test: refactor test-dgram-setBroadcast.js

This test wasn't actually working, as sockets were being closed,
allowing the test to exit before any assertions were actually
run. This commit refactors the test to maintain the same intended
semantics.

PR-URL: #11252
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-dgram-setBroadcast.js

@@ -4,36 +4,22 @@ const common = require('../common');
 const assert = require('assert');
 const dgram = require('dgram');
 
-const setup = () => {
-  return dgram.createSocket({type: 'udp4', reuseAddr: true});
-};
+{
+  // Should throw EBADF if the socket is never bound.
+  const socket = dgram.createSocket('udp4');
 
-const teardown = (socket) => {
-  if (socket.close)
-    socket.close();
-};
-
-const runTest = (testCode, expectError) => {
-  const socket = setup();
-  const assertion = expectError ? assert.throws : assert.doesNotThrow;
-  const wrapped = () => { testCode(socket); };
-  assertion(wrapped, expectError);
-  teardown(socket);
-};
+  assert.throws(() => {
+    socket.setBroadcast(true);
+  }, /^Error: setBroadcast EBADF$/);
+}
 
-// Should throw EBADF if socket is never bound.
-runTest((socket) => { socket.setBroadcast(true); }, /EBADF/);
+{
+  // Can call setBroadcast() after binding the socket.
+  const socket = dgram.createSocket('udp4');
 
-// Should not throw if broadcast set to false after binding.
-runTest((socket) => {
-  socket.bind(0, common.localhostIPv4, () => {
-    socket.setBroadcast(false);
-  });
-});
-
-// Should not throw if broadcast set to true after binding.
-runTest((socket) => {
-  socket.bind(0, common.localhostIPv4, () => {
+  socket.bind(0, common.mustCall(() => {
     socket.setBroadcast(true);
-  });
-});
+    socket.setBroadcast(false);
+    socket.close();
+  }));
+}