ThumbnailGeneratorFFmpeg implements ThumbnailGenerator { @Override public Single<File> generate(File video, int milliseconds) { return rxJavaVertx.executeBlockingObservable(generateInternal(video, milliseconds)).toSingle(); }  @Override Single<File> generate(File video, int milliseconds);  }
@Test public void testGenerate(TestContext context) { File video = new File("src/test/resources", "ThumbnailGeneratorFFmpegTest.webm"); assumeTrue(video.exists()); Async async = context.async(); generator.generate(video, 3_000).subscribe(converted -> { context.assertTrue(converted.exists()); context.assertTrue(converted.getName().endsWith(".jpg")); context.assertTrue(converted.length() > 0); async.complete(); }, context::fail); }