Fix #1592: Previous responses header collapsed state not retained across landscape changes

app/src/main/java/org/oppia/android/app/player/state/StateFragment.kt

@@ -170,5 +170,11 @@ class StateFragment :
       STATE_FRAGMENT_STATE_KEY,
       stateFragmentPresenter.getUserAnswerState()
     )
+    stateFragmentPresenter.saveExpandedState(outState)
+  }
+
+  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+    super.onViewCreated(view, savedInstanceState)
+    stateFragmentPresenter.restoreExpandedState(savedInstanceState)
   }
 }

app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt

@@ -1,6 +1,7 @@
 package org.oppia.android.app.player.state
 
 import android.content.Context
+import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -617,4 +618,14 @@ class StateFragmentPresenter @Inject constructor(
       SurveyQuestionName.NPS
     )
   }
+
+  /** Saves the state of the header. */
+  fun saveExpandedState(outState: Bundle) {
+    recyclerViewAssembler.saveExpandedState(outState)
+  }
+
+  /** Restore the state of the header. */
+  fun restoreExpandedState(savedInstanceState: Bundle?) {
+    recyclerViewAssembler.restoreExpandedState(savedInstanceState)
+  }
 }

app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt

@@ -2,6 +2,7 @@ package org.oppia.android.app.player.state
 
 import android.app.Application
 import android.content.Context
+import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.animation.AccelerateInterpolator
@@ -111,6 +112,7 @@ private typealias AudioUiManagerRetriever = () -> AudioUiManager?
 
 private const val CONGRATULATIONS_TEXT_VIEW_FADE_MILLIS: Long = 600
 private const val CONGRATULATIONS_TEXT_VIEW_VISIBLE_MILLIS: Long = 800
+private const val HAS_PREVIOUS_RESPONSES_EXPANDED_KEY = "hasPreviousResponsesExpanded"
 
 /**
  * An assembler for generating the list of view models to bind to the state player recycler view.
@@ -1548,4 +1550,15 @@ class StatePlayerRecyclerViewAssembler private constructor(
       }
     }
   }
+
+  /** Saves the expanded state to a Bundle. */
+  fun saveExpandedState(outState: Bundle) {
+    outState.putBoolean(HAS_PREVIOUS_RESPONSES_EXPANDED_KEY, hasPreviousResponsesExpanded)
+  }
+
+  /** Restores the expanded state from a Bundle. */
+  fun restoreExpandedState(savedInstanceState: Bundle?) {
+    hasPreviousResponsesExpanded =
+      savedInstanceState?.getBoolean(HAS_PREVIOUS_RESPONSES_EXPANDED_KEY, false) ?: false
+  }
 }

app/src/test/java/org/oppia/android/app/player/state/StateFragmentLocalTest.kt

@@ -1455,6 +1455,56 @@ class StateFragmentLocalTest {
     }
   }
 
+  @Test
+  fun testStateFragment_previousResponsesExpanded_retainedOnRotation() {
+    launchForExploration(FRACTIONS_EXPLORATION_ID_1).use { _ ->
+      startPlayingExploration()
+      playThroughFractionsState1()
+
+      submitTwoWrongAnswersForFractionsState2()
+
+      onView(withId(R.id.state_recycler_view)).perform(scrollToViewType(PREVIOUS_RESPONSES_HEADER))
+      onView(withId(R.id.previous_response_header)).perform(click())
+      testCoroutineDispatchers.runCurrent()
+
+      onView(withId(R.id.state_recycler_view))
+        .check(matchesChildren(withId(R.id.submitted_answer_container), times = 2))
+
+      // Rotate device to trigger configuration change
+      onView(isRoot()).perform(orientationLandscape())
+      testCoroutineDispatchers.runCurrent()
+
+      // Verify expanded state is retained after rotation
+      onView(withId(R.id.previous_response_header)).check(matches(isDisplayed()))
+      onView(withId(R.id.state_recycler_view))
+        .check(matchesChildren(withId(R.id.submitted_answer_container), times = 2))
+    }
+  }
+
+  @Test
+  fun testStateFragment_previousResponsesCollapsed_remainsCollapsedOnRotation() {
+    launchForExploration(FRACTIONS_EXPLORATION_ID_1).use { _ ->
+      startPlayingExploration()
+      playThroughFractionsState1()
+
+      submitTwoWrongAnswersForFractionsState2()
+
+      onView(withId(R.id.state_recycler_view)).perform(scrollToViewType(PREVIOUS_RESPONSES_HEADER))
+      testCoroutineDispatchers.runCurrent()
+
+      onView(withId(R.id.state_recycler_view))
+        .check(matchesChildren(withId(R.id.submitted_answer_container), times = 1))
+
+      // Rotate device to trigger configuration change
+      onView(isRoot()).perform(orientationLandscape())
+      testCoroutineDispatchers.runCurrent()
+
+      // Verify the header remains collapsed after rotation
+      onView(withId(R.id.state_recycler_view))
+        .check(matchesChildren(withId(R.id.submitted_answer_container), times = 1))
+    }
+  }
+
   @Test
   fun testStateFragment_stateWithoutHints_wait60s_noHintIsAvailable() {
     launchForExploration(FRACTIONS_EXPLORATION_ID_1).use {