Tests do not run content of Lucene.java

**Description**:
The current unit testing does not import anything from `Lucene.java` when running tests. Instead, the logic performed there is mocked (adding/searching documents), and tests run on this. `IcatAnalyzer` is tested.

**Acceptance criteria**:
- [ ] Change tests actually test the code in `Lucene.java`
- [ ] Use a code coverage tool to ensure these tests are sufficient?