有一个单元测试代码：

@Mock
    Client client;

    @Test
    public void test() {

        doAnswer(r -> {
            response.setData(data);
            return Mono.just(response);
        }).when(client).doSomething(any(Response.class));
        ...
        foo();
     }

在代码方法中，“doSomething”用法如下：

public void foo() {
        Response result = new Response();
        client.doSomething(result).map( resp -> {
            // THIS CODE IS NOT EXECUTED IN JUNIT TEST
            if (somelag) {
               ...
            }
            return resp;
        }
    }

问题：

如何在junit测试中以正确的方式执行这段代码？

备注：

• 在运行时它工作正常
• 问题与线程有关（可能）
• 在运行时有（reactor.core.publisher.Mono）

public final <R> Mono<R> map(Function<? super T, ? extends R> mapper) {
    return this instanceof Fuseable ? onAssembly(new MonoMapFuseable(this, mapper)) : onAssembly(new MonoMap(this, mapper));
}

• 在运行时：this instanceof Fuseable == false
• 在junit中this instanceof Fuseable == true
• 在方法（reactor.core.publisher.Mono）hook == null和Hooks.GLOBAL_TRACE == false中的j单元测试中

protected static <T> Mono<T> onAssembly(Mono<T> source) {
        Function<Publisher, Publisher> hook = Hooks.onEachOperatorHook;
        if (hook != null) {
            source = (Mono)hook.apply(source);
        }

        if (Hooks.GLOBAL_TRACE) {
            FluxOnAssembly.AssemblySnapshot stacktrace = new FluxOnAssembly.AssemblySnapshot((String)null, (Supplier)Traces.callSiteSupplierFactory.get());
            source = (Mono)Hooks.addAssemblyInfo(source, stacktrace);
        }

        return source;
    }