[changed] paths to inherit parents

- paths that start with `/` are absolute like they
  used to be

- paths that don't start with `/` are now relative
  (meaning they inherit their parent path)

- assumed `path`s from `name`s are relative

closes remix-run#244

examples/animations/app.js

@@ -36,7 +36,7 @@ var Image = React.createClass({
 var routes = (
   <Routes>
     <Route handler={App}>
-      <Route name="image" path="/:service" handler={Image} addHandlerKey={true} />
+      <Route name="image" path=":service" handler={Image} addHandlerKey={true} />
     </Route>
   </Routes>
 );

examples/dynamic-segments/app.js

@@ -49,8 +49,8 @@ var Task = React.createClass({
 var routes = (
   <Route handler={App}>
     <Route name="user" path="/user/:userId" handler={User}>
-      <Route name="task" path="/user/:userId/tasks/:taskId" handler={Task}/>
-      <Redirect from="/user/:userId/todos/:taskId" to="task"/>
+      <Route name="task" path="tasks/:taskId" handler={Task}/>
+      <Redirect from="todos/:taskId" to="task"/>
     </Route>
   </Route>
 );

modules/helpers/Path.js

@@ -140,11 +140,25 @@ var Path = {
     return path;
   },
 
+  /**
+   * Returns true if the given path is absolute.
+   */
+  isAbsolute: function (path) {
+    return path.charAt(0) === '/';
+  },
+
   /**
    * Returns a normalized version of the given path.
    */
-  normalize: function (path) {
+  normalize: function (path, parentRoute) {
     return path.replace(/^\/*/, '/');
+  },
+
+  /**
+   * Joins two URL paths together.
+   */
+  join: function (a, b) {
+    return a.replace(/\/*$/, '/') + b;
   }
 
 };

modules/helpers/makePath.js

@@ -8,8 +8,8 @@ var Path = require('./Path');
  */
 function makePath(to, params, query) {
   var path;
-  if (to.charAt(0) === '/') {
-    path = Path.normalize(to); // Absolute path.
+  if (Path.isAbsolute(path)) {
+    path = Path.normalize(to);
   } else {
     var route = RouteStore.getRouteByName(to);
 

modules/stores/RouteStore.js

@@ -48,10 +48,18 @@ var RouteStore = {
       props.name || props.path
     );
 
+    var parentPath = (parentRoute && parentRoute.props.path) || '/';
+
     if ((props.path || props.name) && !props.isDefault && !props.catchAll) {
-      props.path = Path.normalize(props.path || props.name);
+      var path = props.path || props.name;
+
+      // Relative paths extend their parent.
+      if (!Path.isAbsolute(path))
+        path = Path.join(parentPath, path);
+
+      props.path = Path.normalize(path);
     } else {
-      props.path = (parentRoute && parentRoute.props.path) || '/';
+      props.path = parentPath;
 
       if (props.catchAll)
         props.path += '*';

specs/RouteStore.spec.js

@@ -28,6 +28,31 @@ describe('when a route is looked up by name', function () {
 });
 
 describe('when registering a route', function () {
+
+  describe('that starts with /', function() {
+    it('does not inherit the parent path', function() {
+      var child;
+      var route = Route({ name: 'home', handler: App },
+        child = Route({ path: '/foo', handler: App })
+      );
+      RouteStore.registerRoute(route);
+      expect(child.props.path).toEqual('/foo');
+      RouteStore.unregisterRoute(route);
+    });
+  });
+
+  describe('that does not start with /', function() {
+    it('inherits the parent path', function() {
+      var child;
+      var route = Route({ name: 'home', handler: App },
+        child = Route({ path: 'foo', handler: App })
+      );
+      RouteStore.registerRoute(route);
+      expect(child.props.path).toEqual('/home/foo');
+      RouteStore.unregisterRoute(route);
+    });
+  });
+
   describe('with no handler', function () {
     it('throws an Error', function () {
       expect(function () {