test(config): add test for config files using only per-capability specs

To prevent bugs like #2925 in the future.

spec/unit/taskScheduler_test.js

@@ -162,6 +162,27 @@ describe('the task scheduler', function() {
     expect(scheduler.numTasksOutstanding()).toEqual(0);
   });
 
+
+  it('should work with only capability-specific specs', function() {
+    var toAdd = {
+      specs: [
+      ],
+      multiCapabilities: [{
+        'browserName': 'chrome',
+        specs: 'spec/unit/data/fakespecC.js'
+      }]
+    };
+    var config = new ConfigParser().addConfig(toAdd).getConfig();
+    var scheduler = new TaskScheduler(config);
+
+    var task = scheduler.nextTask();
+    expect(task.capabilities.browserName).toEqual('chrome');
+    expect(task.specs.length).toEqual(1);
+
+    task.done();
+    expect(scheduler.numTasksOutstanding()).toEqual(0);
+  });
+
   it('should handle multiCapabilities with mixture of features', function() {
     var toAdd = {
       specs: [