Only the first answer is accepted

app/src/androidTest/java/com/example/quickmax/MainActivityTest.kt

@@ -12,18 +12,16 @@ import androidx.core.view.get
 import androidx.test.espresso.ViewAction
 import androidx.test.espresso.UiController
 import androidx.test.espresso.action.ViewActions.click
-import androidx.test.espresso.assertion.ViewAssertions.matches
 import androidx.test.espresso.matcher.ViewMatchers.*
+import junit.framework.Assert.assertTrue
 import org.hamcrest.Matcher
 import org.junit.Before
 
-
 class MainActivityTest {
     @get:Rule
     val testRule = ActivityTestRule<MainActivity>(MainActivity::class.java)
     private lateinit var radioGroup: RadioGroup
 
-
     @Before
     fun init() {
         radioGroup = testRule.activity.radio_group
@@ -34,7 +32,9 @@ class MainActivityTest {
         val correctAnswerIndex = getCorrectAnswerIndex()
         val correctAnswerId = radioGroup[correctAnswerIndex].id
         onView(withId(correctAnswerId)).perform(click())
-        onView(withId(R.id.response)).check(matches(withText(R.string.response_correct)))
+
+        assertTrue(testRule.activity.supportFragmentManager.fragments.size == 1)
+        assertTrue(testRule.activity.supportFragmentManager.fragments[0] is ResponseCorrectFragment)
     }
 
     @Test
@@ -43,9 +43,20 @@ class MainActivityTest {
         val wrongAnswerIndex = if (correctAnswerIndex == 3) 2 else 3
         val wrongAnswerId = radioGroup[wrongAnswerIndex].id
         onView(withId(wrongAnswerId)).perform(click())
-        onView(withId(R.id.response)).check(matches(withText(R.string.response_wrong)))
+
+        assertTrue(testRule.activity.supportFragmentManager.fragments.size == 1)
+        assertTrue(testRule.activity.supportFragmentManager.fragments[0] is ResponseWrongFragment)
     }
 
+    @Test
+    fun only_fist_answer_accepted() {
+        onView(withId(radioGroup[0].id)).perform(click())
+        assertTrue(testRule.activity.supportFragmentManager.fragments.size == 1)
+        onView(withId(radioGroup[1].id)).perform(click())
+        assertTrue(testRule.activity.supportFragmentManager.fragments.size == 1)
+    }
+
+
     private fun getCorrectAnswerIndex(): Int {
         val options = getOptions()
         val correctAnswer = findSecondMax(options)

app/src/main/java/com/example/quickmax/MainActivity.kt

@@ -10,6 +10,7 @@ import kotlinx.android.synthetic.main.activity_main.*
 class MainActivity : AppCompatActivity() {
 
     var numberSet = NumberSet(4, 3)
+    private var toAcceptAnswer = true
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -29,6 +30,9 @@ class MainActivity : AppCompatActivity() {
     }
 
     private fun processAnswer(answer: Int) {
+        if (!toAcceptAnswer)
+            return
+        toAcceptAnswer = false
         val responseFragment:Fragment = if (numberSet.isCorrect(answer)) {
             ResponseCorrectFragment.newInstance()
         } else

app/src/main/res/layout/fragment_response_correct.xml

@@ -25,7 +25,6 @@
         app:srcCompat="@drawable/ic_double_arrow" />
 
     <TextView
-        android:id="@+id/response"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginStart="24dp"

app/src/main/res/layout/fragment_response_wrong.xml

@@ -11,7 +11,6 @@
     app:layout_constraintStart_toStartOf="parent">
 
     <ImageButton
-        android:id="@+id/imageButton"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginTop="8dp"
@@ -25,7 +24,6 @@
         app:srcCompat="@drawable/ic_double_arrow" />
 
     <TextView
-        android:id="@+id/response"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginStart="24dp"