First Commit

libraries/mediaplayer/impl/build.gradle.kts

@@ -0,0 +1,34 @@
+import extension.setupDependencyInjection
+import extension.testCommonDependencies
+
+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2023, 2024 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+plugins {
+    id("io.element.android-library")
+}
+
+android {
+    namespace = "io.element.android.libraries.mediaplayer.impl"
+}
+
+setupDependencyInjection()
+
+dependencies {
+    api(projects.libraries.mediaplayer.api)
+    implementation(libs.androidx.media3.exoplayer)
+
+    implementation(projects.libraries.audio.api)
+    implementation(projects.libraries.core)
+    implementation(projects.libraries.di)
+
+    implementation(libs.coroutines.core)
+
+    testCommonDependencies(libs)
+    testImplementation(projects.libraries.audio.test)
+    testImplementation(libs.coroutines.core)
+}

libraries/mediaplayer/impl/src/main/kotlin/io/element/android/libraries/mediaplayer/impl/DefaultMediaPlayer.kt

@@ -0,0 +1,180 @@
+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2023-2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.mediaplayer.impl
+
+import androidx.media3.common.C
+import androidx.media3.common.MediaItem
+import androidx.media3.common.Player
+import dev.zacsweers.metro.ContributesBinding
+import dev.zacsweers.metro.SingleIn
+import io.element.android.libraries.audio.api.AudioFocus
+import io.element.android.libraries.audio.api.AudioFocusRequester
+import io.element.android.libraries.di.RoomScope
+import io.element.android.libraries.di.annotations.SessionCoroutineScope
+import io.element.android.libraries.mediaplayer.api.MediaPlayer
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.timeout
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+import kotlin.time.Duration.Companion.seconds
+
+/**
+ * Default implementation of [MediaPlayer] backed by a [SimplePlayer].
+ */
+@ContributesBinding(RoomScope::class)
+@SingleIn(RoomScope::class)
+class DefaultMediaPlayer(
+    private val player: SimplePlayer,
+    @SessionCoroutineScope
+    private val sessionCoroutineScope: CoroutineScope,
+    private val audioFocus: AudioFocus,
+) : MediaPlayer {
+    private val listener = object : SimplePlayer.Listener {
+        override fun onIsPlayingChanged(isPlaying: Boolean) {
+            _state.update {
+                it.copy(
+                    currentPosition = player.currentPosition,
+                    duration = duration,
+                    isPlaying = isPlaying,
+                )
+            }
+            if (isPlaying) {
+                job = sessionCoroutineScope.launch { updateCurrentPosition() }
+            } else {
+                audioFocus.releaseAudioFocus()
+                job?.cancel()
+            }
+        }
+
+        override fun onMediaItemTransition(mediaItem: MediaItem?) {
+            _state.update {
+                it.copy(
+                    currentPosition = player.currentPosition,
+                    duration = duration,
+                    mediaId = mediaItem?.mediaId,
+                )
+            }
+        }
+
+        override fun onPlaybackStateChanged(playbackState: Int) {
+            _state.update {
+                it.copy(
+                    isReady = playbackState == Player.STATE_READY,
+                    isEnded = playbackState == Player.STATE_ENDED,
+                    currentPosition = player.currentPosition,
+                    duration = duration,
+                )
+            }
+        }
+    }
+
+    init {
+        player.addListener(listener)
+    }
+
+    private var job: Job? = null
+
+    private val _state = MutableStateFlow(
+        MediaPlayer.State(
+            isReady = false,
+            isPlaying = false,
+            isEnded = false,
+            mediaId = null,
+            currentPosition = 0L,
+            duration = null,
+        )
+    )
+
+    override val state: StateFlow<MediaPlayer.State> = _state.asStateFlow()
+
+    @OptIn(FlowPreview::class)
+    override suspend fun setMedia(
+        uri: String,
+        mediaId: String,
+        mimeType: String,
+        startPositionMs: Long,
+    ): MediaPlayer.State {
+        // Must pause here otherwise if the player was playing it would keep on playing the new media item.
+        player.pause()
+        player.clearMediaItems()
+        player.setMediaItem(
+            MediaItem.Builder()
+                .setUri(uri)
+                .setMediaId(mediaId)
+                .setMimeType(mimeType)
+                .build(),
+            startPositionMs,
+        )
+        player.prepare()
+        // Will throw TimeoutCancellationException if the player is not ready after 1 second.
+        return state.timeout(1.seconds).first { it.isReady && it.mediaId == mediaId }
+    }
+
+    override fun play() {
+        audioFocus.requestAudioFocus(
+            requester = AudioFocusRequester.VoiceMessage,
+            onFocusLost = {
+                if (player.isPlaying()) {
+                    player.pause()
+                }
+            },
+        )
+        if (player.playbackState == Player.STATE_ENDED) {
+            // There's a bug with some ogg files that somehow report to
+            // have no duration.
+            // With such files, once playback has ended once, calling
+            // player.seekTo(0) and then player.play() results in the
+            // player starting and stopping playing immediately effectively
+            // playing no sound.
+            // This is a workaround which will reload the media file.
+            player.getCurrentMediaItem()?.let {
+                player.setMediaItem(it, 0)
+                player.prepare()
+            }
+        }
+        player.play()
+    }
+
+    override fun pause() {
+        player.pause()
+    }
+
+    override fun seekTo(positionMs: Long) {
+        player.seekTo(positionMs)
+        _state.update {
+            it.copy(currentPosition = player.currentPosition)
+        }
+    }
+
+    override fun close() {
+        player.release()
+    }
+
+    private suspend fun updateCurrentPosition() {
+        while (true) {
+            if (!_state.value.isPlaying) return
+            delay(100)
+            _state.update {
+                it.copy(currentPosition = player.currentPosition)
+            }
+        }
+    }
+
+    private val duration: Long?
+        get() = player.duration.let {
+            if (it == C.TIME_UNSET) null else it
+        }
+}

libraries/mediaplayer/impl/src/main/kotlin/io/element/android/libraries/mediaplayer/impl/SimplePlayer.kt

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2023-2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.mediaplayer.impl
+
+import android.content.Context
+import androidx.media3.common.MediaItem
+import androidx.media3.common.Player
+import androidx.media3.exoplayer.ExoPlayer
+import dev.zacsweers.metro.BindingContainer
+import dev.zacsweers.metro.ContributesTo
+import dev.zacsweers.metro.Provides
+import io.element.android.libraries.di.RoomScope
+import io.element.android.libraries.di.annotations.ApplicationContext
+
+/**
+ * A subset of media3 [Player] that only exposes the few methods we need making it easier to mock.
+ */
+interface SimplePlayer {
+    fun addListener(listener: Listener)
+    val currentPosition: Long
+    val playbackState: Int
+    val duration: Long
+    fun clearMediaItems()
+    fun setMediaItem(mediaItem: MediaItem, startPositionMs: Long)
+    fun getCurrentMediaItem(): MediaItem?
+    fun prepare()
+    fun play()
+    fun isPlaying(): Boolean
+    fun pause()
+    fun seekTo(positionMs: Long)
+    fun release()
+    interface Listener {
+        fun onIsPlayingChanged(isPlaying: Boolean)
+        fun onMediaItemTransition(mediaItem: MediaItem?)
+        fun onPlaybackStateChanged(playbackState: Int)
+    }
+}
+
+@ContributesTo(RoomScope::class)
+@BindingContainer
+object SimplePlayerModule {
+    @Provides
+    fun simplePlayerProvider(
+        @ApplicationContext context: Context,
+    ): SimplePlayer = DefaultSimplePlayer(ExoPlayer.Builder(context).build())
+}
+
+/**
+ * Default implementation of [SimplePlayer] backed by a media3 [Player].
+ */
+class DefaultSimplePlayer(
+    private val p: Player
+) : SimplePlayer {
+    override fun addListener(listener: SimplePlayer.Listener) {
+        p.addListener(object : Player.Listener {
+            override fun onIsPlayingChanged(isPlaying: Boolean) = listener.onIsPlayingChanged(isPlaying)
+            override fun onMediaItemTransition(mediaItem: MediaItem?, reason: Int) = listener.onMediaItemTransition(mediaItem)
+            override fun onPlaybackStateChanged(playbackState: Int) = listener.onPlaybackStateChanged(playbackState)
+        })
+    }
+
+    override val currentPosition: Long
+        get() = p.currentPosition
+    override val playbackState: Int
+        get() = p.playbackState
+    override val duration: Long
+        get() = p.duration
+
+    override fun clearMediaItems() = p.clearMediaItems()
+
+    override fun setMediaItem(mediaItem: MediaItem, startPositionMs: Long) = p.setMediaItem(mediaItem, startPositionMs)
+
+    override fun getCurrentMediaItem(): MediaItem? = p.currentMediaItem
+
+    override fun prepare() = p.prepare()
+
+    override fun play() = p.play()
+
+    override fun isPlaying() = p.isPlaying
+
+    override fun pause() = p.pause()
+
+    override fun seekTo(positionMs: Long) = p.seekTo(positionMs)
+
+    override fun release() = p.release()
+}

libraries/mediaplayer/impl/src/test/kotlin/io/element/android/libraries/mediaplayer/impl/DefaultMediaPlayerTest.kt

@@ -0,0 +1,430 @@
+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2023-2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.mediaplayer.impl
+
+import androidx.media3.common.MediaItem
+import androidx.media3.common.Player
+import app.cash.turbine.test
+import com.google.common.truth.Truth.assertThat
+import io.element.android.libraries.audio.api.AudioFocus
+import io.element.android.libraries.audio.api.AudioFocusRequester
+import io.element.android.libraries.mediaplayer.api.MediaPlayer
+import io.element.android.libraries.mediaplayer.test.FakeAudioFocus
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
+import kotlinx.coroutines.TimeoutCancellationException
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertThrows
+import org.junit.Test
+
+class DefaultMediaPlayerTest {
+    private val aMediaId = "mediaId"
+    private val aMediaItem = MediaItem.Builder().setMediaId(aMediaId).build()
+
+    @Test
+    fun `initial state`() = runTest {
+        val sut = createDefaultMediaPlayer()
+        sut.state.test {
+            val initialState = awaitItem()
+            assertThat(initialState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = null,
+                )
+            )
+        }
+    }
+
+    @Test
+    fun `start player will update the current position and pause it will stop`() = runTest {
+        val playLambda = lambdaRecorder<Unit> { }
+        val pauseLambda = lambdaRecorder<Unit> { }
+        val player = FakeSimplePlayer(
+            playLambda = playLambda,
+            pauseLambda = pauseLambda,
+        )
+        val requestAudioFocusResult = lambdaRecorder<AudioFocusRequester, () -> Unit, Unit> { _, _ -> }
+        val releaseAudioFocusResult = lambdaRecorder<Unit> {}
+        val audioFocus = FakeAudioFocus(
+            requestAudioFocusResult = requestAudioFocusResult,
+            releaseAudioFocusResult = releaseAudioFocusResult
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+            audioFocus = audioFocus,
+        )
+        sut.state.test {
+            val initialState = awaitItem()
+            assertThat(initialState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = null,
+                )
+            )
+            sut.play()
+            playLambda.assertions().isCalledOnce()
+            requestAudioFocusResult.assertions().isCalledOnce()
+            player.durationResult = 123L
+            player.simulateIsPlayingChanged(true)
+            val playingState = awaitItem()
+            assertThat(playingState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = true,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = 123,
+                )
+            )
+            player.currentPositionResult = 1L
+            assertThat(awaitItem()).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = true,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 1,
+                    duration = 123,
+                )
+            )
+            player.currentPositionResult = 2L
+            assertThat(awaitItem()).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = true,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 2,
+                    duration = 123,
+                )
+            )
+            player.pause()
+            pauseLambda.assertions().isCalledOnce()
+            player.simulateIsPlayingChanged(false)
+            releaseAudioFocusResult.assertions().isCalledOnce()
+            assertThat(awaitItem()).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 2,
+                    duration = 123,
+                )
+            )
+        }
+    }
+
+    @Test
+    fun `start player on ended playback will not invoke more methods if current media item is null`() = runTest {
+        val playLambda = lambdaRecorder<Unit> { }
+        val getCurrentMediaItemLambda = lambdaRecorder<MediaItem?> { null }
+        val player = FakeSimplePlayer(
+            playLambda = playLambda,
+            getCurrentMediaItemLambda = getCurrentMediaItemLambda,
+        )
+        val requestAudioFocusResult = lambdaRecorder<AudioFocusRequester, () -> Unit, Unit> { _, _ -> }
+        val audioFocus = FakeAudioFocus(
+            requestAudioFocusResult = requestAudioFocusResult,
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+            audioFocus = audioFocus,
+        )
+        sut.state.test {
+            val initialState = awaitItem()
+            assertThat(initialState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = null,
+                )
+            )
+            player.playbackStateResult = Player.STATE_ENDED
+            sut.play()
+            playLambda.assertions().isCalledOnce()
+            requestAudioFocusResult.assertions().isCalledOnce()
+        }
+    }
+
+    @Test
+    fun `start player on ended playback will invoke more methods if current media item is not null`() = runTest {
+        val playLambda = lambdaRecorder<Unit> { }
+        val prepareLambda = lambdaRecorder<Unit> { }
+        val getCurrentMediaItemLambda = lambdaRecorder<MediaItem?> { aMediaItem }
+        val setMediaItemLambda = lambdaRecorder<MediaItem, Long, Unit> { _, _ -> }
+        val requestAudioFocusResult = lambdaRecorder<AudioFocusRequester, () -> Unit, Unit> { _, _ -> }
+        val audioFocus = FakeAudioFocus(
+            requestAudioFocusResult = requestAudioFocusResult,
+        )
+        val player = FakeSimplePlayer(
+            playLambda = playLambda,
+            prepareLambda = prepareLambda,
+            setMediaItemLambda = setMediaItemLambda,
+            getCurrentMediaItemLambda = getCurrentMediaItemLambda,
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+            audioFocus = audioFocus,
+        )
+        sut.state.test {
+            val initialState = awaitItem()
+            assertThat(initialState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = null,
+                )
+            )
+            player.playbackStateResult = Player.STATE_ENDED
+            sut.play()
+            setMediaItemLambda.assertions().isCalledOnce().with(
+                value(aMediaItem),
+                value(0L),
+            )
+            prepareLambda.assertions().isCalledOnce()
+            playLambda.assertions().isCalledOnce()
+            requestAudioFocusResult.assertions().isCalledOnce()
+        }
+    }
+
+    @Test
+    fun `pause player invokes pause on the embedded player`() = runTest {
+        val pauseLambda = lambdaRecorder<Unit> { }
+        val player = FakeSimplePlayer(
+            pauseLambda = pauseLambda,
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+        )
+        sut.pause()
+        pauseLambda.assertions().isCalledOnce()
+    }
+
+    @Test
+    fun `close player invokes release on the embedded player`() = runTest {
+        val releaseLambda = lambdaRecorder<Unit> { }
+        val player = FakeSimplePlayer(
+            releaseLambda = releaseLambda,
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+        )
+        sut.close()
+        releaseLambda.assertions().isCalledOnce()
+    }
+
+    @Test
+    fun `seekTo invokes release on the embedded player`() = runTest {
+        val seekToLambda = lambdaRecorder<Long, Unit> { }
+        val player = FakeSimplePlayer(
+            seekToLambda = seekToLambda,
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+        )
+        sut.state.test {
+            awaitItem()
+            player.currentPositionResult = 33L
+            sut.seekTo(33L)
+            seekToLambda.assertions().isCalledOnce().with(value(33L))
+            val finalState = awaitItem()
+            assertThat(finalState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 33L,
+                    duration = null,
+                )
+            )
+        }
+    }
+
+    @Test
+    fun `onPlaybackStateChanged update the state`() = runTest {
+        val player = FakeSimplePlayer()
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+        )
+        sut.state.test {
+            val initialState = awaitItem()
+            assertThat(initialState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = null,
+                )
+            )
+            player.currentPositionResult = 44
+            player.durationResult = 123L
+            player.simulatePlaybackStateChanged(Player.STATE_READY)
+            val readyState = awaitItem()
+            assertThat(readyState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = true,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 44,
+                    duration = 123,
+                )
+            )
+            player.simulatePlaybackStateChanged(Player.STATE_ENDED)
+            val endedState = awaitItem()
+            assertThat(endedState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = true,
+                    mediaId = null,
+                    currentPosition = 44,
+                    duration = 123,
+                )
+            )
+        }
+    }
+
+    @Test
+    fun `setMedia with timeout error`() = runTest {
+        val pauseLambda = lambdaRecorder<Unit> { }
+        val clearMediaItemsLambda = lambdaRecorder<Unit> { }
+        val setMediaItemLambda = lambdaRecorder<MediaItem, Long, Unit> { _, _ -> }
+        val prepareLambda = lambdaRecorder<Unit> { }
+        val player = FakeSimplePlayer(
+            pauseLambda = pauseLambda,
+            clearMediaItemsLambda = clearMediaItemsLambda,
+            setMediaItemLambda = setMediaItemLambda,
+            prepareLambda = prepareLambda,
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+        )
+        sut.state.test {
+            val initialState = awaitItem()
+            assertThat(initialState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = null,
+                )
+            )
+            @Suppress("RunCatchingNotAllowed")
+            val result = runCatching {
+                sut.setMedia("uri", "mediaId", "mimeType", 12)
+            }
+            pauseLambda.assertions().isCalledOnce()
+            clearMediaItemsLambda.assertions().isCalledOnce()
+            setMediaItemLambda.assertions().isCalledOnce().with(
+                value(MediaItem.Builder().setUri("uri").setMediaId("mediaId").setMimeType("mimeType").build()),
+                value(12L),
+            )
+            prepareLambda.assertions().isCalledOnce()
+            assertThat(result.isFailure).isTrue()
+            assertThrows(TimeoutCancellationException::class.java) {
+                result.getOrThrow()
+            }
+        }
+    }
+
+    @Test
+    fun `setMedia success`() = runTest {
+        var player: FakeSimplePlayer? = null
+        val pauseLambda = lambdaRecorder<Unit> { }
+        val clearMediaItemsLambda = lambdaRecorder<Unit> { }
+        val setMediaItemLambda = lambdaRecorder<MediaItem, Long, Unit> { _, _ -> }
+        val prepareLambda = lambdaRecorder<Unit> {
+            player?.simulatePlaybackStateChanged(Player.STATE_READY)
+            player?.simulateMediaItemTransition(aMediaItem)
+        }
+        player = FakeSimplePlayer(
+            pauseLambda = pauseLambda,
+            clearMediaItemsLambda = clearMediaItemsLambda,
+            setMediaItemLambda = setMediaItemLambda,
+            prepareLambda = prepareLambda,
+        )
+        val sut = createDefaultMediaPlayer(
+            simplePlayer = player,
+        )
+        sut.state.test {
+            val initialState = awaitItem()
+            assertThat(initialState).isEqualTo(
+                MediaPlayer.State(
+                    isReady = false,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = null,
+                )
+            )
+            val state = sut.setMedia("uri", "mediaId", "mimeType", 12)
+            pauseLambda.assertions().isCalledOnce()
+            clearMediaItemsLambda.assertions().isCalledOnce()
+            setMediaItemLambda.assertions().isCalledOnce().with(
+                value(MediaItem.Builder().setUri("uri").setMediaId("mediaId").setMimeType("mimeType").build()),
+                value(12L),
+            )
+            prepareLambda.assertions().isCalledOnce()
+
+            val finalState = MediaPlayer.State(
+                isReady = true,
+                isPlaying = false,
+                isEnded = false,
+                mediaId = "mediaId",
+                currentPosition = 0,
+                duration = 0,
+            )
+            assertThat(awaitItem()).isEqualTo(
+                MediaPlayer.State(
+                    isReady = true,
+                    isPlaying = false,
+                    isEnded = false,
+                    mediaId = null,
+                    currentPosition = 0,
+                    duration = 0,
+                )
+            )
+            assertThat(awaitItem()).isEqualTo(finalState)
+            assertThat(state).isEqualTo(finalState)
+        }
+    }
+
+    private fun TestScope.createDefaultMediaPlayer(
+        simplePlayer: SimplePlayer = FakeSimplePlayer(),
+        audioFocus: AudioFocus = FakeAudioFocus(),
+    ): DefaultMediaPlayer = DefaultMediaPlayer(
+        player = simplePlayer,
+        sessionCoroutineScope = backgroundScope,
+        audioFocus = audioFocus,
+    )
+}

libraries/mediaplayer/impl/src/test/kotlin/io/element/android/libraries/mediaplayer/impl/FakeSimplePlayer.kt

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2024, 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.mediaplayer.impl
+
+import androidx.media3.common.MediaItem
+import io.element.android.tests.testutils.lambda.lambdaError
+
+class FakeSimplePlayer(
+    private val clearMediaItemsLambda: () -> Unit = { lambdaError() },
+    private val setMediaItemLambda: (MediaItem, Long) -> Unit = { _, _ -> lambdaError() },
+    private val getCurrentMediaItemLambda: () -> MediaItem? = { lambdaError() },
+    private val prepareLambda: () -> Unit = { lambdaError() },
+    private val playLambda: () -> Unit = { lambdaError() },
+    private val isPlayingLambda: () -> Boolean = { lambdaError() },
+    private val pauseLambda: () -> Unit = { lambdaError() },
+    private val seekToLambda: (Long) -> Unit = { lambdaError() },
+    private val releaseLambda: () -> Unit = { lambdaError() },
+) : SimplePlayer {
+    private val listeners = mutableListOf<SimplePlayer.Listener>()
+    override fun addListener(listener: SimplePlayer.Listener) {
+        listeners.add(listener)
+    }
+
+    var currentPositionResult: Long = 0
+    override val currentPosition: Long get() = currentPositionResult
+    var playbackStateResult: Int = 0
+    override val playbackState: Int get() = playbackStateResult
+    var durationResult: Long = 0
+    override val duration: Long get() = durationResult
+
+    override fun clearMediaItems() = clearMediaItemsLambda()
+    override fun setMediaItem(mediaItem: MediaItem, startPositionMs: Long) {
+        setMediaItemLambda(mediaItem, startPositionMs)
+    }
+
+    override fun getCurrentMediaItem(): MediaItem? = getCurrentMediaItemLambda()
+    override fun prepare() = prepareLambda()
+    override fun play() = playLambda()
+    override fun isPlaying() = isPlayingLambda()
+    override fun pause() = pauseLambda()
+    override fun seekTo(positionMs: Long) = seekToLambda(positionMs)
+    override fun release() = releaseLambda()
+
+    fun simulateIsPlayingChanged(isPlaying: Boolean) {
+        listeners.forEach { it.onIsPlayingChanged(isPlaying) }
+    }
+
+    fun simulateMediaItemTransition(mediaItem: MediaItem?) {
+        listeners.forEach { it.onMediaItemTransition(mediaItem) }
+    }
+
+    fun simulatePlaybackStateChanged(playbackState: Int) {
+        listeners.forEach { it.onPlaybackStateChanged(playbackState) }
+    }
+}