Fix part of #5070: Display empty answer message in ratio input interaction

app/src/main/AndroidManifest.xml

@@ -221,6 +221,7 @@
     <activity android:name=".app.testing.HtmlParserTestActivity" />
     <activity android:name=".app.testing.HomeTestActivity" />
     <activity android:name=".app.testing.InputInteractionViewTestActivity" />
+    <activity android:name=".app.testing.RatioInputInteractionViewTestActivity" />
     <activity android:name=".app.testing.ImageRegionSelectionTestActivity" />
     <activity android:name=".app.testing.ImageViewBindingAdaptersTestActivity" />
     <activity android:name=".app.testing.ListItemLeadingMarginSpanTestActivity" />

app/src/main/java/org/oppia/android/app/activity/ActivityComponentImpl.kt

@@ -77,6 +77,7 @@ import org.oppia.android.app.testing.NavigationDrawerTestActivity
 import org.oppia.android.app.testing.PoliciesFragmentTestActivity
 import org.oppia.android.app.testing.ProfileChooserFragmentTestActivity
 import org.oppia.android.app.testing.ProfileEditFragmentTestActivity
+import org.oppia.android.app.testing.RatioInputInteractionViewTestActivity
 import org.oppia.android.app.testing.SplashTestActivity
 import org.oppia.android.app.testing.SpotlightFragmentTestActivity
 import org.oppia.android.app.testing.StateAssemblerMarginBindingAdaptersTestActivity
@@ -149,6 +150,7 @@ interface ActivityComponentImpl :
   fun inject(imageRegionSelectionTestActivity: ImageRegionSelectionTestActivity)
   fun inject(imageViewBindingAdaptersTestActivity: ImageViewBindingAdaptersTestActivity)
   fun inject(inputInteractionViewTestActivity: InputInteractionViewTestActivity)
+  fun inject(ratioInputInteractionViewTestActivity: RatioInputInteractionViewTestActivity)
   fun inject(licenseListActivity: LicenseListActivity)
   fun inject(licenseTextViewerActivity: LicenseTextViewerActivity)
   fun inject(listItemLeadingMarginSpanTestActivity: ListItemLeadingMarginSpanTestActivity)

app/src/main/java/org/oppia/android/app/parser/StringToRatioParser.kt

@@ -29,6 +29,7 @@ class StringToRatioParser {
     val normalized = text.normalizeWhitespace()
     val ratio = parseRatioOrNull(normalized)
     return when {
+      normalized.isBlank() -> RatioParsingError.EMPTY_INPUT
       !normalized.matches(invalidRatioRegex) || ratio == null -> RatioParsingError.INVALID_FORMAT
       numberOfTerms != 0 && ratio.ratioComponentCount != numberOfTerms -> {
         RatioParsingError.INVALID_SIZE
@@ -77,7 +78,8 @@ class StringToRatioParser {
     INVALID_FORMAT(error = R.string.ratio_error_invalid_format),
     INVALID_COLONS(error = R.string.ratio_error_invalid_colons),
     INVALID_SIZE(error = R.string.ratio_error_invalid_size),
-    INCLUDES_ZERO(error = R.string.ratio_error_includes_zero);
+    INCLUDES_ZERO(error = R.string.ratio_error_includes_zero),
+    EMPTY_INPUT(error = R.string.ratio_error_empty_input);
 
     /**
      * Returns the string corresponding to this error's string resources, or null if there is none.

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

@@ -46,12 +46,18 @@ class RatioExpressionInputInteractionViewModel private constructor(
         override fun onPropertyChanged(sender: Observable, propertyId: Int) {
           errorOrAvailabilityCheckReceiver.onPendingAnswerErrorOrAvailabilityCheck(
             pendingAnswerError,
-            answerText.isNotEmpty()
+            inputAnswerAvailable = true // Allow blank answer submission.
           )
         }
       }
     errorMessage.addOnPropertyChangedCallback(callback)
     isAnswerAvailable.addOnPropertyChangedCallback(callback)
+
+    // Initializing with default values so that submit button is enabled by default.
+    errorOrAvailabilityCheckReceiver.onPendingAnswerErrorOrAvailabilityCheck(
+      pendingAnswerError = null,
+      inputAnswerAvailable = true
+    )
   }
 
   override fun getPendingAnswer(): UserAnswer = UserAnswer.newBuilder().apply {
@@ -67,23 +73,24 @@ class RatioExpressionInputInteractionViewModel private constructor(
     }
   }.build()
 
-  /** It checks the pending error for the current ratio input, and correspondingly updates the error string based on the specified error category. */
+  /**
+   * It checks the pending error for the current ratio input, and correspondingly
+   * updates the error string based on the specified error category.
+   */
   override fun checkPendingAnswerError(category: AnswerErrorCategory): String? {
-    if (answerText.isNotEmpty()) {
-      when (category) {
-        AnswerErrorCategory.REAL_TIME ->
-          pendingAnswerError =
-            stringToRatioParser.getRealTimeAnswerError(answerText.toString())
-              .getErrorMessageFromStringRes(resourceHandler)
-        AnswerErrorCategory.SUBMIT_TIME ->
-          pendingAnswerError =
-            stringToRatioParser.getSubmitTimeError(
-              answerText.toString(),
-              numberOfTerms = numberOfTerms
-            ).getErrorMessageFromStringRes(resourceHandler)
-      }
-      errorMessage.set(pendingAnswerError)
+    pendingAnswerError = when (category) {
+      AnswerErrorCategory.REAL_TIME ->
+        if (answerText.isNotEmpty())
+          stringToRatioParser.getRealTimeAnswerError(answerText.toString())
+            .getErrorMessageFromStringRes(resourceHandler)
+        else null
+      AnswerErrorCategory.SUBMIT_TIME ->
+        stringToRatioParser.getSubmitTimeError(
+          answerText.toString(),
+          numberOfTerms = numberOfTerms
+        ).getErrorMessageFromStringRes(resourceHandler)
     }
+    errorMessage.set(pendingAnswerError)
     return pendingAnswerError
   }
 

app/src/main/java/org/oppia/android/app/testing/InputInteractionViewTestActivity.kt

@@ -17,15 +17,13 @@ import org.oppia.android.app.model.InputInteractionViewTestActivityParams.MathIn
 import org.oppia.android.app.model.InputInteractionViewTestActivityParams.MathInteractionType.NUMERIC_EXPRESSION
 import org.oppia.android.app.model.InputInteractionViewTestActivityParams.MathInteractionType.UNRECOGNIZED
 import org.oppia.android.app.model.Interaction
-import org.oppia.android.app.model.SchemaObject
 import org.oppia.android.app.model.UserAnswer
 import org.oppia.android.app.model.WrittenTranslationContext
 import org.oppia.android.app.player.state.answerhandling.AnswerErrorCategory
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerErrorOrAvailabilityCheckReceiver
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerReceiver
 import org.oppia.android.app.player.state.itemviewmodel.MathExpressionInteractionsViewModel
 import org.oppia.android.app.player.state.itemviewmodel.NumericInputViewModel
-import org.oppia.android.app.player.state.itemviewmodel.RatioExpressionInputInteractionViewModel
 import org.oppia.android.app.player.state.itemviewmodel.StateItemViewModel
 import org.oppia.android.app.player.state.itemviewmodel.StateItemViewModel.InteractionItemFactory
 import org.oppia.android.app.player.state.itemviewmodel.TextInputViewModel
@@ -53,25 +51,13 @@ class InputInteractionViewTestActivity :
   @Inject
   lateinit var textInputViewModelFactory: TextInputViewModel.FactoryImpl
 
-  @Inject
-  lateinit var ratioViewModelFactory: RatioExpressionInputInteractionViewModel.FactoryImpl
-
   @Inject
   lateinit var mathExpViewModelFactoryFactory: MathExpViewModelFactoryFactoryImpl
 
   val numericInputViewModel by lazy { numericInputViewModelFactory.create<NumericInputViewModel>() }
 
   val textInputViewModel by lazy { textInputViewModelFactory.create<TextInputViewModel>() }
 
-  val ratioExpressionInputInteractionViewModel by lazy {
-    ratioViewModelFactory.create<RatioExpressionInputInteractionViewModel>(
-      interaction = Interaction.newBuilder().putCustomizationArgs(
-        "numberOfTerms",
-        SchemaObject.newBuilder().setSignedInt(3).build()
-      ).build()
-    )
-  }
-
   lateinit var mathExpressionViewModel: MathExpressionInteractionsViewModel
   lateinit var writtenTranslationContext: WrittenTranslationContext
 
@@ -118,14 +104,11 @@ class InputInteractionViewTestActivity :
 
     binding.numericInputViewModel = numericInputViewModel
     binding.textInputViewModel = textInputViewModel
-    binding.ratioInteractionInputViewModel = ratioExpressionInputInteractionViewModel
     binding.mathExpressionInteractionsViewModel = mathExpressionViewModel
   }
 
   fun getPendingAnswerErrorOnSubmitClick(v: View) {
     numericInputViewModel.checkPendingAnswerError(AnswerErrorCategory.SUBMIT_TIME)
-    ratioExpressionInputInteractionViewModel
-      .checkPendingAnswerError(AnswerErrorCategory.SUBMIT_TIME)
   }
 
   override fun onPendingAnswerErrorOrAvailabilityCheck(

app/src/main/java/org/oppia/android/app/testing/RatioInputInteractionViewTestActivity.kt

@@ -0,0 +1,120 @@
+package org.oppia.android.app.testing
+
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import android.view.View
+import androidx.databinding.DataBindingUtil
+import org.oppia.android.R
+import org.oppia.android.app.activity.ActivityComponentImpl
+import org.oppia.android.app.activity.InjectableAutoLocalizedAppCompatActivity
+import org.oppia.android.app.customview.interaction.RatioInputInteractionView
+import org.oppia.android.app.model.InputInteractionViewTestActivityParams
+import org.oppia.android.app.model.Interaction
+import org.oppia.android.app.model.SchemaObject
+import org.oppia.android.app.model.UserAnswer
+import org.oppia.android.app.model.WrittenTranslationContext
+import org.oppia.android.app.player.state.answerhandling.AnswerErrorCategory
+import org.oppia.android.app.player.state.answerhandling.InteractionAnswerErrorOrAvailabilityCheckReceiver
+import org.oppia.android.app.player.state.answerhandling.InteractionAnswerReceiver
+import org.oppia.android.app.player.state.itemviewmodel.RatioExpressionInputInteractionViewModel
+import org.oppia.android.app.player.state.itemviewmodel.StateItemViewModel
+import org.oppia.android.app.player.state.itemviewmodel.StateItemViewModel.InteractionItemFactory
+import org.oppia.android.app.player.state.listener.StateKeyboardButtonListener
+import org.oppia.android.databinding.ActivityRatioInputInteractionViewTestBinding
+import org.oppia.android.util.extensions.getProtoExtra
+import org.oppia.android.util.extensions.putProtoExtra
+import javax.inject.Inject
+
+/**
+ * This is a dummy activity to test [RatioInputInteractionView].
+ */
+class RatioInputInteractionViewTestActivity :
+  InjectableAutoLocalizedAppCompatActivity(),
+  StateKeyboardButtonListener,
+  InteractionAnswerErrorOrAvailabilityCheckReceiver,
+  InteractionAnswerReceiver {
+  private lateinit var binding: ActivityRatioInputInteractionViewTestBinding
+
+  @Inject
+  lateinit var ratioViewModelFactory: RatioExpressionInputInteractionViewModel.FactoryImpl
+
+  /**
+   * Gives access to the [RatioExpressionInputInteractionViewModel].
+   */
+  val ratioExpressionInputInteractionViewModel by lazy {
+    ratioViewModelFactory.create<RatioExpressionInputInteractionViewModel>(
+      interaction = Interaction.newBuilder().putCustomizationArgs(
+        "numberOfTerms",
+        SchemaObject.newBuilder().setSignedInt(3).build()
+      ).build()
+    )
+  }
+
+  /**
+   * Gives access to the translation context.
+   */
+  lateinit var writtenTranslationContext: WrittenTranslationContext
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    (activityComponent as ActivityComponentImpl).inject(this)
+    binding = DataBindingUtil.setContentView<ActivityRatioInputInteractionViewTestBinding>(
+      this, R.layout.activity_ratio_input_interaction_view_test
+    )
+
+    val params =
+      intent.getProtoExtra(
+        TEST_ACTIVITY_PARAMS_ARGUMENT_KEY,
+        InputInteractionViewTestActivityParams.getDefaultInstance()
+      )
+    writtenTranslationContext = params.writtenTranslationContext
+
+    binding.ratioInteractionInputViewModel = ratioExpressionInputInteractionViewModel
+  }
+
+  /**
+   * Checks for submit time errors.
+   */
+  fun getPendingAnswerErrorOnSubmitClick(v: View) {
+    ratioExpressionInputInteractionViewModel
+      .checkPendingAnswerError(AnswerErrorCategory.SUBMIT_TIME)
+  }
+
+  override fun onAnswerReadyForSubmission(answer: UserAnswer) { }
+
+  override fun onEditorAction(actionCode: Int) { }
+
+  private inline fun <reified T : StateItemViewModel> InteractionItemFactory.create(
+    interaction: Interaction = Interaction.getDefaultInstance()
+  ): T {
+    return create(
+      entityId = "fake_entity_id",
+      hasConversationView = false,
+      interaction = interaction,
+      interactionAnswerReceiver = this@RatioInputInteractionViewTestActivity,
+      answerErrorReceiver = this@RatioInputInteractionViewTestActivity,
+      hasPreviousButton = false,
+      isSplitView = false,
+      writtenTranslationContext,
+      timeToStartNoticeAnimationMs = null
+    ) as T
+  }
+
+  companion object {
+    private const val TEST_ACTIVITY_PARAMS_ARGUMENT_KEY =
+      "RatioInputInteractionViewTestActivity.params"
+
+    /**
+     * Creates an intent to open [RatioInputInteractionViewTestActivity].
+     */
+    fun createIntent(
+      context: Context,
+      extras: InputInteractionViewTestActivityParams
+    ): Intent {
+      return Intent(context, RatioInputInteractionViewTestActivity::class.java).also {
+        it.putProtoExtra(TEST_ACTIVITY_PARAMS_ARGUMENT_KEY, extras)
+      }
+    }
+  }
+}

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

@@ -15,10 +15,6 @@
       name="textInputViewModel"
       type="org.oppia.android.app.player.state.itemviewmodel.TextInputViewModel" />
 
-    <variable
-      name="ratioInteractionInputViewModel"
-      type="org.oppia.android.app.player.state.itemviewmodel.RatioExpressionInputInteractionViewModel" />
-
     <variable
       name="mathExpressionInteractionsViewModel"
       type="org.oppia.android.app.player.state.itemviewmodel.MathExpressionInteractionsViewModel" />
@@ -36,43 +32,6 @@
       android:orientation="vertical"
       tools:context=".testing.InputInteractionViewTestActivity">
 
-      <org.oppia.android.app.customview.interaction.RatioInputInteractionView
-        android:id="@+id/test_ratio_input_interaction_view"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:layout_margin="8dp"
-        android:background="@drawable/edit_text_background"
-        android:fontFamily="sans-serif"
-        android:hint="@{ratioInteractionInputViewModel.hintText}"
-        android:imeOptions="actionDone"
-        android:longClickable="false"
-        android:maxLength="200"
-        android:minHeight="48dp"
-        android:paddingStart="16dp"
-        android:paddingEnd="16dp"
-        android:paddingBottom="8dp"
-        android:singleLine="true"
-        android:text="@={ratioInteractionInputViewModel.answerText}"
-        android:textColor="@color/component_color_shared_primary_text_color"
-        android:textColorHint="@color/component_color_shared_edit_text_hint_color"
-        android:textSize="14sp"
-        android:textStyle="italic"
-        app:textChangedListener="@{ratioInteractionInputViewModel.answerTextWatcher}" />
-
-      <TextView
-        android:id="@+id/ratio_input_error"
-        style="@style/TextViewStart"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:layout_marginStart="16dp"
-        android:layout_marginEnd="8dp"
-        android:fontFamily="sans-serif"
-        android:minHeight="32dp"
-        android:text="@{ratioInteractionInputViewModel.errorMessage}"
-        android:textColor="@color/component_color_shared_input_error_color"
-        android:textSize="12sp"
-        android:visibility="@{ratioInteractionInputViewModel.errorMessage.length() > 0 ? View.VISIBLE : View.INVISIBLE}" />
-
       <org.oppia.android.app.customview.interaction.NumericInputInteractionView
         android:id="@+id/test_number_input_interaction_view"
         android:layout_width="match_parent"