tests: refactor TestWasapiDownloader_DownloadAndValidateFile for readability

[ndushay]

refactor to WasapiDownloader.getWasapiCrawlSelector() method

(e.g. instead of inline, make this a private method:

List<Integer> desiredCrawlIds = new ArrayList<Integer>();
desiredCrawlIds.add(Integer.valueOf("666"));
PowerMockito.when(mockCrawlSelector.getSelectedCrawlIds(0)).thenReturn(desiredCrawlIds);
PowerMockito.whenNew(WasapiCrawlSelector.class).withArguments(wasapiRespList).thenReturn(mockCrawlSelector)

maybe something similar with

• mockConnection
• wfile creation
• taking over System.err or System.out for testing
  (and other small tweaks that are easy and make tests more readable)