### Question:
B2FileContentSource implements B2ContentSource { @Override public long getContentLength() throws IOException { return source.length(); } private  B2FileContentSource(File source,
                                String sha1); static Builder builder(File source); static B2FileContentSource build(File source); @Override String getSha1OrNull(); @Override Long getSrcLastModifiedMillisOrNull(); @Override long getContentLength(); @Override InputStream createInputStream();  }### Answer:
@Test public void testGetContentLengthReturnsZeroCuzFileDoesntExist() throws IOException { assertEquals(0, contentSource.getContentLength()); }