/expressions/accumulator/stdDevSamp/test_expression_stdDevSamp_special_values.py	NaN/Infinity behavior coverage for float + Decimal128.
documentdb_tests/compatibility/tests/core/operator/expressions/accumulator/stdDevSamp/test_expression_stdDevSamp_null_missing.py	Null/missing handling coverage (scalar + array shapes).
documentdb_tests/compatibility/tests/core/operator/expressions/accumulator/stdDevSamp/test_expression_stdDevSamp_non_numeric.py	Behavior when inputs include non-numeric BSON types (ignored vs scalar).
documentdb_tests/compatibility/tests/core/operator/expressions/accumulator/stdDevSamp/test_expression_stdDevSamp_input_forms.py	Expression input forms (literal traversal, operands, document paths) + invalid field path errors.

[documentdb-triage-tool]

🤖 Auto-triaged by documentdb-triage-tool.

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

Reasoning

component from path globs (test-coverage); effort from diff stats (859+0 LOC, 6 files); LLM failed: Invalid response body while trying to fetch https://api.anthropic.com/v1/messages: Premature close

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