test: checking if error constructor is assert.AssertionError

PR-URL: https://github.com/nodejs/node/pull/9119
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

test/parallel/test-debug-agent.js

@@ -1,6 +1,12 @@
 'use strict';
 require('../common');
 const assert = require('assert');
+const debug = require('_debug_agent');
 
-assert.throws(() => { require('_debug_agent').start(); },
-  assert.AssertionError);
+assert.throws(
+  () => { debug.start(); },
+  function(err) {
+    return (err instanceof assert.AssertionError &&
+            err.message === 'Debugger agent running without bindings!');
+  }
+);