Looking to all calls of handle_feature_test_result:

429: cascade_reason is a join of install_plan.unsupported_features, and the if is guarded by that not being empty on 413.
447: cascade_reason is set to the install action display name
461: Actual isn't cascade.
477: Actual isn't cascade.
549: Actual isn't cascade.
557: It's not entirely clear to prove that failed_dependencies will be nonempty here. However, failed_dependencies is recalculating something already present in ExtendedBuildResult, unmet_dependencies, which is already closely associated with CascadedDueToMissingDependencies

Before:

test[core]:x64-windows resulted in the unexpected state cascade because the following dependencies did not build: vcpkg-fail-if-depended-upon:x64-windows

After:

test[core]:x64-windows was unexpectedly a cascading failure because the following dependencies are unavailable: vcpkg-fail-if-depended-upon[a]:x64-windows, vcpkg-fail-if-depended-upon[core]:x64-windows

…o avoid needing to name cascade_reason for non-cascade cases.

# Conflicts:
#	src/vcpkg/commands.test-features.cpp

…ascade we got.

…strings as input.

…eparate' feature tests. Ensure that the syntax for combination-fails and feature-fails are correct. Always talk about feature names with the port name for clarity.

…the first option in the combined test.