mock_settings.java

... 
    if (!isMockLocationEnabled)
        startActivity(new Intent(android.provider.Settings.ACTION_APPLICATION_DEVELOPMENT_SETTINGS));
...

private boolean isMockLocationEnabled() 
{
    boolean isMockLocation;
    try {
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            AppOpsManager opsManager = (AppOpsManager) mContext.getSystemService(Context.APP_OPS_SERVICE);
            isMockLocation = (Objects.requireNonNull(opsManager).checkOp(AppOpsManager.OPSTR_MOCK_LOCATION, android.os.Process.myUid(), BuildConfig.APPLICATION_ID)== AppOpsManager.MODE_ALLOWED);
        } else {
            isMockLocation = !android.provider.Settings.Secure.getString(mContext.getContentResolver(), "mock_location").equals("0");
        }
    } catch (Exception e) {
        return false;
    }
    return isMockLocation;
}