Catch2 tests coverage for MapLayerBaseModel and MapLayerModel

[kaustuvpokharel]

MapLayerBaseModel tests cover initial state, layer population on setProject, dynamic addition/removal via project signals, all five data roles, invalid index handling, list model parent contract, disabled state ignoring signal-driven changes, the disabled/project-switch/re-enable lifecycle, signal deduplication guards on setEnabled and setProject, and project switching
WHile,
MapLayerModel tests cover default state, alphabetical sorting, all geometry-type filters (PointLayer, LineLayer, PolygonLayer, NoGeometry, HasGeometry combined with PointLayer to reach the detectGeometry branch), filtersChanged signal deduplication, findLayer with valid/null/orphan inputs, get() with valid and invalid rows, disabled state, requiresTrackingAvailability with no TrackingModel, requiresTrackingAvailability with a TrackingModel present but no active tracking, and requiresTrackingAvailabilityChanged signal deduplication

##FIndings

• WritableLayer filter is not tested, QgsVectorLayer exposes no public setter for read-only state; it is provider driven and cannot be forced from test code using a memory provider
• Active tracking (Tracker::start) is also not tested here, since it requires a fully initialised QgsApplication stack which is not present in the unit test asofnow and causes a SIGSEGV

[qfield-fairy]

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Other Android architectures

• arm-neon
• x64
• x86
• all access arm64
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• all access x64
• all access x86

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[nirvn]

@kaustuvpokharel , you can test the writable filter by tweaking the readOnly property of the layer.

[nirvn]

Active tracking (Tracker::start) is also not tested here, since it requires a fully initialised QgsApplication stack which is not present in the unit test asofnow and causes a SIGSEGV

@kaustuvpokharel , you can get that by adding a #define QFIELDTEST_MAIN at the top of your test_*.cpp file (e.g. this https://github.com/opengisch/QField/blob/master/test/test_tracking.cpp#L18 ). If that's done and there is still a crash, the cause is somewhere else.

[nirvn]

What's in there looks good, I've added two comments to guide you to add the missing bits.