Use VirtualStorageProvider::new_overlay(test_data_root()) in tests

[Copilot]

Test files were using hardcoded workspace root paths (env!("CARGO_MANIFEST_DIR").parent().unwrap()) instead of the centralized test_data_root() helper from diskann-utils.

Changes

• Standardized test data resolution: Replaced all hardcoded workspace_root patterns with test_data_root() across 17 test functions in 7 files
• Fixed path prefixes: Removed /test_data/ prefix from test file paths since test_data_root() already resolves to the test_data directory
• Updated dependencies: Added testing feature for diskann-utils in dev-dependencies

Before

let workspace_root = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"))
    .parent()
    .unwrap()
    .to_path_buf();
let storage_provider = VirtualStorageProvider::new_overlay(workspace_root);
let file = "/test_data/sift/siftsmall_learn.bin";

After

let storage_provider = VirtualStorageProvider::new_overlay(test_data_root());
let file = "/sift/siftsmall_learn.bin";

Files affected:

• diskann-providers/src/index/diskann_async.rs
• diskann-providers/src/storage/{pq_storage.rs, index_storage.rs}
• diskann-providers/src/utils/{normalizing_util.rs, kmeans.rs}
• diskann-providers/src/model/pq/{fixed_chunk_pq_table.rs, pq_construction.rs}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Use VirtualStorageProvider::new_overlay(test_data()) in tests</issue_title>
<issue_description>Update the unit tests so that any hardcoded test_data in string paths and workspace_root usages are replaced with VirtualStorageProvider::new_overlay(test_data_root()).

Here is an example of expected pattern:

        let storage_provider = VirtualStorageProvider::new_overlay(test_data_root());
        let dataset_file = "/sift/siftsmall_learn.bin";
        let mut file = storage_provider.open_reader(dataset_file).unwrap();

Ensure that all unit tests still pass.

Original comment:

Something we should also do (maybe in another PR) is to replace all uses of test_data with the file system resolution in diskann-utils. I think a few fell through the cracks when test data was consolidated.

Originally posted by @hildebrandmw in #700</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Use VirtualStorageProvider::new_overlay(test_data()) in tests #704

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[Copilot]

Pull request overview

This PR standardizes test data resolution across the diskann-providers crate by replacing hardcoded workspace root path patterns with the centralized test_data_root() helper function from diskann-utils. The changes are part of a broader effort (following PR #700) to ensure tests use the virtual filesystem overlay pattern consistently and avoid direct filesystem writes during testing.

Changes:

• Replaced std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR")).parent().unwrap() patterns with test_data_root() across 17 test functions
• Updated test file path constants and variables to remove the /test_data/ prefix (since test_data_root() already points to the test_data directory)
• Added diskann-utils with "testing" feature to dev-dependencies to access the test_data_root() function

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
diskann-providers/src/utils/normalizing_util.rs	Updated 1 test function to use test_data_root() and removed /test_data/ prefix from paths
diskann-providers/src/utils/kmeans.rs	Updated 1 test function to use test_data_root(), removed unused PathBuf import, and fixed path prefix
diskann-providers/src/storage/pq_storage.rs	Updated 4 test functions and 3 const path declarations to use test_data_root() with corrected path prefixes
diskann-providers/src/storage/index_storage.rs	Updated 1 test function to use test_data_root() and corrected file path
diskann-providers/src/model/pq/pq_construction.rs	Updated 4 test functions and const path declarations to use test_data_root() with corrected prefixes
diskann-providers/src/model/pq/fixed_chunk_pq_table.rs	Updated 3 test functions to use test_data_root() and removed /test_data/ prefix from paths
diskann-providers/src/index/diskann_async.rs	Updated 3 test functions and 1 const path declaration to use test_data_root() with corrected paths
diskann-providers/Cargo.toml	Added diskann-utils with "testing" feature to dev-dependencies

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.00%. Comparing base (f3fcaae) to head (ddd0e45).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #726      +/-   ##
==========================================
- Coverage   89.01%   89.00%   -0.01%     
==========================================
  Files         428      428              
  Lines       78294    78234      -60     
==========================================
- Hits        69692    69632      -60     
  Misses       8602     8602              

Files with missing lines	Coverage Δ
diskann-providers/src/index/diskann_async.rs	96.35% <100.00%> (-0.02%)	⬇️
...ann-providers/src/model/pq/fixed_chunk_pq_table.rs	95.15% <100.00%> (-0.07%)	⬇️
diskann-providers/src/model/pq/pq_construction.rs	92.53% <100.00%> (-0.07%)	⬇️
diskann-providers/src/storage/index_storage.rs	99.71% <100.00%> (-0.01%)	⬇️
diskann-providers/src/storage/pq_storage.rs	88.23% <100.00%> (-0.47%)	⬇️
diskann-providers/src/utils/kmeans.rs	96.16% <100.00%> (-0.03%)	⬇️
diskann-providers/src/utils/normalizing_util.rs	72.17% <100.00%> (-0.94%)	⬇️

... and 2 files with indirect coverage changes

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