Add CLI test coverage for _extract_with_config

[Copilot]

Missing test coverage for the _extract_with_config() function in cli_extract.py. This function handles config-based CDF extraction but was only tested at the library level, not through the CLI interface.

Changes

• New test file tests/test_cli_extract.py with 17 tests covering:
  • Config-based extraction to CSV (column mapping, auto-detect job, invalid job, max records, specific variables)
  • Raw extraction without config to CSV and Parquet
  • Config-based extraction to Parquet
  • Append mode for both formats
  • Filename-to-column extraction

Example test

def test_extract_with_config_basic_csv(self, cli_runner, imap_cdf_file, tmp_path):
    config_file = tmp_path / "crump_config.yml"
    config_file.write_text("""
jobs:
  imap_mag:
    target_table: mag_data
    id_mapping:
      epoch: timestamp
    columns:
      vectors_x: vector_x
""")
    
    result = cli_runner.invoke(extract, [
        str(imap_cdf_file),
        "--config", str(config_file),
        "--job", "imap_mag",
    ])
    
    assert result.exit_code == 0
    # Verify transformed column names in output CSV

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Missing test coverage of _extract_with_config</issue_title>
<issue_description>- Add unit tests that exercises def _extract_with_config(...) function in the cli_extract.py file. This should pass a config file to the extract CLI command

• Add tests that extract with and without config to a parquet file
• check the tests pass, and if needed fix the code to amke them pass
• make sure linting and syntax checkers pass
  </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Missing test coverage of _extract_with_config #36

---

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[github-actions]

Test Results (Linux 3.14)

400 tests  +17   400 ✅ +17   37s ⏱️ +4s
  1 suites ± 0     0 💤 ± 0 
  1 files   ± 0     0 ❌ ± 0 

Results for commit dbb8d46. ± Comparison against base commit 69f7819.

♻️ This comment has been updated with latest results.

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.94%. Comparing base (69f7819) to head (dbb8d46).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #37      +/-   ##
==========================================
+ Coverage   84.78%   87.94%   +3.15%     
==========================================
  Files          17       17              
  Lines        2406     2406              
==========================================
+ Hits         2040     2116      +76     
+ Misses        366      290      -76     

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