fix(linkml_files): correct GitHub raw/pages URLs and convert tests to pytest

[amc-corey-cox]

What

Two related changes to linkml_model/linkml_files.py and its tests:

1. Fix broken GitHub URL builders

GITHUB_IO_PATH_FOR and GITHUB_PATH_FOR (branch/latest) currently emit URLs that 404. The schema/artifact files are published under the linkml_model/ package directory on GitHub (both raw and GitHub Pages), but these builders omitted that path segment. LOCAL_PATH_FOR was unaffected because its base already points inside the package.

Verified before/after (live curl):

| Function | before | after |
| GITHUB_PATH_FOR(META, YAML, LATEST) | …/main/model/schema/meta.yaml → 404 | …/main/linkml_model/model/schema/meta.yaml → 200 |
| GITHUB_IO_PATH_FOR(META, YAML) | …/model/schema/meta.yaml → 404 | …/latest/linkml_model/model/schema/meta.yaml → 200 |

GITHUB_IO_PATH_FOR gains an optional version="latest" argument since the docs site is versioned (<version>/linkml_model/…). The signature change is backward-compatible.

Known limitation: the tag/release path (tag_to_commit) now also uses the linkml_model/ prefix, which is correct for all modern (v1.x) releases. Pre-restructure tags such as v0.0.1 stored artifacts at the repo root, so URLs built for those very old tags are correct in form but will not resolve. Layout-aware detection was deliberately skipped as overkill.

2. Convert tests/test_linkml_files.py to pytest

Replaces the unittest.TestCase style with functional pytest, and splits the monolithic test_basic_rules so each function (URL_FOR, LOCAL_PATH_FOR, GITHUB_IO_PATH_FOR, GITHUB_PATH_FOR) is covered separately. The live GitHub-API test is now opt-in via LINKML_TEST_GITHUB_API=1 (rate-limited / flaky in CI) instead of a hardcoded skip flag.

Context

This picks up the still-relevant pieces of the long-stale #201. The bulk of that PR (the Format/_Path refactor) already landed on main independently; the URL fix and pytest conversion did not. #201 will be closed as superseded, referencing this PR.

[Copilot]

Pull request overview

This pull request updates linkml_model/linkml_files.py to generate correct GitHub Raw and GitHub Pages URLs for published schema/artifact files (which live under the linkml_model/ package directory), and modernizes the associated test suite by converting it from unittest to pytest.

Changes:

• Fix GitHub raw URL construction to include the linkml_model/ path prefix (branch/latest and tag-resolved URLs).
• Add a version="latest" parameter to GITHUB_IO_PATH_FOR so GitHub Pages URLs can target versioned docs paths (<version>/linkml_model/...).
• Convert tests/test_linkml_files.py to pytest, split coverage by function, and make GitHub-API network tests opt-in.

Reviewed changes

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

File	Description
linkml_model/linkml_files.py	Updates GitHub URL builders to include the linkml_model/ package path; adds versioning support for GitHub Pages URLs.
tests/test_linkml_files.py	Migrates tests to pytest, updates expected URLs, and gates live GitHub API tests behind an environment variable.

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[matentzn]

This looks good, but I only partially understand this; would appreciate a quick @dalito look.

[dalito]

The way the corrected linkml_model/-prefixed raw and Pages URLs are constructed looks correct to me.