Given rust (Some Rust code):
  fn main() {
      println!("Hello World\n")
  }

Execute (RustInfo - call it to see that it works):
  redir => m
  silent RustInfo
  redir END
  Log m

Execute (RustEmitAsm - see that we actually get assembly output):
  silent! w test.rs
  silent! e! test.rs
  redir => m
  silent! RustEmitAsm
  redir END
  AssertEqual 'asm', &filetype
  normal! ggVGy:q<CR>
  AssertEqual 1,(@" =~# '\V.section')
  bd
  call delete('test.rs')

# TODO: a lot more tests