I've never used the @all directive and I'd like to test it properly with both Leo and LeoJS.
In leoPy.leo (LeoPyRef.leo) the node @file ../doc/leoAttic.txt contains the only @all directive that Leo uses.
A recent PR cleared most of the attic, but you can take a look at a "fuller" attic in the 6.7.4 branch.
The attic contains random bits of code, including perhaps section references with no corresponding section definition nodes.
So to test @all, just create an @file node with @all in the top node and include (in any child) a node with an undefined section reference.
Edward