fix(test): make external model fixtures hermetic

[Rishabh060105]

Closes #153

Summary

This change makes the test suite hermetic for the remaining external-model paths.

It replaces live model downloads in the affected tests with cached @models... fixtures, following the same naming pattern already used in Concerto tests and existing Accord Project archive fixtures.

Changes

• add cached external Concerto model fixtures under test/models
• add a shared test helper to load vendored external models into a ModelManager
• mock external model fetches for the archive-based test path using cached local fixtures
• update TemplateMarkInterpreter.test.ts to stop calling updateExternalModels() at runtime
• update TemplateArchiveProcessor.test.ts to resolve external model fetches from local cached fixtures

Test

npm test -- --runInBand --coverage=false

Results:

• 11 test suites passed
• 63 tests passed
• 38 snapshots passed

[Rishabh060105]

Hi @mttrbrts, the fix follows the Concerto-style cached external model pattern.

What changed:

• vendored the required external models as cached @models... fixtures under test/models
• replaced the runtime updateExternalModels() dependency in TemplateMarkInterpreter.test.ts with local cached model loading
• added a shared helper for offline external model resolution in tests
• updated TemplateArchiveProcessor.test.ts to resolve external model fetches from cached local fixtures instead of live downloads

I also verified the full suite locally after the change:

npm test -- --runInBand --coverage=false

[github-actions]

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[Rishabh060105]

@github unstale

[devanshi00]

Hey @Rishabh060105, thanks for the PR!

One suggestion before merge: take a look at how cicero-template-library handles this same problem in test/render.test.mjs — it might be a cleaner pattern than fetch-mocking here.

Instead of intercepting fetch and vendoring copies of the external model files, it forces offline: true at the loader boundary: Template.fromDirectory(path, { offline: true }). That routes cicero-core to mm.validateModelFiles() (a local-only check) instead of mm.updateExternalModels() (the network call), so no HTTP request is ever made in the first place. It goes a step further and globally monkeypatches Template.prototype.validate to always pass offline: true, which protects against any internal validate() call elsewhere in the chain, not just the one call site you know about.

Might be worth considering here instead of (or alongside) the mockExternalModelFetches approach , curious what you think.

[Rishabh060105]

Hi @devanshi00, TemplateArchiveProcessor.test.ts now calls Template.fromDirectory(..., { offline: true }) and temporarily patches Template.prototype.validate to preserve offline: true for internal validation calls. The original method is restored afterward to avoid leaking the patch into other tests.

This removes the fetch interception entirely and ensures archive models are validated locally through validateModelFiles() without making HTTP requests.

For tests that create a ModelManager directly, offline: true cannot be used. Instead, the required external model files are loaded locally before the template model. This keeps the tests offline and preserves validation without adding dependencies. Currently, only the money model is needed.

Thank you for pointing it out!
Hi @mttrbrts, please review the pr, thank you!

[mttrbrts]

I worry about the effect of monkey-patching in scenarios where tests are executed in parallel.

Instead, do we understand why the Template.fromDirectory(templateDir, {offline: true}) doesn't work as expected?

[Rishabh060105]

Yes, Template.fromDirectory(..., { offline: true }) uses offline mode initially, but cicero-core later calls template.validate() without forwarding the option. validate() then falls back to updateExternalModels(), causing the network request.
Basically cicero-core is failing to pass offline:true to the template.validate() call.We probably need to fix cicero-core so the loader forwards offline into its final validation call.

About the monkeypatch: it works well for sequential tests but when tests are executed in parallel it modifies the global state as well.

[mttrbrts]

Are you referring to this line? https://github.com/accordproject/template-archive/blob/main/packages/cicero-core/src/templateloader.ts#L113

Yes, we should fix that, rather than hack it here.

[Rishabh060105]

Yes, that is the line. I also found the same issue in the final validation inside fromDirectory. I can open a template-archive PR to forward offline through both loader paths and add regression coverage.