Added a backing unit test

d5e1a030929fbd8a725e0aef2f2bd0d60f80e4f6
commit d5e1a030929fbd8a725e0aef2f2bd0d60f80e4f6
diff --git a/test/tests/repository.js b/test/tests/repository.js
@@ -6,6 +6,7 @@ describe("Repository", function() {
   var newRepo = path.resolve("test/repos/newrepo");
 
   var Repository = require("../../lib/repository");
+  var Index = require("../../lib/index");
 
   before(function() {
     var test = this;
@@ -38,4 +39,10 @@ describe("Repository", function() {
       return Repository.open(newRepo);
     });
   });
+
+  it("can read the index", function() {
+    return this.repository.index().then(function(index) {
+      assert.ok(index instanceof Index);
+    });
+  });
 });