assumeTrue(this.exists());
    }

    public ExecOutput exec(Object... args) {
        return new TestFileHelper(this).executeSuccess(Arrays.asList(args), null);
    }

    public ExecOutput execWithFailure(List<?> args, List<?> env) {
        return new TestFileHelper(this).executeFailure(args, env);
    }

    public ExecOutput execute(List<?> args, List<?> env) {