test: add tests for Socket.setNoDelay

test/parallel/test-net-socket-setnodelay.js

@@ -0,0 +1,43 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const net = require('net');
+
+const truthyValues = [true, 1, 'true', {}, []];
+const falseyValues = [false, 0, ''];
+const genSetNoDelay = (desiredArg) => (enable) => {
+  assert.strictEqual(enable, desiredArg);
+};
+
+// setNoDelay should default to true
+let socket = new net.Socket({
+  handle: {
+    setNoDelay: common.mustCall(genSetNoDelay(true))
+  }
+});
+socket.setNoDelay();
+
+socket = new net.Socket({
+  handle: {
+    setNoDelay: common.mustCall(genSetNoDelay(true), truthyValues.length)
+  }
+});
+truthyValues.forEach((testVal) => socket.setNoDelay(testVal));
+
+socket = new net.Socket({
+  handle: {
+    setNoDelay: common.mustCall(genSetNoDelay(false), falseyValues.length)
+  }
+});
+falseyValues.forEach((testVal) => socket.setNoDelay(testVal));
+
+// if a handler doesn't have a setNoDelay function it shouldn't be called.
+// In the case below, if it is called an exception will be thrown
+socket = new net.Socket({
+  handle: {
+    setNoDelay: null
+  }
+});
+const returned = socket.setNoDelay(true);
+assert.ok(returned instanceof net.Socket);