如何使用 Espresso 计算 RecyclerView 项目

Question

使用 Espresso 和 Hamcrest，

如何计算 recyclerView 中可用的项目数？

示例：我想检查 5 个项目是否显示在特定的 RecyclerView 中（必要时滚动）。

Answer 1

这里是一个查看 RecyclerView 项目计数的示例 ViewAssertion

public class RecyclerViewItemCountAssertion implements ViewAssertion {
  private final int expectedCount;

  public RecyclerViewItemCountAssertion(int expectedCount) {
    this.expectedCount = expectedCount;
  }

  @Override
  public void check(View view, NoMatchingViewException noViewFoundException) {
    if (noViewFoundException != null) {
        throw noViewFoundException;
    }

    RecyclerView recyclerView = (RecyclerView) view;
    RecyclerView.Adapter adapter = recyclerView.getAdapter();
    assertThat(adapter.getItemCount(), is(expectedCount));
  }
}

然后使用这个断言

onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(5));

我已经开始编写一个库，它应该可以让 espresso 和 uiautomator 的测试更加简单。这包括用于 RecyclerView 操作和断言的工具。 https://github.com/nenick/espresso-macchiato 参见例如带有方法 assertItemCountIs(int) 的 EspRecyclerView

Answer 2

在@Stephane's answer 中添加一点语法糖。

public class RecyclerViewItemCountAssertion implements ViewAssertion {
    private final Matcher<Integer> matcher;

    public static RecyclerViewItemCountAssertion withItemCount(int expectedCount) {
        return withItemCount(is(expectedCount));
    }

    public static RecyclerViewItemCountAssertion withItemCount(Matcher<Integer> matcher) {
        return new RecyclerViewItemCountAssertion(matcher);
    }

    private RecyclerViewItemCountAssertion(Matcher<Integer> matcher) {
        this.matcher = matcher;
    }

    @Override
    public void check(View view, NoMatchingViewException noViewFoundException) {
        if (noViewFoundException != null) {
            throw noViewFoundException;
        }

        RecyclerView recyclerView = (RecyclerView) view;
        RecyclerView.Adapter adapter = recyclerView.getAdapter();
        assertThat(adapter.getItemCount(), matcher);
    }
}

用法：

    import static your.package.RecyclerViewItemCountAssertion.withItemCount;

    onView(withId(R.id.recyclerView)).check(withItemCount(5));
    onView(withId(R.id.recyclerView)).check(withItemCount(greaterThan(5)));
    onView(withId(R.id.recyclerView)).check(withItemCount(lessThan(5)));
    // ...

Answer 3

完成 nenick 回答并提供更灵活的解决方案来测试项目 cout 是否大于、小于...

public class RecyclerViewItemCountAssertion implements ViewAssertion {

    private final Matcher<Integer> matcher;

    public RecyclerViewItemCountAssertion(int expectedCount) {
        this.matcher = is(expectedCount);
    }

    public RecyclerViewItemCountAssertion(Matcher<Integer> matcher) {
        this.matcher = matcher;
    }

    @Override
    public void check(View view, NoMatchingViewException noViewFoundException) {
        if (noViewFoundException != null) {
            throw noViewFoundException;
        }

        RecyclerView recyclerView = (RecyclerView) view;
        RecyclerView.Adapter adapter = recyclerView.getAdapter();
        assertThat(adapter.getItemCount(), matcher);
    }

}

用法：

onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(5));
onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(greaterThan(5));
onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(lessThan(5));
// ...

Answer 4

经过验证的答案有效，但我们可以用一条线解决这个问题，而无需适配器意识：

onView(withId(R.id.your_recycler_view_id)).check(matches(hasChildCount(2)))

将your_recycler_view_id 替换为您的ID，将2 替换为要声明的号码。

Answer 5

基于@Sivakumar Kamichetty 的回答：

1. 从内部类中访问变量“COUNT”，需要声明为 final。
2. 不必要的线路：COUNT = 0;
3. 将COUNT 变量转移到一个元素数组中。
4. 变量result 是不必要的。

不好，但可以：

public static int getCountFromRecyclerView(@IdRes int RecyclerViewId) {
    final int[] COUNT = {0};
    Matcher matcher = new TypeSafeMatcher<View>() {
        @Override
        protected boolean matchesSafely(View item) {
            COUNT[0] = ((RecyclerView) item).getAdapter().getItemCount();
            return true;
        }
        @Override
        public void describeTo(Description description) {}
    };
    onView(allOf(withId(RecyclerViewId),isDisplayed())).check(matches(matcher));
    return COUNT[0];
}

Answer 6

我使用下面的方法来获取 RecyclerView 的计数

public static int getCountFromRecyclerView(@IdRes int RecyclerViewId) {
int COUNT = 0;
        Matcher matcher = new TypeSafeMatcher<View>() {
            @Override
            protected boolean matchesSafely(View item) {
                COUNT = ((RecyclerView) item).getAdapter().getItemCount();
                return true;
            }
            @Override
            public void describeTo(Description description) {
            }
        };
        onView(allOf(withId(RecyclerViewId),isDisplayed())).check(matches(matcher));
        int result = COUNT;
            COUNT = 0;
        return result;
    }

用法-

int itemsCount = getCountFromRecyclerView(R.id.RecyclerViewId);

然后执行断言检查 itemsCount 是否符合预期

Answer 7

您可以创建自定义BoundedMatcher：

object RecyclerViewMatchers {
    @JvmStatic
    fun hasItemCount(itemCount: Int): Matcher<View> {
        return object : BoundedMatcher<View, RecyclerView>(
            RecyclerView::class.java) {

            override fun describeTo(description: Description) {
                description.appendText("has $itemCount items")
            }

            override fun matchesSafely(view: RecyclerView): Boolean {
                return view.adapter.itemCount == itemCount
            }
        }
    }
}

然后像这样使用它：

onView(withId(R.id.recycler_view)).check(matches((hasItemCount(5))))

Answer 8

使用 ActivityScenarioRule 计数

@get: Rule
val activityScenarioRule = ActivityScenarioRule(ShowListActivity::class.java)
@Test
fun testItemCount(){
activityScenarioRule.scenario.onActivity { activityScenarioRule ->
    val recyclerView = activityScenarioRule.findViewById<RecyclerView(R.id.movieListRecyclerView)
    val itemCount = recyclerView.adapter?.itemCount?:0
    ....
    }
}