Fix .shared classing

Now that Graph#parentWays is cached, the specialized Graph#parentStructure
method is no longer necessary.

This commit also demonstrates that it's relatively easy to write specs for
rendering now!

js/id/graph/graph.js

@@ -35,17 +35,6 @@ iD.Graph.prototype = {
         return transients[key] = fn.call(entity);
     },
 
-    parentStructure: function(ways) {
-        var nodes = {};
-        ways.forEach(function(w) {
-            _.uniq(w.nodes).forEach(function(n) {
-                if (typeof nodes[n.id] === 'undefined') nodes[n.id] = 0;
-                nodes[n.id]++;
-            });
-        });
-        return nodes;
-    },
-
     parentWays: function(entity) {
         var graph = this;
         return this.transient(entity, 'parentWays',
@@ -63,7 +52,6 @@ iD.Graph.prototype = {
     },
 
     parentRelations: function(entity) {
-        // This is slow and a bad hack.
         var graph = this;
         return this.transient(entity, 'parentRelations',
             function generateParentRelations() {

js/id/svg/vertices.js

@@ -9,8 +9,6 @@ iD.svg.Vertices = function() {
             }
         }
 
-        var parentStructure = graph.parentStructure(vertices);
-
         var groups = surface.select('.layer-hit').selectAll('g.vertex')
             .filter(filter)
             .data(vertices, iD.Entity.key);
@@ -28,7 +26,7 @@ iD.svg.Vertices = function() {
             .attr('r', 4);
 
         groups.attr('transform', iD.svg.PointTransform(projection))
-            .classed('shared', function(d) { return parentStructure[d.id] > 1; });
+            .classed('shared', function(entity) { return graph.parentWays(entity).length > 1; });
 
         // Selecting the following implicitly
         // sets the data (vertix entity) on the elements

test/index.html

@@ -139,6 +139,7 @@
     <script src="spec/renderer/hash.js"></script>
     <script src="spec/renderer/map.js"></script>
 
+    <script src="spec/svg/vertices.js"></script>
     <script src="spec/svg/tag_classes.js"></script>
 
     <script src="spec/ui/inspector.js"></script>

test/index_packaged.html

@@ -57,6 +57,7 @@
     <script src="spec/renderer/hash.js"></script>
     <script src="spec/renderer/map.js"></script>
 
+    <script src="spec/svg/vertices.js"></script>
     <script src="spec/svg/tag_classes.js"></script>
 
     <script src="spec/ui/inspector.js"></script>

test/spec/svg/vertices.js

@@ -0,0 +1,25 @@
+describe("iD.svg.Vertices", function () {
+    var surface,
+        projection = d3.geo.mercator(),
+        filter = d3.functor(true);
+
+    beforeEach(function () {
+        surface = d3.select(document.createElementNS('http://www.w3.org/2000/svg', 'svg'));
+
+        surface.append('g')
+            .attr('class', 'layer-hit');
+    });
+
+    // TODO: fill out
+
+    it("adds the .shared class to vertices that are members of two or more ways", function () {
+        var node = iD.Node({loc: [0, 0]}),
+            way1 = iD.Way({nodes: [node.id]}),
+            way2 = iD.Way({nodes: [node.id]}),
+            graph = iD.Graph([node, way1, way2]);
+
+        surface.call(iD.svg.Vertices(), graph, [node], filter, projection);
+
+        expect(surface.select('.vertex').classed('shared')).to.equal(true);
+    });
+});