Fix intermittent test failures of ModeTest

app/src/test/java/org/mozilla/fenix/home/ModeTest.kt

@@ -26,6 +26,7 @@ class ModeTest {
     private lateinit var browsingModeManager: BrowsingModeManager
     private lateinit var currentMode: CurrentMode
     private lateinit var dispatchModeChanges: (mode: Mode) -> Unit
+    private var dispatchModeChangesResult: Mode? = null
 
     @Before
     fun setup() {
@@ -33,7 +34,11 @@ class ModeTest {
         accountManager = mockk(relaxed = true)
         onboarding = mockk(relaxed = true)
         browsingModeManager = mockk(relaxed = true)
-        dispatchModeChanges = mockk(relaxed = true)
+
+        dispatchModeChangesResult = null
+        dispatchModeChanges = {
+            dispatchModeChangesResult = it
+        }
 
         every { context.components.backgroundServices.accountManager } returns accountManager
 
@@ -99,7 +104,7 @@ class ModeTest {
 
         currentMode.emitModeChanges()
 
-        verify { dispatchModeChanges(Mode.Normal) }
+        assertEquals(Mode.Normal, dispatchModeChangesResult)
     }
 
     @Test