feat: Augment schema parser error messages

[tbkr]

Description

Augment schema parser error messages. Now showing in which step of the schema file parsing the error is occurring.

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

🌈🌦️📖🚧 Documentation FDB 🚧📖🌦️🌈
https://sites.ecmwf.int/docs/fdb/pull-requests/PR-277

[Copilot]

Pull request overview

This PR aims to improve diagnosability of FDB schema parsing failures by adding higher-level context (which parsing phase failed) to schema parser error handling, and introduces a small test suite + fixtures to exercise broken schema inputs.

Changes:

• Add parsing-stage context around schema parsing exceptions (types parsing vs rules parsing).
• Wrap schema-load parsing errors with additional file-path context.
• Add a new parsing test target with schema fixtures (valid schema and several intentionally broken schemas).

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
src/fdb5/rules/SchemaParser.cc	Adds try/catch blocks and logging to annotate errors during type/rule parsing phases.
src/fdb5/rules/Schema.cc	Wraps StreamParser::Error to add schema path context when load fails.
tests/fdb/CMakeLists.txt	Registers the new parsing test subdirectory.
tests/fdb/parsing/CMakeLists.txt	Adds a new unit test target and copies parsing fixtures into the build tree.
tests/fdb/parsing/test_schema_parsing.cc	Adds unit tests intended to exercise broken/valid schema inputs.
tests/fdb/parsing/data/schema	Adds a valid schema fixture.
tests/fdb/parsing/data/schema_incomplete_rule	Adds a broken schema fixture (missing closing bracket).
tests/fdb/parsing/data/broken_schema_no_rule	Adds a fixture with only type definitions and no rules.
tests/fdb/parsing/data/broken_types_missing_semicolon	Adds a broken types fixture (missing semicolon).
tests/fdb/parsing/data/broken_types_no_name	Adds a broken types fixture (missing name).
tests/fdb/parsing/data/broken_types_no_type	Adds a broken types fixture (missing type).

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[tbkr]

@danovaro

[Ozaq]

This is a suggestion: fdb5::SchemaParser::Error may be directly used in a catch clause by callers of the API and as such may better be defined under API and not as nested type, e.g. fdb5::ConfigError or fdb5::SchemaError.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.91304% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 71.18%. Comparing base (dd9a587) to head (6399d0d).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
tests/fdb/parsing/test_schema_parsing.cc	98.18%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #277      +/-   ##
===========================================
+ Coverage    71.05%   71.18%   +0.13%     
===========================================
  Files          371      372       +1     
  Lines        23464    23550      +86     
  Branches      2458     2459       +1     
===========================================
+ Hits         16673    16765      +92     
+ Misses        6791     6785       -6     

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[tbkr]

The fix from #276 should be merged first.

[ChrisspyB]

I agree that 0 rules should be an error.