op: Implement 'filter_mode,minFilter' test in filter_mode.spec.ts

[Gyuyoung]

This PR adds a new test to ensure that the operation of minFilter works as expected.

Issue: #2023

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Requirements for PR author:

• All missing test coverage is tracked with "TODO" or .unimplemented().
• New helpers are /** documented */ and new helper files are found in helper_index.txt.
• Test behaves as expected in a WebGPU implementation. (If not passing, explain above.)

Requirements for reviewer sign-off:

• Tests are properly located in the test tree.
• Test descriptions allow a reader to "read only the test plans and evaluate coverage completeness", and accurately reflect the test code.
• Tests provide complete coverage (including validation control cases). Missing coverage MUST be covered by TODOs.
• Helpers and types promote readability and maintainability.

When landing this PR, be sure to make any necessary issue status updates.

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[Gyuyoung]

Hmm, I couldn't find a proper way to test the filter modes yet. I aimed to write a test that filter mode affected the expected colors in drawing the slanted plane. But, the filter modes(mipmapFilter first for now) didn't affect the expected result. Could you please give me any idea or comment on how to test the fooFilter affects the expected color?

[kainino0x]

It would be useful to visualize the colorAttachment. Unfortunately we never managed to add good facilities for this - I think I started writing some but never finished.

When running in a browser, you can hack in code to visualize it, e.g. add a canvas to the document.body and change drawSlantedPlane to get its attachment from getCurrentTexture instead of createTexture. Example:

Gyuyoung/cts@filter-mode-minFilter...kainino0x:cts:example-visualization
Here you can see there is a slight difference in the result (but it's subtle):

linear
nearest

[Gyuyoung]

Thank you for giving me more information. I don't find a way to test it yet. Let me take a look at this more.

[kainino0x]

FYI #2072 (comment)