[ruby/openssl] ssl: fix test case test_npn_advertised_protocol_too_long

The list of NPN protocols is validated in SSLContext#setup.

The assert_handshake_error is misleading. The client is unable to start
a handshake at all because the server is not running.

ruby/openssl@e8db6ffd9e

Author: rhenium

test/openssl/test_ssl.rb

@@ -1639,12 +1639,11 @@ def test_npn_protocol_selection_cancel
   def test_npn_advertised_protocol_too_long
     return unless OpenSSL::SSL::SSLContext.method_defined?(:npn_select_cb)
 
-    ctx_proc = Proc.new { |ctx| ctx.npn_protocols = ["a" * 256] }
-    start_server_version(:TLSv1_2, ctx_proc) { |port|
-      ctx = OpenSSL::SSL::SSLContext.new
-      ctx.npn_select_cb = -> (protocols) { protocols.first }
-      assert_handshake_error { server_connect(port, ctx) }
-    }
+    ctx = OpenSSL::SSL::SSLContext.new
+    assert_raise(OpenSSL::SSL::SSLError) do
+      ctx.npn_protocols = ["a" * 256]
+      ctx.setup
+    end
   end
 
   def test_npn_selected_protocol_too_long