final String name = a.getDirectory().getName() + "-not-a-git";
final File base = a.getDirectory().getParentFile();
FileResolver resolver = new FileResolver(base, false);
try {
resolver.open(null, name);
} catch (RepositoryNotFoundException e) {
assertEquals("repository not found: " + name, e.getMessage());
Throwable why = e.getCause();
assertNotNull("has cause", why);