[fenix] Bug 1812580 - Wait for the layout cycle to complete before changing anchors

This comes to solve the issue seen in the error logs by adding the anchor
change done for the snackbar to the operation queue on thread Main thread.
Should allow to avoid chaning the snackbar's anchor in between onMeasure and
onLayout.

app/src/main/java/org/mozilla/fenix/components/FenixSnackbarBehavior.kt

@@ -60,18 +60,20 @@ class FenixSnackbarBehavior<V : View>(
         currentAnchorId = dependency?.id ?: View.NO_ID
         val params = snackbar.layoutParams as CoordinatorLayout.LayoutParams
 
-        if (dependency == null || (dependency.id == R.id.toolbar && toolbarPosition == ToolbarPosition.TOP)) {
-            // Position the snackbar at the bottom of the screen.
-            params.anchorId = View.NO_ID
-            params.anchorGravity = Gravity.NO_GRAVITY
-            params.gravity = Gravity.BOTTOM or Gravity.CENTER_HORIZONTAL
-        } else {
-            // Position the snackbar just above the anchor.
-            params.anchorId = dependency.id
-            params.anchorGravity = Gravity.TOP or Gravity.CENTER_HORIZONTAL
-            params.gravity = Gravity.TOP or Gravity.CENTER_HORIZONTAL
+        snackbar.post {
+            if (dependency == null || (dependency.id == R.id.toolbar && toolbarPosition == ToolbarPosition.TOP)) {
+                // Position the snackbar at the bottom of the screen.
+                params.anchorId = View.NO_ID
+                params.anchorGravity = Gravity.NO_GRAVITY
+                params.gravity = Gravity.BOTTOM or Gravity.CENTER_HORIZONTAL
+                snackbar.layoutParams = params
+            } else {
+                // Position the snackbar just above the anchor.
+                params.anchorId = dependency.id
+                params.anchorGravity = Gravity.TOP or Gravity.CENTER_HORIZONTAL
+                params.gravity = Gravity.TOP or Gravity.CENTER_HORIZONTAL
+                snackbar.layoutParams = params
+            }
         }
-
-        snackbar.layoutParams = params
     }
 }

app/src/test/java/org/mozilla/fenix/components/FenixSnackbarBehaviorTest.kt

@@ -9,6 +9,8 @@ import android.view.View
 import android.view.ViewGroup
 import android.widget.FrameLayout
 import androidx.coordinatorlayout.widget.CoordinatorLayout
+import io.mockk.every
+import io.mockk.mockk
 import mozilla.components.support.test.robolectric.testContext
 import org.junit.Assert.assertEquals
 import org.junit.Before
@@ -20,14 +22,20 @@ import org.mozilla.fenix.helpers.FenixRobolectricTestRunner
 
 @RunWith(FenixRobolectricTestRunner::class)
 class FenixSnackbarBehaviorTest {
-    private val snackbarParams = CoordinatorLayout.LayoutParams(0, 0)
-    private val snackbarContainer = FrameLayout(testContext)
+    private val snackbarContainer = mockk<FrameLayout>(relaxed = true)
+    private var snackbarLayoutParams = CoordinatorLayout.LayoutParams(0, 0)
     private val dependency = View(testContext)
     private val parent = CoordinatorLayout(testContext)
 
     @Before
     fun setup() {
-        snackbarContainer.layoutParams = snackbarParams
+        every { snackbarContainer.layoutParams } returns snackbarLayoutParams
+        every { snackbarContainer.post(any()) } answers {
+            // Immediately run the given Runnable argument
+            val action: Runnable = firstArg()
+            action.run()
+            true
+        }
         parent.addView(dependency)
     }
 
@@ -235,17 +243,14 @@ class FenixSnackbarBehaviorTest {
     }
 
     private fun assertSnackbarPlacementAboveAnchor(anchor: View = dependency) {
-        assertEquals(anchor.id, snackbarContainer.params.anchorId)
-        assertEquals(Gravity.TOP or Gravity.CENTER_HORIZONTAL, snackbarContainer.params.anchorGravity)
-        assertEquals(Gravity.TOP or Gravity.CENTER_HORIZONTAL, snackbarContainer.params.gravity)
+        assertEquals(anchor.id, snackbarLayoutParams.anchorId)
+        assertEquals(Gravity.TOP or Gravity.CENTER_HORIZONTAL, snackbarLayoutParams.anchorGravity)
+        assertEquals(Gravity.TOP or Gravity.CENTER_HORIZONTAL, snackbarLayoutParams.gravity)
     }
 
     private fun assertSnackbarIsPlacedAtTheBottomOfTheScreen() {
-        assertEquals(View.NO_ID, snackbarContainer.params.anchorId)
-        assertEquals(Gravity.NO_GRAVITY, snackbarContainer.params.anchorGravity)
-        assertEquals(Gravity.BOTTOM or Gravity.CENTER_HORIZONTAL, snackbarContainer.params.gravity)
+        assertEquals(View.NO_ID, snackbarLayoutParams.anchorId)
+        assertEquals(Gravity.NO_GRAVITY, snackbarLayoutParams.anchorGravity)
+        assertEquals(Gravity.BOTTOM or Gravity.CENTER_HORIZONTAL, snackbarLayoutParams.gravity)
     }
-
-    private val FrameLayout.params
-        get() = layoutParams as CoordinatorLayout.LayoutParams
 }