car toasts: take turns instead of replacing each other

A new toast waits until the one on screen has had 2 seconds. Repeats restart the
visible toast, and a burst keeps only the newest three waiting.

gearslip/src/test/java/app/seb3thehacker/gearslip/car/CarToastsTest.kt

@@ -13,15 +13,30 @@ class CarToastsTest {
     @Before
     @After
     fun clearToast() {
-        CarToasts.message.value?.let(CarToasts::dismiss)
+        while (true) CarToasts.message.value?.let(CarToasts::dismiss) ?: break
     }
 
     @Test
-    fun expiredToastCannotDismissItsReplacement() {
+    fun aNewToastWaitsForTheOneOnScreen() {
         val owner = Any()
         CarToasts.show(owner, "First", CarToast.LENGTH_SHORT)
         val first = requireNotNull(CarToasts.message.value)
         CarToasts.show(owner, "Second", CarToast.LENGTH_LONG)
+
+        assertSame(first, CarToasts.message.value)
+        assertEquals(1, CarToasts.waiting.value)
+        CarToasts.dismiss(first)
+        assertEquals("Second", CarToasts.message.value?.text)
+        assertEquals(0, CarToasts.waiting.value)
+    }
+
+    @Test
+    fun expiredTimerCannotDismissItsReplacement() {
+        val owner = Any()
+        CarToasts.show(owner, "First", CarToast.LENGTH_SHORT)
+        val first = requireNotNull(CarToasts.message.value)
+        CarToasts.show(owner, "Second", CarToast.LENGTH_LONG)
+        CarToasts.dismiss(first)
         val second = requireNotNull(CarToasts.message.value)
 
         CarToasts.dismiss(first)
@@ -39,6 +54,7 @@ class CarToastsTest {
         val repeated = requireNotNull(CarToasts.message.value)
 
         assertNotSame(first, repeated)
+        assertEquals(0, CarToasts.waiting.value)
         CarToasts.dismiss(first)
         assertSame(repeated, CarToasts.message.value)
     }
@@ -49,14 +65,24 @@ class CarToastsTest {
         val browse = Any()
         CarToasts.show(nav, "Route saved", CarToast.LENGTH_SHORT)
         CarToasts.show(browse, "Added to playlist", CarToast.LENGTH_SHORT)
-        val latest = CarToasts.message.value
 
         CarToasts.clear(nav)
-        assertSame(latest, CarToasts.message.value)
+        assertEquals("Added to playlist", CarToasts.message.value?.text)
         CarToasts.clear(browse)
         assertNull(CarToasts.message.value)
     }
 
+    @Test
+    fun aBurstKeepsOnlyTheNewestFewWaiting() {
+        val owner = Any()
+        listOf("1", "2", "3", "4", "5", "6").forEach { CarToasts.show(owner, it, CarToast.LENGTH_SHORT) }
+
+        assertEquals("1", CarToasts.message.value?.text)
+        assertEquals(3, CarToasts.waiting.value)
+        CarToasts.message.value?.let(CarToasts::dismiss)
+        assertEquals("4", CarToasts.message.value?.text)
+    }
+
     @Test
     fun blankRequestsDoNotReplaceAVisibleMessage() {
         val owner = Any()
@@ -65,6 +91,7 @@ class CarToastsTest {
 
         CarToasts.show(owner, " \n\t", CarToast.LENGTH_LONG)
         assertSame(visible, CarToasts.message.value)
+        assertEquals(0, CarToasts.waiting.value)
     }
 
     @Test
@@ -72,8 +99,10 @@ class CarToastsTest {
         val owner = Any()
         CarToasts.show(owner, "Short", CarToast.LENGTH_SHORT)
         assertEquals(4_000L, CarToasts.message.value?.durationMs)
+        CarToasts.message.value?.let(CarToasts::dismiss)
         CarToasts.show(owner, "Long", CarToast.LENGTH_LONG)
         assertEquals(7_000L, CarToasts.message.value?.durationMs)
+        CarToasts.message.value?.let(CarToasts::dismiss)
         CarToasts.show(owner, "Unknown", Int.MAX_VALUE)
         assertEquals(4_000L, CarToasts.message.value?.durationMs)
     }