Fix #2084: Handle 'none' severity value in TestResultDBRowSchema

[RamiNoodle733]

Summary

This PR fixes issue #2084 where the "none" severity value causes a validation error in TestResultDBRowSchema when using dbt-fusion.

Problem

dbt-fusion returns severity as the string "none" (lowercase) instead of null/None. This caused a validation error:

ERROR — Could not generate the report - Error: 1 validation error for TestResultDBRowSchema
severity
 none is not an allowed value (type=type_error.none.not_allowed)

Solution

Added a Pydantic validator normalize_severity to TestResultDBRowSchema that:

1. Converts the string "none" (case-insensitive) to Python None
2. Preserves other severity values as-is
3. Handles None values correctly

Changes

• Modified elementary/monitor/fetchers/tests/schema.py - Added normalize_severity validator
• Added tests/unit/monitor/fetchers/tests/test_schema.py - Comprehensive tests for severity validation

Testing

All 8 new tests pass:

• test_severity_error
• test_severity_warn
• test_severity_none_string_lowercase
• test_severity_none_string_uppercase
• test_severity_none_string_mixed_case
• test_severity_python_none
• test_severity_missing_field
• test_severity_empty_string

Fixes #2084

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Fixed severity field normalization to consistently handle different representations of null values across data adapters.

[github-actions]

👋 @RamiNoodle733
Thank you for raising your pull request.
Please make sure to add tests and document all user-facing changes.
You can do this by editing the docs files in this pull request.

[coderabbitai]

📝 Walkthrough

Walkthrough

The PR adds a pre-validator to the TestResultDBRowSchema that normalizes the severity field, converting string values of "none" (case-insensitive) and Python None to None, while preserving other values. Comprehensive unit tests validate the normalization behavior across multiple scenarios.

Changes

Cohort / File(s)	Summary
Severity Validation Logic elementary/monitor/fetchers/tests/schema.py	Adds a pre-validator using Pydantic's validator decorator that normalizes severity field values: converts string "none" (case-insensitive) to None, preserves Python None, and leaves other values unchanged.
Test Coverage tests/unit/monitor/fetchers/tests/test_schema.py	Introduces comprehensive unit tests for severity field handling with a base_test_result fixture and TestTestResultDBRowSchema class covering: preservation of "ERROR" and "WARN" values, normalization of various "none" case variations to None, handling of Python None, missing severity fields, and empty string edge cases.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A "none" string was causing quite the fright,
But the validator fixed it right!
Case-insensitive, None stays true,
Tests confirm what the schema will do. ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically references the issue being fixed (#2084) and describes the main change: handling 'none' severity values in TestResultDBRowSchema.
Linked Issues check	✅ Passed	The PR fully addresses the requirements from issue #2084 by implementing a validator that converts string 'none' to None, preserving other values, and includes comprehensive tests for the normalization logic.
Out of Scope Changes check	✅ Passed	All changes are within scope: the validator addition in schema.py and corresponding unit tests in test_schema.py directly address the reported validation error without introducing unrelated modifications.
Docstring Coverage	✅ Passed	Docstring coverage is 81.82% which is sufficient. The required threshold is 80.00%.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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