我正在尝试使用 AndroidJunit4 测试 RecyclerView，这是我的测试代码：
package com.kaushik.myredmart.ui;
// all includes
@RunWith(AndroidJUnit4.class)
public class ProductListActivityTest {
@Rule
public ActivityTestRule<ProductListActivity> rule = new ActivityTestRule<>(ProductListActivity.class);
@Test
public void ensureListViewIsPresent() throws Exception {
ProductListActivity activity = rule.getActivity();
View viewByIdw = activity.findViewById(R.id.productListView);
assertThat(viewByIdw,notNullValue());
assertThat(viewByIdw, instanceOf(RecyclerView.class));
RecyclerView productRecyclerView = (RecyclerView) viewByIdw;
RecyclerView.Adapter adapter = productRecyclerView.getAdapter();
assertThat(adapter, instanceOf(ProductAdapter.class));
}
}
我在检查适配器时遇到问题。尽管productRecyclerView通过了非空测试和RecyclerView实例，但最后一行出现以下错误：
java.lang.AssertionError:
Expected: an instance of com.kaushik.myredmart.adapter.ProductAdapter
but: null
at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
at org.junit.Assert.assertThat(Assert.java:956)
at org.junit.Assert.assertThat(Assert.java:923)
at com.kaushik.myredmart.ui.ProductListActivityTest.ensureListViewIsPresent(ProductListActivityTest.java:45)
代码中有什么问题？
从这一行来看：
预期：com.kaushik.myredmart.adapter.ProductAdapter 的实例
但是：空
人们可以得出这样的结论：
RecyclerView.Adapter adapter = productRecyclerView.getAdapter();
returns null，当没有执行时可能会发生productRecyclerView.setAdapter(adapter).
确保您在活动生命周期回调中正确设置适配器（即在onCreate()）。在我看来，您正在某些操作/回调后创建和设置适配器。
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