Use the name of the class/function for `describe` and describe the behaviour you are testing in `it`. Use present tense to be consistent with already existing tests.

Each individual test should be independent, it must not use global/shared data.

Example:

```js
describe('Data.index()', function() {
  it('reports one package', function() {
    var registryData = givenDataWithSinglePackageVersion();
    var packages = registryData.index();
    expect(packages).to.be.length(1);
  });

  it('does not report packages with no versions', function(done) {
    var registryData = givenDataWithSinglePackageVersion('test-pkg', '0.0.1');
    registryData.deletePackage('test-pkg', '0.0.1', function() {
      // etc.
    });
  });
});
```