Add a request-token to identify which xblock html was rendered as part of the current request

[STUD-2903]

common/static/coffee/spec/xblock/core_spec.coffee

@@ -2,9 +2,21 @@ describe "XBlock", ->
   beforeEach ->
     setFixtures """
       <div>
-        <div class='xblock' id='vA' data-runtime-version="A" data-runtime-class="TestRuntime" data-init="initFnA" data-name="a-name"/>
+        <div class='xblock'
+             id='vA'
+             data-runtime-version="A"
+             data-runtime-class="TestRuntime"
+             data-init="initFnA"
+             data-name="a-name"
+        />
         <div>
-          <div class='xblock' id='vZ' data-runtime-version="Z" data-runtime-class="TestRuntime" data-init="initFnZ"/>
+          <div class='xblock'
+               id='vZ'
+               data-runtime-version="Z"
+               data-runtime-class="TestRuntime"
+               data-init="initFnZ"
+               data-request-token="req-token-z"
+          />
         </div>
         <div class='xblock' id='missing-version' data-init='initFnA' data-name='no-version'/>
         <div class='xblock' id='missing-init' data-runtime-version="A" data-name='no-init'/>
@@ -25,8 +37,11 @@ describe "XBlock", ->
       @fakeChildren = ['list', 'of', 'children']
       spyOn(XBlock, 'initializeBlocks').andReturn(@fakeChildren)
 
-      @vABlock = XBlock.initializeBlock($('#vA')[0])
-      @vZBlock = XBlock.initializeBlock($('#vZ')[0])
+      @vANode = $('#vA')[0]
+      @vZNode = $('#vZ')[0]
+
+      @vABlock = XBlock.initializeBlock(@vANode, 'req-token-a')
+      @vZBlock = XBlock.initializeBlock(@vZNode)
       @missingVersionBlock = XBlock.initializeBlock($('#missing-version')[0])
       @missingInitBlock = XBlock.initializeBlock($('#missing-init')[0])
 
@@ -35,8 +50,8 @@ describe "XBlock", ->
       expect(TestRuntime.vZ).toHaveBeenCalledWith()
 
     it "loads the right init function", ->
-      expect(window.initFnA).toHaveBeenCalledWith(@runtimeA, $('#vA')[0])
-      expect(window.initFnZ).toHaveBeenCalledWith(@runtimeZ, $('#vZ')[0])
+      expect(window.initFnA).toHaveBeenCalledWith(@runtimeA, @vANode)
+      expect(window.initFnZ).toHaveBeenCalledWith(@runtimeZ, @vZNode)
 
     it "loads when missing versions", ->
       expect(@missingVersionBlock.element).toBe($('#missing-version'))
@@ -53,15 +68,29 @@ describe "XBlock", ->
       expect(@vZBlock.name).toBeUndefined()
 
     it "attaches the element to the block", ->
-      expect(@vABlock.element).toBe($('#vA')[0])
-      expect(@vZBlock.element).toBe($('#vZ')[0])
+      expect(@vABlock.element).toBe(@vANode)
+      expect(@vZBlock.element).toBe(@vZNode)
       expect(@missingVersionBlock.element).toBe($('#missing-version')[0])
       expect(@missingInitBlock.element).toBe($('#missing-init')[0])
 
+    it "passes through the request token", ->
+      expect(XBlock.initializeBlocks).toHaveBeenCalledWith($(@vANode), 'req-token-a')
+      expect(XBlock.initializeBlocks).toHaveBeenCalledWith($(@vZNode), 'req-token-z')
+
+
   describe "initializeBlocks", ->
-    it "initializes children", ->
+    beforeEach ->
       spyOn(XBlock, 'initializeBlock')
 
+      @vANode = $('#vA')[0]
+      @vZNode = $('#vZ')[0]
+
+    it "initializes children", ->
       XBlock.initializeBlocks($('#jasmine-fixtures'))
-      expect(XBlock.initializeBlock).toHaveBeenCalledWith($('#vA')[0])
-      expect(XBlock.initializeBlock).toHaveBeenCalledWith($('#vZ')[0])
+      expect(XBlock.initializeBlock).toHaveBeenCalledWith(@vANode, undefined)
+      expect(XBlock.initializeBlock).toHaveBeenCalledWith(@vZNode, undefined)
+
+    it "only initializes matching request tokens", ->
+      XBlock.initializeBlocks($('#jasmine-fixtures'), 'req-token-z')
+      expect(XBlock.initializeBlock).not.toHaveBeenCalledWith(@vANode, jasmine.any(Object))
+      expect(XBlock.initializeBlock).toHaveBeenCalledWith(@vZNode, 'req-token-z')

common/static/coffee/src/xblock/core.coffee

@@ -1,9 +1,16 @@
 @XBlock =
   Runtime: {}
 
-  initializeBlock: (element) ->
+  ###
+  Initialize the javascript for a single xblock element, and for all of it's
+  xblock children that match requestToken. If requestToken is omitted, use the
+  data-request-token attribute from element, or use the request-tokens specified on
+  the children themselves.
+  ###
+  initializeBlock: (element, requestToken) ->
     $element = $(element)
-    children = @initializeBlocks($element)
+    requestToken = requestToken or $element.data('request-token')
+    children = @initializeBlocks($element, requestToken)
     runtime = $element.data("runtime-class")
     version = $element.data("runtime-version")
     initFnName = $element.data("init")
@@ -26,7 +33,17 @@
     $element.addClass("xblock-initialized")
     block
 
-  initializeBlocks: (element) ->
-    $(element).immediateDescendents(".xblock").map((idx, elem) =>
-      @initializeBlock elem
+  ###
+  Initialize all XBlocks inside element that were rendered with requestToken.
+  If requestToken is omitted, and element has a 'data-request-token' attribute, use that.
+  If neither is available, then use the request tokens of the immediateDescendent xblocks.
+  ###
+  initializeBlocks: (element, requestToken) ->
+    requestToken = requestToken or $(element).data('request-token')
+    if requestToken
+      selector = ".xblock[data-request-token='#{requestToken}']"
+    else
+      selector = ".xblock"
+    $(element).immediateDescendents(selector).map((idx, elem) =>
+      @initializeBlock(elem, requestToken)
     ).toArray()