They can be run using
Meta/serenity.sh test lagom TestFontHandling
which will build _all_ test binaries and then run TestFontHandling.
There's also
Meta/serenity.sh run lagom TestFontHandling
which will build just TestFontHandling and run it, but currently
in a way that it doesn't pass.
Finally, manually doing
Meta/serenity.sh build lagom TestFontHandling
followed by
(cd Tests/LibGfx; ../../Build/lagom/Tests/LibGfx/TestFontHandling)
will build and then run just that one test in a way that makes the test
pass.
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