test: add 50 unit tests for loading and processing data

[bianjh-cloud]

Changes

Functions Tested

• add_VDJ_metadata() - VDJ metadata integration
• convert_human_gene_list() - Human to mouse gene list conversion
• run_batch_correction() - Batch correction workflows
• run_AUCell() - AUCell scoring
• filter_doublets() - Doublet filtering

Changes

• Added 5 new test files covering unit tests for each function
• Added test fixture: BRCA downsampled Seurat object
• Added helper functions for test data setup and selection
• Included celldex reference cache for reproducible tests

Test Data

Tests use the downsampled BRCA dataset (BRCA_Combine_and_Renormalize_SO_downsample.rds) and helper functions for loading plain and processed PBMC data.

Issues

#50

PR Checklist

(Strikethrough any points that are not applicable.)

• This comment contains a description of changes with justifications, with any relevant issues linked.
• Write unit tests for any new features, bug fixes, or other code changes.
• Update the docs if there are any API changes (roxygen2 comments, vignettes, readme, etc.).
• Update NEWS.md with a short description of any user-facing changes and reference the PR number. Follow the style described in https://style.tidyverse.org/news.html
• Run devtools::check() locally and fix all notes, warnings, and errors.
• R-CMD-check succeeds on the most recent user commit.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46.02%. Comparing base (3d43595) to head (ea1da66).

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #53       +/-   ##
===========================================
+ Coverage   17.56%   46.02%   +28.45%     
===========================================
  Files          21       21               
  Lines         814      830       +16     
===========================================
+ Hits          143      382      +239     
+ Misses        671      448      -223     

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[bianjh-cloud]

Error: Error: R CMD check found WARNINGs
Execution halted
'::' or ':::' import not declared from: ‘stringr’

Fixed: updated DESCRIPTIONS to include stringr