ApkFileBrowser { public String verifyLatestApkFile(Context context, @Nullable String apkCheckSum) { if (apkCheckSum == null) { return null; } File file = getLatestApkFile(context); if (file != null) { if (apkCheckSum.equals(FileUtil.hexMd5(file))) { return file.getAbsolutePath(); } else { file.delete(); } } return null; } @Inject  ApkFileBrowser(FileBrowser fileBrowser,
            VersionHelper versionHelper); @Nullable String getFileName(Context context, String version, String apkFileName); @NonNull List<File> findAllPossibleFolders(Context context); String verifyLatestApkFile(Context context, @Nullable String apkCheckSum);  }
@Test public void testEnsureVerifyLatestApkFileReturnsNullWhenCheckSumNull() { ApkFileBrowser apkFileBrowser = new ApkFileBrowser(mockFileBrowser, new VersionHelper()); String path = apkFileBrowser.verifyLatestApkFile(mockContext, null); assertNull(path); }