Add easy-to-use dependency checkers and module inspection

[timbernat]

Description

Many places in current and planned MuPT code will require specialize and potentially expensive-to-import non-stdlib dependencies, e.g.:

• openff-toolkit
• mbuild
• rdkit
• polymerizeit

Given the modular nature of the library, it would be unreasonable to ship every external dependency from every subpackage as the base set of required dependencies for mupt. Instead, it is desirable to provide mechanisms for contributors to declare dependencies up-front and provide callers with more targeted warnings and installation instructions when missing dependencies are encountered.

Further, tools for inspecting the presence and contents of other libraries or other even subpackages of mupt would be desirable for enhancing the developer experience. Use cases include loading pre-compiled data for unit testing or skipping tests (rather than failing them) if certain dependencies are missing,

Todos

Notable points that this PR has either accomplished or will accomplish.

• Provide utilities for checking dependencies
  • @requires-type decorator to pre-declare dependencies needed for function or class definitions
  • Provide custom Exception with targeted messages describing declared use case, calling module, and installation instruction if the latter applies
  • Functions for pre-checking if module(s) are installed without just raising ImportError
• Utilities for inspecting the contents of packages
  • Mechanisms for distinguishing packages vs modules
  • Mechanisms for reading non-code resources (e.g. data files) from packages

Questions

• Want to tighten up terminology and ensure "library", "module", and "package" are used consistently and correctly throughout

Status

• Apply dependency checks to places in current code which require external libraries
• Write tests for new functionality
  • Ensure tests pass on CI run
• Address Copilot suggestions
• Pass human-moderated review
• Ready to go

[codecov]

Codecov Report

❌ Patch coverage is 70.53571% with 33 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
mupt/mutils/imports/names.py	0.00%	20 Missing ⚠️
mupt/mutils/imports/dependencies.py	82.50%	7 Missing ⚠️
mupt/mutils/imports/inspection.py	81.25%	6 Missing ⚠️

📢 Thoughts on this report? Let us know!

[Copilot]

Pull request overview

This PR introduces a small mupt.mutils.imports utility subpackage to (a) check for optional dependencies without importing them and (b) inspect modules/packages and access package-shipped resources, along with tests and packaged test data to support these behaviors.

Changes:

• Added dependency-checking utilities (module_installed, modules_installed, @requires_modules) and a custom missing-dependency exception.
• Added module/package inspection helpers and package-resource path helpers.
• Added pytest coverage for new functionality and included mupt.tests.data as package data for resource-loading tests.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
pyproject.toml	Adds setuptools package-data config so test resources under mupt.tests.data are included.
mupt/mutils/imports/init.py	Introduces the new mutils.imports subpackage namespace.
mupt/mutils/imports/dependencies.py	Implements dependency presence checks, decorator enforcement, and a custom exception.
mupt/mutils/imports/inspection.py	Implements module/package inspection helpers (and calling-module lookup).
mupt/mutils/imports/names.py	Adds helpers for generating module name/label components.
mupt/mutils/imports/resources.py	Implements helpers for locating resources within a package.
mupt/tests/mutils/imports/init.py	Adds tests package init for the new test suite.
mupt/tests/mutils/imports/test_dependencies.py	Adds tests for dependency checking and decorator behavior.
mupt/tests/mutils/imports/test_inspection.py	Adds tests for module/package inspection behavior.
mupt/tests/mutils/imports/test_resources.py	Adds tests for package resource fetching using packaged test data.
mupt/tests/data/init.py	Defines mupt.tests.data as an importable package for resource tests.
mupt/tests/data/sample.dat	Sample packaged resource file used by tests.

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[timbernat]

@dwhswenson Poking for review when you have time; less urgent, but does streamline integration PRs going forward.

For some reason, I don't see an option to run tests thru CI on this PR, and rerunning the Action hangs indefinitely. Any idea what's going on?