[fenix] For https://github.com/mozilla-mobile/fenix/issues/21540 fix and re-enable editCustomSearchEngineTest

app/src/androidTest/java/org/mozilla/fenix/ui/SmokeTest.kt

@@ -544,7 +544,6 @@ class SmokeTest {
         }
     }
 
-    @Ignore("Started failing: https://github.com/mozilla-mobile/fenix/issues/21540")
     @Test
     // Verifies setting as default a customized search engine name and URL
     fun editCustomSearchEngineTest() {

app/src/androidTest/java/org/mozilla/fenix/ui/robots/SettingsSubMenuSearchRobot.kt

@@ -21,6 +21,7 @@ import androidx.test.espresso.matcher.ViewMatchers.withId
 import androidx.test.espresso.matcher.ViewMatchers.withParent
 import androidx.test.espresso.matcher.ViewMatchers.withText
 import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.uiautomator.By
 import androidx.test.uiautomator.UiDevice
 import androidx.test.uiautomator.UiSelector
 import org.hamcrest.CoreMatchers
@@ -72,12 +73,56 @@ class SettingsSubMenuSearchRobot {
     fun selectAddCustomSearchEngine() = onView(withText("Other")).click()
 
     fun typeCustomEngineDetails(engineName: String, engineURL: String) {
-        mDevice.findObject(
-            UiSelector().resourceId("$packageName:id/edit_engine_name")
-        ).setText(engineName)
-        mDevice.findObject(
-            UiSelector().resourceId("$packageName:id/edit_search_string")
-        ).setText(engineURL)
+        mDevice.findObject(By.res("$packageName:id/edit_engine_name")).clear()
+        mDevice.findObject(By.res("$packageName:id/edit_engine_name")).setText(engineName)
+        mDevice.findObject(By.res("$packageName:id/edit_search_string")).clear()
+        mDevice.findObject(By.res("$packageName:id/edit_search_string")).setText(engineURL)
+
+        try {
+            assertTrue(
+                mDevice.findObject(
+                    UiSelector()
+                        .resourceId("$packageName:id/edit_engine_name")
+                        .text(engineName)
+                ).waitForExists(waitingTime)
+            )
+
+            assertTrue(
+                mDevice.findObject(
+                    UiSelector()
+                        .resourceId("$packageName:id/edit_search_string")
+                        .text(engineURL)
+                ).waitForExists(waitingTime)
+            )
+        } catch (e: AssertionError) {
+            println("The name or the search string were not set properly")
+
+            // Lets again set both name and search string
+            goBackButton().click()
+            openAddSearchEngineMenu()
+            selectAddCustomSearchEngine()
+
+            mDevice.findObject(By.res("$packageName:id/edit_engine_name")).clear()
+            mDevice.findObject(By.res("$packageName:id/edit_engine_name")).setText(engineName)
+            mDevice.findObject(By.res("$packageName:id/edit_search_string")).clear()
+            mDevice.findObject(By.res("$packageName:id/edit_search_string")).setText(engineURL)
+
+            assertTrue(
+                mDevice.findObject(
+                    UiSelector()
+                        .resourceId("$packageName:id/edit_engine_name")
+                        .text(engineName)
+                ).waitForExists(waitingTime)
+            )
+
+            assertTrue(
+                mDevice.findObject(
+                    UiSelector()
+                        .resourceId("$packageName:id/edit_search_string")
+                        .text(engineURL)
+                ).waitForExists(waitingTime)
+            )
+        }
     }
 
     fun openEngineOverflowMenu(searchEngineName: String) {