Fix: Ensure DataStub size is updated when the underlying dataset is expanded via a DataPipe

[ehennestad]

Motivation

Fix wrong assumption in PR:

• Refactor DataStub for better cloud performance #755

That PR changed DataStub to resolve data type and size once, and keep values cached. However a dataset represented by a DataStub can change size if expanded via the DataPipe/BoundPipe class. This PR ensures the size of a DataStub is updated whenever a dataset is expanded via a DataPipe object.

This PR also includes a refactor of DataStub, adding a maxSize property and improving the way a BoundPipe resolves its current_size and max_size.

How to test the behavior?

Show here how to reproduce the new behavior (can be a bug fix or a new feature)

Checklist

• Have you ensured the PR description clearly describes the problem and solutions?
• Have you checked to ensure that there aren't other open or previously closed Pull Requests for the same change?
• If this PR fixes an issue, is the first line of the PR description fix #XX where XX is the issue number?

[codecov]

Codecov Report

❌ Patch coverage is 96.29630% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.60%. Comparing base (42fe0f1) to head (4173d3b).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
+types/+untyped/@DataStub/DataStub.m	94.44%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #766   +/-   ##
=======================================
  Coverage   95.59%   95.60%           
=======================================
  Files         182      183    +1     
  Lines        6380     6388    +8     
=======================================
+ Hits         6099     6107    +8     
  Misses        281      281           

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[Copilot]

Pull Request Overview

This PR refactors the DataStub class to add a maxDims property and introduces a new utility function io.space.getSize for retrieving dataset dimensions. The changes improve code organization by centralizing dimension retrieval logic and enabling BoundPipe to access maximum dimensions through DataStub.

• Introduced maxDims dependent property to track maximum dataset dimensions
• Created io.space.getSize utility function to consolidate dimension retrieval logic
• Updated subsref to support multiple output arguments for proper nargout behavior
• Added numArgumentsFromSubscript method to handle compound data type indexing

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
+types/+untyped/@DataStub/DataStub.m	Added maxDims property, refactored dimension retrieval to use io.space.getSize, moved get_space to private methods, updated subsref for varargout support, added updateSize and numArgumentsFromSubscript methods
+types/+untyped/+datapipe/BoundPipe.m	Simplified constructor to use DataStub.maxDims, added updateSize call after append operation, added type validation for stub property
+tests/+unit/dataStubTest.m	Moved test schema generation to TestClassSetup for efficiency, added new test for nested data indexing
+tests/+fixtures/ExtensionGenerationFixture.m	Added existence checks before deleting directories and files to prevent errors
+io/+space/getSize.m	New utility function that encapsulates HDF5 dimension retrieval and conversion logic

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