[fenix] For https://github.com/mozilla-mobile/fenix/issues/27055: check whether applied wallpaper name is blank

app/src/main/java/org/mozilla/fenix/home/HomeFragment.kt

@@ -945,7 +945,7 @@ class HomeFragment : Fragment() {
         when {
             !shouldEnableWallpaper() ||
                 (wallpaperName == lastAppliedWallpaperName && !orientationChange) -> return
-            wallpaperName == Wallpaper.defaultName -> {
+            Wallpaper.nameIsDefault(wallpaperName) -> {
                 binding.wallpaperImageView.isVisible = false
                 lastAppliedWallpaperName = wallpaperName
             }

app/src/main/java/org/mozilla/fenix/wallpapers/Wallpaper.kt

@@ -129,6 +129,14 @@ data class Wallpaper(
                 null
             }
         }
+
+        /**
+         * Check if a wallpaper name matches the default. Considers empty strings to be default
+         * since that likely means a wallpaper has never been set.
+         *
+         * @param name The name to check.
+         */
+        fun nameIsDefault(name: String): Boolean = name.isEmpty() || name == defaultName
     }
 
     /**

app/src/test/java/org/mozilla/fenix/wallpapers/WallpaperTest.kt

@@ -0,0 +1,28 @@
+package org.mozilla.fenix.wallpapers
+
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class WallpaperTest {
+    @Test
+    fun `GIVEN blank wallpaper name WHEN checking whether is default THEN is default`() {
+        val result = Wallpaper.nameIsDefault("")
+
+        assertTrue(result)
+    }
+
+    @Test
+    fun `GIVEN the default wallpaper is set to be shown WHEN checking whether the current wallpaper should be default THEN return true`() {
+        val result = Wallpaper.nameIsDefault("default")
+
+        assertTrue(result)
+    }
+
+    @Test
+    fun `GIVEN a custom wallpaper is set to be shown WHEN checking whether the current wallpaper should be default THEN return false`() {
+        val result = Wallpaper.nameIsDefault("wally world")
+
+        assertFalse(result)
+    }
+}