As of now the MSVC scripts control if TAP tests are enabled or not using a boolean flag as $config->{tap_tests}. However, this flag is just taken into account in vcregress.pl, with the following issues: 1) config_default.pl does not list tap_tests, so it is unclear to users to enable them. People need to look into vcregress.pl as a start point.
Seems like a no-brainer.
2) GetFakeConfigure() does not translate $config->{tap_tests} into --enable-tap-tests, leading to pg_config not reporting it in CONFIGURE. This is inconsistent with what is done in ./configure.
That's worth doing but shouldn't be in the same patch, it makes it hard to see what actually changed. Yes, that's a nitpick, but it makes a 1-liner patch into a lot more.