Improve unit-test coverage across crates

[YuanyuanTian-hh]

Summary

Adds targeted unit tests across several crates to raise workspace test coverage, prunes a few low-value tests, and adds one Codecov ignore so the headline coverage reflects unit-testable code.

Changes

• Unit tests added/expanded in:
  • diskann-bftree (error display/acknowledge/escalate paths, neighbor + vector error paths, getters)
  • diskann-label-filter (attribute store CRUD, poisoned-lock recovery, identity hasher, query evaluator default methods, parser, posting lists, document provider status logic)
  • diskann-providers (PQ construction/storage, timer)
  • diskann-quantization (multi-vector distance factory)
  • diskann-tools (ground-truth + search-index utils, bin tools)
  • �ectorset (loader file-IO)
• Dev-dependencies: added empfile (dev-only) to diskann-tools and �ectorset for file-IO tests; Cargo.lock updated accordingly.
• Codecov: ignore �ectorset/src/main.rs (binary entry point / Redis CLI, not unit-testable).

Validation

• cargo test passes for all touched crates (0 failures).
• cargo clippy --lib --tests clean for the edited crates.

Notes

• No production/runtime dependencies changed (only [dev-dependencies]).

[Copilot]

Pull request overview

This PR increases unit-test coverage across multiple workspace crates by adding targeted tests for error paths, parsing, storage helpers, and binary utilities, and adjusts coverage reporting to better reflect unit-testable code.

Changes:

• Added/expanded unit tests across diskann-bftree, diskann-label-filter, diskann-providers, diskann-quantization, diskann-tools, and vectorset.
• Added tempfile as a workspace dev-dependency where needed for file-IO tests; updated Cargo.lock.
• Updated Codecov configuration to ignore vectorset/src/main.rs (binary entry point).

Reviewed changes

Copilot reviewed 34 out of 35 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vectorset/src/loader.rs	Adds async unit tests covering dataset loading/iteration and malformed input handling.
vectorset/Cargo.toml	Adds tempfile as a dev-dependency for new loader tests.
diskann-tools/src/utils/search_index_utils.rs	Adds tests for truthset/range-truthset loading helpers.
diskann-tools/src/utils/ground_truth.rs	Adds tests for ground-truth generation (including vector filters, inserts, labels, multivec).
diskann-tools/src/bin/subsample_bin.rs	Adds tests for RNG seeding and sampling probability edge cases.
diskann-tools/src/bin/generate_minmax.rs	Adds tests for dispatch validation and output header writing.
diskann-tools/Cargo.toml	Adds tempfile dev-dependency for new tests.
diskann-quantization/src/multi_vector/distance/factory.rs	Adds tests exercising all ISA selection/build paths and unsupported-ISA errors.
diskann-providers/src/utils/timer.rs	Adds coverage for elapsed time / gcycles helpers.
diskann-providers/src/storage/pq_storage.rs	Adds tests for getters and error paths (missing file, dimension mismatch).
diskann-providers/src/model/pq/pq_construction.rs	Adds tests for PQ construction error paths from membufs.
diskann-providers/src/model/pq/fixed_chunk_pq_table.rs	Adds tests for direct distance methods and compress/inflate behaviors.
diskann-label-filter/src/utils/jsonl_reader.rs	Adds tests for IO/parse/display error paths and query parsing failures.
diskann-label-filter/src/utils/flatten_utils.rs	Adds tests for remaining wrapper helper functions.
diskann-label-filter/src/traits/query_evaluator.rs	Adds tests validating default trait methods (is_match, count_matches).
diskann-label-filter/src/stores/bftree_store.rs	Adds tests for error conversions and Display.
diskann-label-filter/src/set/roaring_set_provider.rs	Adds tests for CRUD helpers and IdentityHasher specializations.
diskann-label-filter/src/parser/query_parser.rs	Adds tests for additional operators, invalid types, and Display coverage.
diskann-label-filter/src/parser/ast.rs	Adds tests for Display coverage and formatting edge cases.
diskann-label-filter/src/kv_index/query_evaluator_impl.rs	Adds tests for corrupt posting-list data errors during range evaluation.
diskann-label-filter/src/kv_index/posting_list_accessor_impl.rs	Adds tests for posting-list accessor read/missing/corrupt behaviors.
diskann-label-filter/src/kv_index/inverted_index_provider_impl.rs	Adds tests for insert/delete/update and batch operations over posting lists.
diskann-label-filter/src/kv_index/generic_index.rs	Adds tests for field normalization and posting-list load/corruption paths.
diskann-label-filter/src/inline_beta_search/predicate_evaluator.rs	Adds tests for boolean predicate evaluation semantics.
diskann-label-filter/src/inline_beta_search/inline_beta_filter.rs	Adds tests validating beta scaling depending on predicate match.
diskann-label-filter/src/inline_beta_search/encoded_document_accessor.rs	Adds tests for distance scaling and missing-label error handling.
diskann-label-filter/src/encoded_attribute_provider/roaring_attribute_store.rs	Adds tests for attribute-store CRUD and error conditions.
diskann-label-filter/src/encoded_attribute_provider/encoded_attribute_accessor.rs	Adds tests for visiting labels, multi-id iteration, and poisoned-lock recovery.
diskann-label-filter/src/encoded_attribute_provider/document_provider.rs	Adds tests for status logic and delegated behaviors.
diskann-bftree/src/vectors.rs	Adds tests for buffer-dimension errors and deleted/not-found paths.
diskann-bftree/src/quant.rs	Adds tests for quantized get_vector_into error paths.
diskann-bftree/src/neighbors.rs	Adds tests for neighbor-provider validation/error paths.
diskann-bftree/src/lib.rs	Adds tests for error Display/acknowledge/escalate behaviors.
Cargo.lock	Records added tempfile dev-dependency usage.
.codecov.yml	Ignores vectorset/src/main.rs to avoid penalizing non-unit-testable binary entry code.

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[harsha-simhadri]

@YuanyuanTian-hh thanks for this change. A few requests:

• diskann-provider will soon be gone, so lets not add more stuff to it.
• The final form of diskann-label-filter is still unclear. So lets hold off adding more tests there.
• Break the rest into seperate PRs for changes to each crate so the relevant people can sign off.