[Cosmos] [Embedding V0] Unit tests for embedding generation

[ananth7592]

Unit tests for embedding generation

Parent: 46729
Depends on: 46730, 46731, 46732, 46733, 46734

Goal

Exercise the new code paths end-to-end with mocks (no emulator). Lives under sdk/cosmos/azure-cosmos/tests/.

Scope

1. _PartitionedQueryExecutionInfo parser:

   • Returns embeddingParameterMap from leaf queryInfo.
   • Returns embeddingParameterMap from hybridSearchQueryInfo.
   • Returns {} when neither is present.

2. _QueryFeature.EmbeddingGeneration advertised string:

   • Sync _GetQueryPlanThroughGateway: token present iff options["embeddingGenerator"] is not None.
   • Async _GetQueryPlanThroughGateway: same.

3. _resolve_embeddings (sync + async):

   • Map empty → no-op, parameters list unchanged identity.
   • Map non-empty + no generator → ValueError mentioning embedding_generator.
   • Generator returns wrong cardinality → ValueError with both counts.
   • Generator returns null at index N → ValueError mentioning index N.
   • Generator returns valid vectors → params extended with {"name": key, "value": [...]} in stable order regardless of map insertion order.
   • Original self._parameters list identity unchanged (test that the helper does not mutate the caller's list).
   • Async aggregator with sync generator → TypeError early.

4. Diagnostics (mock the OTel tracer):

   • Span named cosmos.embedding_generation is recorded.
   • Attributes: count, generator_type, latency_ms.
   • On generator exception → span records the error.
   • When no tracer is configured → no-op (no exceptions, no extra calls).

5. Pipeline / dispatch:

   • Mock plan triggers hybrid-search aggregator with mocked generator → component queries' parameters include the embedding entries.
   • Mock plan triggers fast-fail when embeddingGenerator is absent.

Files touched

• sdk/cosmos/azure-cosmos/tests/test_query_execution_info.py (new or extended)
• sdk/cosmos/azure-cosmos/tests/test_embedding_generation.py (new — sync)
• sdk/cosmos/azure-cosmos/tests/test_embedding_generation_async.py (new — async)
• sdk/cosmos/azure-cosmos/tests/test_query_plan_features.py (or wherever the supported-features header is asserted today)

Acceptance

• All new tests pass on pytest.
• Coverage of _resolve_embeddings (sync + async) at 100 %.
• No emulator dependency in any of these tests.