Running with `imagemagick` unlinked causes the following:
```
$ brew test pango
Testing pango
==> /Users/sabae/.homebrew/Cellar/pango/1.32.6/bin/pango-view -t test-image --waterfall --rotate=10 --annotate=1 --header
pango-view: When running ImageMagick 'display' command: Failed to execute child process "display" (No such file or directory)
Error: pango: failed
```

I agree it would be best to have a better test, especially as this test fails for me even with `imagemagick` linked and all.  I will investigate other methods of testing pango.