Feature/a in phas a distinct style

Why not just ```tests.push(cluster.tests)```?  Also, do you mean to use ```push``` and not ```concat```? Here's the difference.

```javascript
var a = [1, 2];
var b = [3, 4];

a.push(b); // [1, 2, [3, 4]]
a.concat(b); // [1, 2, 3, 4]
```