Add spec for required ports

spec/Component.coffee

@@ -0,0 +1,38 @@
+if typeof process isnt 'undefined' and process.execPath and process.execPath.indexOf('node') isnt -1
+  chai = require 'chai' unless chai
+  component = require '../src/lib/Component.coffee'
+  port = require '../src/lib/Port.coffee'
+  socket = require '../src/lib/InternalSocket.coffee'
+else
+  component = require 'noflo/src/lib/Component.js'
+  port = require 'noflo/src/lib/Port.js'
+  socket = require 'noflo/src/lib/InternalSocket.js'
+
+describe 'Component', ->
+  describe 'with required ports', (done) ->
+    it 'should throw an error upon receiving packet with an unattached required port', (done) ->
+      s1 = new socket
+      s2 = new socket
+      c = new component
+        inPorts:
+          requiredPort: new inport
+            required: true
+          optionalPort: new inport
+      c.inPorts.optionalPort.attach s2
+      run = ->
+        s2.send 'some-data'
+      chai.expect(run).to.throw()
+
+    it 'should be cool with an attached port', (done) ->
+      s1 = new socket
+      s2 = new socket
+      c = new component
+        inPorts:
+          requiredPort: new inport
+            required: true
+          optionalPort: new inport
+      c.inPorts.requiredPort.attach s1
+      c.inPorts.optionalPort.attach s2
+      run = ->
+        s2.send 'some-data'
+      chai.expect(run).to.not.throw()