Adding render tests for image fallback with feature constant expressions and addImage operation

[SnailBones]

As pointed out by @alexshalamov, the tests added in #11049 and #11359 contain no feature constant expressions, but are all using ["image", ["get", "icon"]]. So in this PR I add two tests that use constant values, i.e. ["image", "fav-bicycle-18"]

Since data and constant expressions are evaluated in different codepaths, these additional tests should improve test coverage in JS and Native and ensure that image fallback expressions work in all expected conditions.

I also add two tests ensuring image fallback works with sprites added through addImage (as opposed to images in the spritesheet) and make a small improvement to organization.

Launch Checklist

• briefly describe the changes in this PR
• apply changelog label ('bug', 'feature', 'docs', etc) or use the label 'skip changelog'

[SnailBones]

Added two more tests: /add-image and feature-state/add-image to test with the addImage operation. GL JS tests fail unless the layer is moved to addLayer, this suggests that the map doesn'trerender on addImage.

This is not an issue in Native, where both these tests pass, as do variants without using addLayer.

These tests pass even before this fix and without triggering a breakpoint in the second VertexVectors overload here.

[alexshalamov]

addLayer will trigger tile re-layout. Would it be possible to move layer definition to style definition? List of operations may be:

1. wait
2. add image
3. set feature state

Test will verify that updated set of images is used for property evaluation in the feature-state code path.

[SnailBones]

Thank you @alexshalamov!

I tried the test with the layer definition in the style definition as you describe (in place of the current "layers": []. This causes the test to pass in GL Native but fail in GL JS. I think this is from an issue unique to render tests in GL JS.

I see two ways around this:

• resolve this issue in GL JS to get consistent render test behavior
• add the test in GL Native only (and perhaps open an issue to address this in GL JS at a later date).

I think the latter in the simplest approach for now, what do you think?

[SnailBones]

I just tested out the changes you suggest, and they still don't seem to use the intended updateVertexVectors function in Native.

[karimnaaji]

Per chat with @SnailBones approving this PR as even though it's not a strict requirement for gl-native, it still has a fair amount of render test coverage increase.