nasm: add test

Closes Homebrew/homebrew#26551.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Formula/nasm.rb

@@ -12,4 +12,18 @@ class Nasm < Formula
     system "./configure", "--prefix=#{prefix}"
     system "make install install_rdf"
   end
+
+  test do
+    (testpath/"foo.s").write <<-EOS
+      mov eax, 0
+      mov ebx, 0
+      int 0x80
+    EOS
+
+    system "#{bin}/nasm", "foo.s"
+    code = File.open("foo", "rb") { |f| f.read.unpack("C*") }
+    expected = [0x66, 0xb8, 0x00, 0x00, 0x00, 0x00, 0x66, 0xbb,
+                0x00, 0x00, 0x00, 0x00, 0xcd, 0x80]
+    assert_equal expected, code
+  end
 end