add a test that extension is available during precompilation

Author: KristofferC

base/loading.jl

@@ -2153,6 +2153,7 @@ This can be used to reduce package load times. Cache files are stored in
 for important notes.
 """
 function compilecache(pkg::PkgId, internal_stderr::IO = stderr, internal_stdout::IO = stdout)
+    @info "Calling compilecache with pkg: $pkg"
     @nospecialize internal_stderr internal_stdout
     path = locate_package(pkg)
     path === nothing && throw(ArgumentError("$pkg not found during precompilation"))

test/project/Extensions/HasDepWithExtensions.jl/src/HasDepWithExtensions.jl

@@ -4,9 +4,12 @@ using HasExtensions: HasExtensions, HasExtensionsStruct
 using ExtDep: ExtDepStruct
 # Loading ExtDep makes the extension "Extension" load
 
+Base.get_extension(HasExtensions, :Extension) isa Module || error("extension not loaded during precompilation")
+
 function do_something()
     HasExtensions.foo(HasExtensionsStruct()) == 1 || error()
     HasExtensions.foo(ExtDepStruct()) == 2 || error()
+    Base.get_extension(HasExtensions, :Extension) isa Module || error("extension not loaded during __init__")
     return true
 end