Start experiment: associate key bindings with CSS selectors

KeyEventHandler holds references to BindingSets. The name "binding set"
is based on the concept of a CSS ruleset. The idea is to choose a key
binding for an event based on what selectors (match / most closely
contain) the event's target DOM node.

spec/atom/key-event-handler-spec.coffee

@@ -0,0 +1,37 @@
+KeyEventHandler = require 'key-event-handler'
+$ = require 'jquery'
+
+describe "KeyEventHandler", ->
+  handler = null
+
+  beforeEach ->
+    handler = new KeyEventHandler
+
+  fdescribe "handleKeypress", ->
+    describe "when there is a mapping in a selector that matches the event's element", ->
+      fragment = null
+      deleteCharHandler = null
+      insertCharHandler = null
+
+      beforeEach ->
+        handler.bindKeys '.command-mode', 'x': 'deleteChar'
+        handler.bindKeys '.insert-mode', 'x': 'insertChar'
+
+        fragment = $('<div class="command-mode">')
+        deleteCharHandler = jasmine.createSpy 'deleteCharHandler'
+        insertCharHandler = jasmine.createSpy 'insertCharHandler'
+        fragment.on 'deleteChar', deleteCharHandler
+        fragment.on 'insertChar', insertCharHandler
+
+      it "only triggers an event based on the key-binding in that selector", ->
+        handler.handleKeypress(keypressEvent('x', target: fragment[0]))
+        expect(deleteCharHandler).toHaveBeenCalled()
+        expect(insertCharHandler).not.toHaveBeenCalled()
+
+        deleteCharHandler.reset()
+        fragment.removeClass('command-mode').addClass('insert-mode')
+
+        handler.handleKeypress(keypressEvent('x', target: fragment[0]))
+        expect(deleteCharHandler).not.toHaveBeenCalled()
+        expect(insertCharHandler).toHaveBeenCalled()
+

spec/spec-helper.coffee

@@ -15,6 +15,9 @@ window.keydown = (pattern) ->
 window.createKeyEvent = (pattern) ->
   $.Event "keydown", atom.keyBinder.parseKeyPattern(pattern)
 
+window.keypressEvent = (pattern, properties={}) ->
+  $.Event "keypress", _.extend(atom.keyBinder.parseKeyPattern(pattern), properties)
+
 window.waitsForPromise = (fn) ->
   window.waitsFor (moveOn) ->
     fn().done(moveOn)