Encode OpenAPI server variable values

[Eduard van Valkenburg (eavanvalkenburg)]

Summary

• validate enum-constrained OpenAPI server variables before substitution
• percent-encode substituted server variable values, including defaults
• add regression tests for invalid enum values and reserved-character encoding

Testing

• uv run pytest tests/unit/connectors/openapi_plugin/test_sk_openapi.py -q

[Copilot]

Pull request overview

This PR hardens OpenAPI server URL construction for the Python OpenAPI plugin by validating enum-constrained server variables and percent-encoding substituted server variable values to prevent reserved characters from altering URL structure (e.g., host/path injection).

Changes:

• Added enum validation for server variables when provided via arguments during server URL substitution.
• Percent-encodes substituted server variable values (including defaults) during server URL construction.
• Added regression tests covering enum validation (argument path) and reserved-character/default encoding.

Reviewed changes

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

File	Description
python/semantic_kernel/connectors/openapi_plugin/models/rest_api_operation.py	Adds enum validation for argument-provided server variables and percent-encodes substituted values in server URL templates.
python/tests/unit/connectors/openapi_plugin/test_sk_openapi.py	Adds unit tests for enum validation and percent-encoding behavior in get_server_url.

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[github-actions]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
connectors/openapi_plugin/models
rest_api_operation.py	276	27	90%	101–102, 111–112, 121–122, 132, 141–142, 161–162, 171–172, 191–192, 228–229, 298, 306–309, 311, 355, 380, 382, 485
TOTAL	28945	5656	80%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
4071	23 💤	0 ❌	0 🔥	1m 49s ⏱️