android - フローを返す関数をテストする例はありますか>?

Question

というリポジトリ クラスに関数がありますgetAll()。私の質問は、この機能をテストするにはどうすればよいですか? getAll()関数内のコードは次のとおりです。

fun getAll(): Flow<PagingData<Movie>> {
        return Pager(
            config = PagingConfig(enablePlaceholders = false, pageSize = 20),
            pagingSourceFactory = { MoviesPagingSource(movieApiService) }
        ).flow
    }

これが MoviesPagingSource クラスの内部です。

import androidx.paging.PagingSource
import androidx.paging.PagingState
import com.oazisn.moviecatalog.data.local.entity.Movie

class MoviesPagingSource(
    private val service: MovieApiService,
) : PagingSource<Int, Movie>() {

    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Movie> {
        val page = params.key ?: 1
        return try {
            val response = service.getPopular(page)
            val movies = ArrayList<Movie>()
            response.results?.forEach { data ->
                movies.add(
                    Movie(
                        "https://image.tmdb.org/t/p/original${data?.posterPath}",
                        data?.title ?: "-",
                        data?.voteAverage ?: 0.0,
                        data?.id ?: 0
                    )
                )
            }
            LoadResult.Page(
                data = movies,
                prevKey = if (page == 1) null else page - 1,
                nextKey = if (page == response.totalPages) null else page + 1
            )
        } catch (exception: Exception) {
            LoadResult.Error(exception)
        }
    }

    override fun getRefreshKey(state: PagingState<Int, Movie>): Int? {
        // Try to find the page key of the closest page to anchorPosition, from
        // either the prevKey or the nextKey, but you need to handle nullability
        // here:
        //  * prevKey == null -> anchorPage is the first page.
        //  * nextKey == null -> anchorPage is the last page.
        //  * both prevKey and nextKey null -> anchorPage is the initial page, so
        //    just return null.
        return state.anchorPosition?.let { anchorPosition ->
            val anchorPage = state.closestPageToPosition(anchorPosition)
            anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
        }
    }
}

PagingDataPaging v3 Android ライブラリのクラスです。https://developer.android.com/topic/libraries/architecture/paging/v3-overview

これまでに試した単体テストは次のとおりです。

@Test
    fun getAll() {
        testCoroutineRule.runBlockingTest {
            val dummyList = listOf(
                MovieResultItem(
                    posterPath = "/6Wdl9N6dL0Hi0T1qJLWSz6gMLbd.jpg",
                    title = "Mortal Kombat",
                    voteAverage = 7.9,
                    id = 460465
                ),
                MovieResultItem(
                    posterPath = "/pgqgaUx1cJb5oZQQ5v0tNARCeBp.jpg",
                    title = "Godzilla vs. Kong",
                    voteAverage = 8.2,
                    id = 399566
                ),
                MovieResultItem(
                    posterPath = "/oBgWY00bEFeZ9N25wWVyuQddbAo.jpg",
                    title = "Nobody",
                    voteAverage = 8.5,
                    id = 615457
                ),
                MovieResultItem(
                    posterPath = "/tnAuB8q5vv7Ax9UAEje5Xi4BXik.jpg",
                    title = "Zack Snyder's Justice League",
                    voteAverage = 8.5,
                    id = 791373
                )
            )
            val dummyObject = ListBaseResponse(
                results = dummyList
            )

            `when`(movieApiService.getPopular(1)).thenReturn(dummyObject)

            val movies = ArrayList<Movie>()
            dummyObject.results?.forEach { data ->
                movies.add(
                    Movie(
                        "https://image.tmdb.org/t/p/original${data?.posterPath}",
                        data?.title ?: "-",
                        data?.voteAverage ?: 0.0,
                        data?.id ?: 0
                    )
                )
            }

            val response = repository.getAll()

            val repoResponseAsLiveData = response.asLiveData()
            assertEquals(movies, repoResponseAsLiveData.value)

        }
    }

結果は

java.lang.AssertionError: 
Expected :[Movie(poster=https://image.tmdb.org/t/p/original/6Wdl9N6dL0Hi0T1qJLWSz6gMLbd.jpg, title=Mortal Kombat, rating=7.9, id=460465, rated=, duration=, genre=, releaseDate=, desc=, director=, writers=, stars=, creator=), Movie(poster=https://image.tmdb.org/t/p/original/pgqgaUx1cJb5oZQQ5v0tNARCeBp.jpg, title=Godzilla vs. Kong, rating=8.2, id=399566, rated=, duration=, genre=, releaseDate=, desc=, director=, writers=, stars=, creator=), Movie(poster=https://image.tmdb.org/t/p/original/oBgWY00bEFeZ9N25wWVyuQddbAo.jpg, title=Nobody, rating=8.5, id=615457, rated=, duration=, genre=, releaseDate=, desc=, director=, writers=, stars=, creator=), Movie(poster=https://image.tmdb.org/t/p/original/tnAuB8q5vv7Ax9UAEje5Xi4BXik.jpg, title=Zack Snyder's Justice League, rating=8.5, id=791373, rated=, duration=, genre=, releaseDate=, desc=, director=, writers=, stars=, creator=)]
Actual   :null