regression test for mapbox-gl-native#7241

[ivovandongen]

Fixes #187

[ivovandongen]

@jfirebaugh Strangely enough this test case also succeeds against master although this is exactly the case that mapbox/mapbox-gl-native#7241 fixes.

[jfirebaugh]

@ivovandongen It looks like the unit test in #7242 also passes without the fix present. In this case, I'm seeing Style::onLayerVisibilityChanged() trigger both Update::RecalculateStyle and Update::Layout. The former results in enabled getting set to true, and then the tiles get loaded via style->updateTiles(parameters).

Is there some additional setup needed to trigger the issue that these tests are missing?

[ivovandongen]

@jfirebaugh I've been looking into this. I've fixed the unit test, so it fails on master in the map test. It turns out there is a specific sequence that needs to happen so that the cache is filled with invalid tiles.

To reproduce this in a render test I need to be able to call render after certain steps so that the tiles are pruned and put into cache. However, I can't seem to do that right now as the render function takes a callback function as a second argument:

TypeError: Second argument must be a callback function

[jfirebaugh]

@ivovandongen So the sequence is:

• Add visible layer, render
• Set non-visible, render
• Set visible, render

?

You should be able to simulate that same sequence in a render test using the wait command, which has the same effect as test::render in unit tests.

[ivovandongen]

@jfirebaugh That seems to be exactly the test I've implemented in 989fb6d. However, it doesn't seem to render on wait operations though (verified with some log statements).

I see in https://github.com/mapbox/mapbox-gl-native/blob/424c05be5e3fbd45e52d8e3a6cf048cbd5703b8d/platform/node/test/suite_implementation.js#L68 that there is a render call in wait. However, after a setVisiblity operation, the loaded state of the map/style/source doesn't change and render is never called, instead the next operation is performed immediately.

[jfirebaugh]

Looks like there are a couple of issues:

• The "wait" command is implemented using conditional logic that calls map.render() only if map.loaded() is false. I think we should change this to always use map.render() -- the expectation is that "wait" waits for a full render.
• The maximum size of the source tile cache ends up being computed as 0 for small viewports.

I'll push a fix for these issues to the branch.