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

[jayneel-shah18]

This PR introduces a suite of tests for the i.biomass GRASS GIS module, covering a range of scenarios, including functionality validation, property testing, edge cases, and performance evaluation.

Key updates in this PR include:

• Functionality: Verify output raster existence and dimensions.
• Properties: Test linearity and latitude dependency.
• Edge Cases: Validate behavior with zero and extreme input values.
• Performance: Test large-scale processing.

Test Case Additions:

• Basic Functionality:

  • Validate the creation and existence of the biomass output raster.

• Advanced Properties:

  • Linearity: Verify output scales proportionally with input.
  • Latitude Dependency: Ensure biomass values vary reasonably with latitude.

• Edge Cases:

  • Handle all-zero input rasters.
  • Test extreme values for all parameters.

• Performance:

  • Assess processing of large input rasters.

[petrasovaa]

In other tests we use slightly lower precision which is sufficient. Also you can reduce the number of decimal places in the stats.

Suggested change

	raster=self.output_raster, reference=expected_stats, precision=1e-8
	raster=self.output_raster, reference=expected_stats, precision=1e-6

[jayneel-shah18]

I have changed it to check upto six decimal places and also reduced the number of decimal places in the stats.

[petrasovaa]

The test functions can be executed in undefined order, so in the setUpClass you create the initial inputs, but the individual test functions modify them, so make sure that's not going to be a problem.

[petrasovaa]

I think this setUp is not a bad idea but given many tests are anyway creating their own layers, this is being run wastefully, so I would compute the data at the beginning of each test. We are trying to make the tests run fast.

[echoix]

It's 5 seconds for now, some others in imagery take 1 second, some others take more.

[jayneel-shah18]

Thank you for the feedback! I have restructured the tests to address the feedback about efficiency. The setUp method has been removed, and input rasters are now created directly within each test as needed avoiding redundant computations and ensuring faster test execution.