MultiPartEntityWriter implements EntityWriter { public String getContentType(Request request) { return MULTIPART + BOUNDARY; } MultiPartEntityWriter();   MultiPartEntityWriter(Serializer<MultiPart<Param>> binarySerializer, Serializer<MultiPart<Param>> textSerializer); String getContentType(Request request); int getContentLength(Request request); void writeTo(Request request, OutputStream outputStream);  }
@Test public void getContentTypeShouldReturnMultiPartWithBoundary(){ String actual = toTest.getContentType(null); assertTrue(actual.matches("multipart/form-data; boundary=[a-zA-Z0-9]{24}")); }