add hw2

node_modules/events/tests/once.js

@@ -0,0 +1,83 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('./common');
+var assert = require('assert');
+var EventEmitter = require('../');
+
+var e = new EventEmitter();
+
+e.once('hello', common.mustCall());
+
+e.emit('hello', 'a', 'b');
+e.emit('hello', 'a', 'b');
+e.emit('hello', 'a', 'b');
+e.emit('hello', 'a', 'b');
+
+function remove() {
+  assert.fail('once->foo should not be emitted');
+}
+
+e.once('foo', remove);
+e.removeListener('foo', remove);
+e.emit('foo');
+
+e.once('e', common.mustCall(function() {
+  e.emit('e');
+}));
+
+e.once('e', common.mustCall());
+
+e.emit('e');
+
+// Verify that the listener must be a function
+assert.throws(function() {
+  var ee = new EventEmitter();
+
+  ee.once('foo', null);
+}, /^TypeError: The "listener" argument must be of type Function. Received type object$/);
+
+{
+  // once() has different code paths based on the number of arguments being
+  // emitted. Verify that all of the cases are covered.
+  var maxArgs = 4;
+
+  for (var i = 0; i <= maxArgs; ++i) {
+    var ee = new EventEmitter();
+    var args = ['foo'];
+
+    for (var j = 0; j < i; ++j)
+      args.push(j);
+
+    ee.once('foo', common.mustCall(function() {
+      var params = Array.prototype.slice.call(arguments);
+      var restArgs = args.slice(1);
+      assert.ok(Array.isArray(params));
+      assert.strictEqual(params.length, restArgs.length);
+      for (var index = 0; index < params.length; index++) {
+        var param = params[index];
+        assert.strictEqual(param, restArgs[index]);
+      }
+  	}));
+
+    EventEmitter.prototype.emit.apply(ee, args);
+  }
+}