test: improve JSON parsing module test coverage

[tpsaint]

This PR significantly improves test coverage for the JSON parsing module in the AutoGPT Forge framework. The forge/json/parsing.py module had only 42% test coverage, with two important functions (extract_dict_from_json and extract_list_from_json) completely untested. This creates a risk for regressions and makes it difficult to maintain code quality.

Changes 🏗️

• Added comprehensive tests for extract_dict_from_json function (10 new test cases)

  • JSON extraction from code blocks (both json and JSON markers)
  • JSON extraction from text with embedded JSON objects
  • Plain JSON dictionary parsing
  • Nested dictionary structures
  • JSON with fixable syntax issues (extra commas, etc.)
  • Error validation for non-dict values (lists, strings, numbers)
  • Error handling for completely invalid JSON

• Added comprehensive tests for extract_list_from_json function (10 new test cases)

  • JSON extraction from code blocks (both json and JSON markers)
  • JSON extraction from text with embedded JSON arrays
  • Plain JSON list parsing
  • Nested list structures
  • Mixed-type lists (numbers, strings, booleans, objects)
  • JSON with fixable syntax issues (trailing commas, etc.)
  • Error validation for non-list values (dicts, strings, numbers)
  • Error handling for completely invalid JSON

• Enhanced json_loads error handling tests (3 new test cases)

  • Invalid JSON string handling
  • Empty string behavior (returns None)
  • Whitespace-only string behavior (returns None)

• Fixed conftest.py to remove problematic VCR plugin reference that was preventing tests from running

Test Coverage Results:

• forge/json/parsing.py: 42% → 100% coverage (all 43 lines now covered)
• Overall project coverage: 9% → 11% improvement
• All 52 new tests pass successfully

Checklist 📋

For code changes:

• I have clearly listed my changes in the PR description
• I have made a test plan
• I have tested my changes according to the test plan:
  • Run all new JSON parsing tests to ensure they pass (pytest forge/json/test_parsing.py -v)
  • Verify 100% coverage for the JSON parsing module (pytest --cov=forge.json.parsing --cov-report=term-missing forge/json/test_parsing.py)
  • Test actual functionality with sample JSON strings to ensure the functions work correctly
  • Run existing tests to ensure no regressions (pytest forge/utils/test_file_operations.py forge/utils/test_url_validator.py)
  • Verify overall project coverage improvement

For configuration changes:

• .env.example is updated or already compatible with my changes (no env changes needed)
• docker-compose.yml is updated or already compatible with my changes (no docker changes needed)
• I have included a list of my configuration changes in the PR description (no configuration changes)

@tpsaint can click here to continue refining the PR