### Question:
TempFileContentKeeper implements ContentKeeper { @Override public String getContentFileNameExt() { return contentProvider.getContentFileNameExt(); } TempFileContentKeeper(ContentProvider contentProvider); @Override InputStream getInputStream(); @Override String getMimeContentType(); @Override String getContentFileNameExt();  }### Answer:
@Test public void getContentFileNameExtTest() { when(mockContentProvider.getContentFileNameExt()).thenReturn("EXT"); assertEquals(sut.getContentFileNameExt(), "EXT"); }