address review: signal now playing with an event flow, not an int

app/src/test/kotlin/com/subtracks/ui/NowPlayingLauncherTest.kt

@@ -0,0 +1,27 @@
+package com.subtracks.ui
+
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.withTimeoutOrNull
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class NowPlayingLauncherTest {
+    @Test
+    fun aRequestMadeBeforeCollectionIsDelivered() =
+        runTest {
+            val launcher = NowPlayingLauncher()
+            launcher.request()
+            assertEquals(Unit, launcher.openNowPlaying.first())
+        }
+
+    @Test
+    fun repeatedRequestsCollapseToTheLatest() =
+        runTest {
+            val launcher = NowPlayingLauncher()
+            repeat(3) { launcher.request() }
+            assertEquals(Unit, launcher.openNowPlaying.first())
+            assertNull(withTimeoutOrNull(100) { launcher.openNowPlaying.first() })
+        }
+}