使用浓缩咖啡断言列表中项目的正确数量

Question

检查和断言列表视图是 android espresso 的预期大小的最佳方法是什么？

我写了这个匹配器，但不太知道如何将其集成到测试中。

public static Matcher<View> withListSize (final int size) {
    return new TypeSafeMatcher<View> () {
        @Override public boolean matchesSafely (final View view) {
            return ((ListView) view).getChildCount () == size;
        }

        @Override public void describeTo (final Description description) {
            description.appendText ("ListView should have " + size + " items");
        }
    };
}

Answer 1

想通了。

class Matchers {
  public static Matcher<View> withListSize (final int size) {
    return new TypeSafeMatcher<View> () {
      @Override public boolean matchesSafely (final View view) {
        return ((ListView) view).getCount () == size;
      }

      @Override public void describeTo (final Description description) {
        description.appendText ("ListView should have " + size + " items");
      }
    };
  }
}

如果需要列表中的一项，请将其放入实际的测试脚本中。

onView (withId (android.R.id.list)).check (ViewAssertions.matches (Matchers.withListSize (1)));

Answer 2

使用 espresso 计算列表中的项目数量有两种不同的方法： 第一个是上面提到的@CoryRoy - 使用TypeSafeMatcher，另一个是使用BoundedMatcher。

因为@CoryRoy已经展示了如何断言它，这里我想告诉你如何使用不同的匹配器获取（返回）数字。

public class CountHelper {

    private static int count;

    public static int getCountFromListUsingTypeSafeMatcher(@IdRes int listViewId) {
        count = 0;

        Matcher matcher = new TypeSafeMatcher<View>() {
            @Override
            protected boolean matchesSafely(View item) {
                count = ((ListView) item).getCount();
                return true;
            }

            @Override
            public void describeTo(Description description) {
            }
        };

        onView(withId(listViewId)).check(matches(matcher));

        int result = count;
        count = 0;
        return result;
    }

    public static int getCountFromListUsingBoundedMatcher(@IdRes int listViewId) {
        count = 0;

        Matcher<Object> matcher = new BoundedMatcher<Object, String>(String.class) {
            @Override
            protected boolean matchesSafely(String item) {
                count += 1;
                return true;
            }

            @Override
            public void describeTo(Description description) {
            }
        };

        try {
            // do a nonsense operation with no impact
            // because ViewMatchers would only start matching when action is performed on DataInteraction
            onData(matcher).inAdapterView(withId(listViewId)).perform(typeText(""));
        } catch (Exception e) {
        }

        int result = count;
        count = 0;
        return result;
    }

}

还想提一下，您应该使用

ListView#getCount()

而不是

ListView#getChildCount()

:

• getCount()

  - Adapter拥有的数据项数量，可能大于可见视图的数量。

• getChildCount()

  - ViewGroup 中的子级数量，可以被 ViewGroup 重用。

Answer 3

在 Kotlin 和 RecyclerView 中，我使用了这段代码，其灵感来自@Cory Roy 的答案。

internal object Matchers {
    fun withRecyclerViewSize(size: Int): TypeSafeMatcher<View?> {
        return object : TypeSafeMatcher<View?>() {
            override fun describeMismatchSafely(item: View?, mismatchDescription: Description?) {
                mismatchDescription?.appendText("RecyclerView has ${(item as RecyclerView).childCount} item(s)")
            }

            override fun describeTo(description: Description) {
                description.appendText("RecyclerView should have $size item(s)")
            }

            override fun matchesSafely(item: View?): Boolean {
                return (item as RecyclerView).adapter?.itemCount == size
            }
        }
    }
}

像这样使用：

val recyclerView = onView(withId(R.id.rv_students))
recyclerView.check(ViewAssertions.matches(Matchers.withRecyclerViewSize(5)));