Fix renameTo not taking property shorthands into account (#211)

* Fix `renameTo` not taking property shorthands into account

This fixes the `renameTo` helper method not properly renaming
object properties that are shorthands.

The previous version of the code would rename the property's
`value` correctly, but since `shorthand` was still set as `true`,
the output result would still be the old variable as a shorthand
property.

Now, if an identifier to be renamed is of type `Property` and
is a shorthand (but not a method), we flip the `shorthand` value
to be `false`.

* babel -> getParser()

* Add comment that explains why this works

src/collections/VariableDeclarator.js

@@ -134,6 +134,21 @@ const transformMethods = {
             scope = scope.parent;
           }
           if (scope) { // identifier must refer to declared variable
+
+            // It may look like we filtered out properties, 
+            // but the filter only ignored property "keys", not "value"s
+            // In shorthand properties, "key" and "value" both have an
+            // Identifier with the same structure.
+            const parent = path.parent.node;
+            if (
+              types.Property.check(parent) &&
+              parent.shorthand &&
+              !parent.method
+            )  {
+
+              path.parent.get('shorthand').replace(false);
+            }
+
             path.get('name').replace(newName);
           }
         });

src/collections/__tests__/VariableDeclarator-test.js

@@ -128,6 +128,37 @@ describe('VariableDeclarators', function() {
 
       expect(identifiers.length).toBe(1);
     });
+
+    it('properly renames a shorthand property that was using the old variable name', function() {
+      nodes = [recast.parse([
+        'var foo = 42;',
+        'var obj2 = {',
+        '  foo,',
+        '};',
+      ].join('\n'), {parser: getParser()}).program];
+
+      // Outputs:
+      // var newFoo = 42;
+      // var obj2 = {
+      //   foo: newFoo,
+      // };
+      Collection.fromNodes(nodes)
+        .findVariableDeclarators('foo').renameTo('newFoo');
+
+      expect(
+        Collection.fromNodes(nodes).find(types.Identifier, { name: 'newFoo' }).length
+      ).toBe(2);
+      expect(
+        Collection.fromNodes(nodes).find(types.Identifier, { name: 'foo' }).length
+      ).toBe(1);
+
+      expect(
+        Collection.fromNodes(nodes).find(types.Property).filter(prop => !prop.value.shorthand).length
+      ).toBe(1);
+      expect(
+        Collection.fromNodes(nodes).find(types.Property).filter(prop => prop.value.shorthand).length
+      ).toBe(0);
+    });
 
     it('does not rename React component prop name', function () {
       const declarators = Collection.fromNodes(nodes)