i.emissivity: added test file for i.emissivity module

[jayneel-shah18]

This PR introduces a comprehensive test suite for the i.emissivity GRASS GIS module. The test suite is designed to validate core functionality, assess statistical correctness, and handle edge cases to ensure robust module behavior.

Key Updates in this PR:

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• Validate raster output generation and behavior under different NDVI conditions.
• Ensure correct handling of masked regions.
• Test behavior with different spatial resolutions.
• Verify response to extreme NDVI values and partial null inputs.

Test Case Additions

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Basic Functionality

• NDVI Range Validity: Ensure correct emissivity values are generated for valid NDVI inputs (test_emissivity_ndvi_range).
• Masked Regions: Validate handling of irregularly shaped masks (test_complex_mask).

Advanced Properties

• Spatial Resolution Handling: Check that the module produces consistent results across different region resolutions (test_region_resolution).
• Null Value Handling: Assess behavior when NDVI contains null values (test_partial_null_values).
• Extreme NDVI Values: Test module response when NDVI is outside the valid range (test_extreme_ndvi_values).

Performance

• The test suite execution times:
  • Windows: 2.315s
  • macOS: 1.353s
  • Ubuntu: 1.868s

Future Enhancements

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• Performance benchmarking for large-scale regions.
• Stress testing with extreme parameter variations.

This test suite enhances the reliability of the i.emissivity module by covering a broad spectrum of cases. Looking forward to feedback and potential refinements!

[echoix]

You don't need to update the branch as much, if there's not a particular reason for it. The last merge hadn't even completed yet