test.run yes -- what's it do?

[Ryan Schmidt]

I'm trying to figure out if "test.run yes" actually does anything.

For example, the port judy includes "test.run yes", but installing  
with debugging and verbose output on, I can find no evidence that any  
test is being run.

My interest stems from the fftw-3 portfile, which includes this:

post-build {
        cd ${worksrcpath}
        system "make check"
}

I assumed this was just because the port author at the time did not  
know about:

test.run yes
test.target check

but the post-build definitely does run "make check", whereas if I  
replace the post-build section with the above test.run and  
test.target directives, I don't think "make check" gets run.

I'm running MacPorts compiled from the 1.5 trunk, on an Intel Core 2  
Duo MacBook Pro.

Anyone know what's up?