### Question:
ApiClient implements ICategoryProvider<W>, IMetadataProvider { @Override public Map<String, Collection<String>> requestCategories(W wiki, List<String> fullTitles, boolean showhidden) throws ApiException { Map<String, Collection<String>> categoryMap = new HashMap<>(); String clshow = showhidden ? null : "!hidden"; this.requestCategoriesRecursive(wiki.getApiUrl(), fullTitles, categoryMap, null, clshow); return categoryMap; } ApiClient(); @Override Map<String, Collection<String>> requestCategories(W wiki, List<String> fullTitles, boolean showhidden); @Override List<String> requestCategorymembers(final W wiki, final String fullTitle); Collection<Pair<String, String>> requestLinksBetween(W wiki, List<String> fullTitles); @Override Metadata requestMetadata(final IWiki wiki);  }### Answer:
@Test public void testRequestCategories() throws ApiException { final List<String> fullTitles = new ArrayList<>(); fullTitles.add(PAGE_1); fullTitles.add(PAGE_2); final Map<String, Collection<String>> result = this.client.requestCategories(wiki, fullTitles, true); assertNotNull(result); assertNotEquals(0, result.size()); }