Stop queueing the same episode twice in MockEpisodePlayer

Jetcaster/core/domain/src/main/java/com/example/jetcaster/core/player/MockEpisodePlayer.kt

@@ -120,24 +120,16 @@ class MockEpisodePlayer(private val mainDispatcher: CoroutineDispatcher) : Episo
             pause()
         }
 
-        // Keep the currently playing episode in the queue
+        // Everything that is not re-queued keeps its place behind the new episodes
+        val previousList = queue.value.filterNot { it in playerEpisodes }
+
+        // Keep the currently playing episode in the queue, unless the new list already
+        // contains it, otherwise it would show up twice
         val playingEpisode = _currentEpisode.value
-        var previousList: List<PlayerEpisode> = emptyList()
-        queue.update { queue ->
-            playerEpisodes.map { episode ->
-                if (queue.contains(episode)) {
-                    val mutableList = queue.toMutableList()
-                    mutableList.remove(episode)
-                    previousList = mutableList
-                } else {
-                    previousList = queue
-                }
-            }
-            if (playingEpisode != null) {
-                playerEpisodes + listOf(playingEpisode) + previousList
-            } else {
-                playerEpisodes + previousList
-            }
+        queue.value = if (playingEpisode != null && playingEpisode !in playerEpisodes) {
+            playerEpisodes + listOf(playingEpisode) + previousList
+        } else {
+            playerEpisodes + previousList
         }
 
         next()

Jetcaster/core/domain/src/test/kotlin/com/example/jetcaster/core/domain/player/MockEpisodePlayerTest.kt

@@ -23,6 +23,7 @@ import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.StandardTestDispatcher
 import kotlinx.coroutines.test.advanceTimeBy
 import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.runCurrent
 import kotlinx.coroutines.test.runTest
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
@@ -200,4 +201,36 @@ class MockEpisodePlayerTest {
         assertEquals(0, mockEpisodePlayer.playerState.value.timeElapsed.toMillis())
         assertEquals(testEpisodes[0], mockEpisodePlayer.currentEpisode)
     }
+
+    @Test
+    fun whenPlayListOfEpisodes_firstEpisodeIsNotQueuedTwice() = runTest(testDispatcher) {
+        // Same sequence of calls as LatestEpisodeViewModel.onPlayEpisodes()
+        mockEpisodePlayer.currentEpisode = testEpisodes[0]
+
+        mockEpisodePlayer.play(testEpisodes)
+        runCurrent()
+
+        assertEquals(testEpisodes[0], mockEpisodePlayer.currentEpisode)
+        assertEquals(testEpisodes.drop(1), mockEpisodePlayer.playerState.value.queue)
+    }
+
+    @Test
+    fun whenPlayListOfEpisodes_alreadyQueuedEpisodeIsNotDuplicated() = runTest(testDispatcher) {
+        val playingEpisode = PlayerEpisode(
+            uri = "currentEpisode",
+            duration = Duration.ofSeconds(60),
+        )
+        mockEpisodePlayer.currentEpisode = playingEpisode
+        mockEpisodePlayer.addToQueue(testEpisodes[0])
+        mockEpisodePlayer.addToQueue(testEpisodes[1])
+
+        // testEpisodes[1] is in the queue already, it should only be played once
+        mockEpisodePlayer.play(listOf(testEpisodes[1], testEpisodes[2]))
+        runCurrent()
+
+        assertEquals(
+            listOf(testEpisodes[2], playingEpisode, testEpisodes[0]),
+            mockEpisodePlayer.playerState.value.queue,
+        )
+    }
 }