Change setNodeData to throw an Error

The setNodeData method should throw an error if we try to set data for a
non-existing node.

Update tests and README

README.md

@@ -17,8 +17,8 @@ Nodes in the graph are just simple strings with optional data associated with th
  - `addNode(name, data)` - add a node in the graph with optional data. If `data` is not given, `name` will be used as data
  - `removeNode(name)` - remove a node from the graph
  - `hasNode(name)` - check if a node exists in the graph
- - `getNodeData(name)` - get the data associated with a node (will throw an Error if the node does not exist) 
- - `setNodeData(name, data)` - set the data for an existing node. It will do nothing if the node does not exist
+ - `getNodeData(name)` - get the data associated with a node (will throw an Error if the node does not exist)
+ - `setNodeData(name, data)` - set the data for an existing node (will throw an Error if the node does not exist)
  - `addDependency(from, to)` - add a dependency between two nodes (will throw an Error if one of the nodes does not exist)
  - `removeDependency(from, to)` - remove a dependency between two nodes
  - `dependenciesOf(name, leavesOnly)` - get an array containing the nodes that the specified node depends on (transitively). If `leavesOnly` is true, only nodes that do not depend on any other nodes will be returned in the array.
@@ -45,11 +45,11 @@ Dependency Cycles are detected when running `dependenciesOf`, `dependantsOf`, an
 
     graph.overallOrder(); // ['c', 'b', 'a']
     graph.overallOrder(true); // ['c']
-    
+
     graph.addNode('d', 'data');
-    
+
     graph.getNodeData('d'); // 'data'
-    
+
     graph.setNodeData('d', 'newData');
-    
-    graph.getNodeData('d'); // 'newData'
+
+    graph.getNodeData('d'); // 'newData'

lib/dep_graph.js

@@ -92,11 +92,13 @@ DepGraph.prototype = {
     }
   },
   /**
-   * Set the associated data for a given node name. If the node does not exist, this method will do nothing
+   * Set the associated data for a given node name. If the node does not exist, this method will throw an error
    */
   setNodeData:function (node, data) {
     if (this.hasNode(node)) {
       this.nodes[node] = data;
+    } else {
+      throw new Error('Node does not exist: ' + node);
     }
   },
   /**

specs/dep_graph_spec.js

@@ -66,12 +66,12 @@ describe('DepGraph', function () {
     expect(graph.getNodeData('Foo')).toBe('data2');
   });
 
-  it('should do nothing if we try to set data for a non-existing node', function () {
+  it('should throw an error if we try to set data for a non-existing node', function () {
     var graph = new DepGraph();
 
-    graph.setNodeData('Foo', 'data');
-
-    expect(graph.hasNode('Foo')).toBe(false);
+    expect(function () {
+      graph.setNodeData('Foo', 'data');
+    }).toThrow(new Error('Node does not exist: Foo'));
   });
 
   it('should throw an error if the node does not exists and we try to get data', function () {
@@ -299,4 +299,4 @@ describe('DepGraph', function () {
     expect(graph.dependenciesOf('a')).toEqual(['b']);
   });
 
-});
+});