custom_target relying on an external static dependency

[mtribiere]

Here is my setup:

builddir
meson.build
subprojects
 |
 +---- libTest
            |
            + meson.build
            + lib
               |
               + libTest.a

In the top meson.build I'm using a custom_target that needs the path to libTest.a a pre-compiled library obtained from Wrap. So here I need ../subproject../libTest/lib.

How could I do that? Thanks