Implement payment_method_remove_last for PaymentSheet (#9708)

* Implement `payment_method_remove_last` for `PaymentSheet`

* Add tests for `payment_method_remove_last`

payments-core/detekt-baseline.xml

@@ -34,7 +34,7 @@
     <ID>LongMethod:CardFormViewTest.kt$CardFormViewTest$@Test fun testCardValidCallback()</ID>
     <ID>LongMethod:CardInputWidget.kt$CardInputWidget$private fun initView(attrs: AttributeSet?)</ID>
     <ID>LongMethod:CollectBankAccountViewModel.kt$CollectBankAccountViewModel$private suspend fun createFinancialConnectionsSession()</ID>
-    <ID>LongMethod:ElementsSessionFixtures.kt$ElementsSessionFixtures$fun createPaymentIntentWithCustomerSession( allowRedisplay: String? = "limited" ): JSONObject</ID>
+    <ID>LongMethod:ElementsSessionFixtures.kt$ElementsSessionFixtures$fun createPaymentIntentWithCustomerSession( allowRedisplay: String? = "limited", paymentMethodRemoveFeature: String? = "enabled", paymentMethodRemoveLastFeature: String? = "enabled", ): JSONObject</ID>
     <ID>LongMethod:ElementsSessionJsonParserTest.kt$ElementsSessionJsonParserTest$@Test fun `ElementsSession has expected customer session information in the response`()</ID>
     <ID>LongMethod:GooglePayJsonFactoryTest.kt$GooglePayJsonFactoryTest$@Test fun testCreatePaymentMethodRequestJson()</ID>
     <ID>LongMethod:PaymentAuthConfigTest.kt$PaymentAuthConfigTest$@Test fun testUiCustomizationWrapper()</ID>

payments-core/src/main/java/com/stripe/android/model/ElementsSession.kt

@@ -90,6 +90,7 @@ data class ElementsSession(
                 data class Enabled(
                     val isPaymentMethodSaveEnabled: Boolean,
                     val isPaymentMethodRemoveEnabled: Boolean,
+                    val canRemoveLastPaymentMethod: Boolean,
                     val allowRedisplayOverride: PaymentMethod.AllowRedisplay?
                 ) : MobilePaymentElement
             }

payments-core/src/main/java/com/stripe/android/model/parsers/ElementsSessionJsonParser.kt

@@ -243,6 +243,7 @@ internal class ElementsSessionJsonParser(
 
             val paymentMethodSaveFeature = paymentSheetFeatures.optString(FIELD_PAYMENT_METHOD_SAVE)
             val paymentMethodRemoveFeature = paymentSheetFeatures.optString(FIELD_PAYMENT_METHOD_REMOVE)
+            val paymentMethodRemoveLastFeature = paymentSheetFeatures.optString(FIELD_PAYMENT_METHOD_REMOVE_LAST)
             val allowRedisplayOverrideValue = paymentSheetFeatures
                 .optString(FIELD_PAYMENT_METHOD_ALLOW_REDISPLAY_OVERRIDE)
 
@@ -253,6 +254,7 @@ internal class ElementsSessionJsonParser(
             ElementsSession.Customer.Components.MobilePaymentElement.Enabled(
                 isPaymentMethodSaveEnabled = paymentMethodSaveFeature == VALUE_ENABLED,
                 isPaymentMethodRemoveEnabled = paymentMethodRemoveFeature == VALUE_ENABLED,
+                canRemoveLastPaymentMethod = paymentMethodRemoveLastFeature == VALUE_ENABLED,
                 allowRedisplayOverride = allowRedisplayOverride,
             )
         } else {
@@ -349,6 +351,7 @@ internal class ElementsSessionJsonParser(
         private const val FIELD_PAYMENT_METHOD_REMOVE = "payment_method_remove"
         private const val FIELD_PAYMENT_METHOD_ALLOW_REDISPLAY_OVERRIDE =
             "payment_method_save_allow_redisplay_override"
+        private const val FIELD_PAYMENT_METHOD_REMOVE_LAST = "payment_method_remove_last"
         private const val VALUE_ENABLED = FIELD_ENABLED
         const val FIELD_GOOGLE_PAY_PREFERENCE = "google_pay_preference"
 

payments-core/src/test/java/com/stripe/android/model/ElementsSessionFixtures.kt

@@ -240,7 +240,9 @@ internal object ElementsSessionFixtures {
     )
 
     fun createPaymentIntentWithCustomerSession(
-        allowRedisplay: String? = "limited"
+        allowRedisplay: String? = "limited",
+        paymentMethodRemoveFeature: String? = "enabled",
+        paymentMethodRemoveLastFeature: String? = "enabled",
     ): JSONObject {
         return JSONObject(
             """
@@ -322,8 +324,9 @@ internal object ElementsSessionFixtures {
                     "mobile_payment_element": {
                       "enabled": true,
                       "features": {
-                        "payment_method_remove": "enabled",
+                        "payment_method_remove": ${paymentMethodRemoveFeature ?: "enabled"},
                         "payment_method_save": "disabled",
+                        "payment_method_remove_last": ${paymentMethodRemoveLastFeature ?: "enabled"},
                         "payment_method_save_allow_redisplay_override": ${allowRedisplay?.let { "\"$it\""} ?: "null"}
                       }
                     },

payments-core/src/test/java/com/stripe/android/model/parsers/ElementsSessionJsonParserTest.kt

@@ -541,6 +541,7 @@ class ElementsSessionJsonParserTest {
                         mobilePaymentElement = ElementsSession.Customer.Components.MobilePaymentElement.Enabled(
                             isPaymentMethodSaveEnabled = false,
                             isPaymentMethodRemoveEnabled = true,
+                            canRemoveLastPaymentMethod = true,
                             allowRedisplayOverride = PaymentMethod.AllowRedisplay.LIMITED,
                         ),
                         customerSheet = ElementsSession.Customer.Components.CustomerSheet.Disabled
@@ -611,6 +612,54 @@ class ElementsSessionJsonParserTest {
         )
     }
 
+    @Test
+    fun `when 'payment_method_remove' is 'enabled' for MPE, 'canRemovePaymentMethods' should be true`() {
+        mobilePaymentElementPermissionsTest(
+            paymentMethodRemoveFeatureValue = "enabled",
+            canRemovePaymentMethods = true,
+        )
+    }
+
+    @Test
+    fun `when 'payment_method_remove' is 'disabled' for MPE, 'canRemovePaymentMethods' should be false`() {
+        mobilePaymentElementPermissionsTest(
+            paymentMethodRemoveFeatureValue = "disabled",
+            canRemovePaymentMethods = false,
+        )
+    }
+
+    @Test
+    fun `when 'payment_method_remove' is unknown value for MPE, 'canRemovePaymentMethods' should be false`() {
+        mobilePaymentElementPermissionsTest(
+            paymentMethodRemoveFeatureValue = "something",
+            canRemovePaymentMethods = false,
+        )
+    }
+
+    @Test
+    fun `when 'payment_method_remove_last' is 'enabled' for MPE, 'canRemoveLastPaymentMethod' should be true`() {
+        mobilePaymentElementPermissionsTest(
+            paymentMethodRemoveLastFeatureValue = "enabled",
+            canRemoveLastPaymentMethod = true,
+        )
+    }
+
+    @Test
+    fun `when 'payment_method_remove_last' is 'disabled' for MPE, 'canRemoveLastPaymentMethod' should be false`() {
+        mobilePaymentElementPermissionsTest(
+            paymentMethodRemoveLastFeatureValue = "disabled",
+            canRemoveLastPaymentMethod = false,
+        )
+    }
+
+    @Test
+    fun `when 'payment_method_remove_last' is unknown value for MPE, 'canRemoveLastPaymentMethod' should be false`() {
+        mobilePaymentElementPermissionsTest(
+            paymentMethodRemoveLastFeatureValue = "something",
+            canRemoveLastPaymentMethod = false,
+        )
+    }
+
     @Test
     fun `ElementsSession has expected customer session information with customer sheet component in the response`() {
         val parser = ElementsSessionJsonParser(
@@ -636,7 +685,7 @@ class ElementsSessionJsonParserTest {
                     components = ElementsSession.Customer.Components(
                         mobilePaymentElement = ElementsSession.Customer.Components.MobilePaymentElement.Disabled,
                         customerSheet = ElementsSession.Customer.Components.CustomerSheet.Enabled(
-                            isPaymentMethodRemoveEnabled = true
+                            isPaymentMethodRemoveEnabled = true,
                         ),
                     )
                 ),
@@ -776,4 +825,38 @@ class ElementsSessionJsonParserTest {
 
         assertThat(enabledComponent?.allowRedisplayOverride).isEqualTo(allowRedisplay)
     }
+
+    private fun mobilePaymentElementPermissionsTest(
+        paymentMethodRemoveFeatureValue: String? = "enabled",
+        paymentMethodRemoveLastFeatureValue: String? = "enabled",
+        canRemovePaymentMethods: Boolean = true,
+        canRemoveLastPaymentMethod: Boolean = true,
+    ) {
+        val parser = ElementsSessionJsonParser(
+            ElementsSessionParams.PaymentIntentType(
+                clientSecret = "secret",
+                customerSessionClientSecret = "customer_session_client_secret",
+                externalPaymentMethods = emptyList(),
+            ),
+            isLiveMode = false,
+        )
+
+        val intent = createPaymentIntentWithCustomerSession(
+            paymentMethodRemoveFeature = paymentMethodRemoveFeatureValue,
+            paymentMethodRemoveLastFeature = paymentMethodRemoveLastFeatureValue,
+        )
+
+        val elementsSession = parser.parse(intent)
+
+        val mobilePaymentElementComponent = elementsSession?.customer?.session?.components?.mobilePaymentElement
+
+        assertThat(mobilePaymentElementComponent)
+            .isInstanceOf(ElementsSession.Customer.Components.MobilePaymentElement.Enabled::class.java)
+
+        val enabledComponent = mobilePaymentElementComponent as?
+            ElementsSession.Customer.Components.MobilePaymentElement.Enabled
+
+        assertThat(enabledComponent?.isPaymentMethodRemoveEnabled).isEqualTo(canRemovePaymentMethods)
+        assertThat(enabledComponent?.canRemoveLastPaymentMethod).isEqualTo(canRemoveLastPaymentMethod)
+    }
 }

paymentsheet-example/src/main/java/com/stripe/android/paymentsheet/example/playground/model/PlaygroundCheckoutModel.kt

@@ -38,6 +38,8 @@ class CheckoutRequest private constructor(
     val paymentMethodSaveFeature: FeatureState?,
     @SerialName("customer_session_payment_method_remove")
     val paymentMethodRemoveFeature: FeatureState?,
+    @SerialName("customer_session_payment_method_remove_last")
+    val paymentMethodRemoveLastFeature: FeatureState?,
     @SerialName("customer_session_payment_method_redisplay")
     val paymentMethodRedisplayFeature: FeatureState?,
     @SerialName("customer_session_payment_method_allow_redisplay_filters")
@@ -69,6 +71,7 @@ class CheckoutRequest private constructor(
         private var requireCvcRecollection: Boolean? = null
         private var paymentMethodSaveFeature: FeatureState = FeatureState.Enabled
         private var paymentMethodRemoveFeature: FeatureState = FeatureState.Enabled
+        private var paymentMethodRemoveLastFeature: FeatureState = FeatureState.Enabled
         private var paymentMethodRedisplayFeature: FeatureState = FeatureState.Enabled
         private var paymentMethodRedisplayFilters: List<AllowRedisplayFilter> = listOf(
             AllowRedisplayFilter.Unspecified,
@@ -129,6 +132,10 @@ class CheckoutRequest private constructor(
             this.paymentMethodRemoveFeature = state
         }
 
+        fun paymentMethodRemoveLastFeature(state: FeatureState) {
+            this.paymentMethodRemoveLastFeature = state
+        }
+
         fun paymentMethodRedisplayFeature(state: FeatureState) {
             this.paymentMethodRedisplayFeature = state
         }
@@ -162,6 +169,7 @@ class CheckoutRequest private constructor(
                 customerSessionComponentName = "mobile_payment_element",
                 paymentMethodSaveFeature = paymentMethodSaveFeature,
                 paymentMethodRemoveFeature = paymentMethodRemoveFeature,
+                paymentMethodRemoveLastFeature = paymentMethodRemoveLastFeature,
                 paymentMethodRedisplayFeature = paymentMethodRedisplayFeature,
                 paymentMethodRedisplayFilters = paymentMethodRedisplayFilters,
                 paymentMethodOverrideRedisplay = paymentMethodOverrideRedisplay,

paymentsheet-example/src/main/java/com/stripe/android/paymentsheet/example/playground/settings/CustomerSessionRemoveLastSettingsDefinition.kt

@@ -0,0 +1,25 @@
+package com.stripe.android.paymentsheet.example.playground.settings
+
+import com.stripe.android.paymentsheet.example.playground.model.CheckoutRequest
+import com.stripe.android.paymentsheet.example.playground.model.FeatureState
+
+internal object CustomerSessionRemoveLastSettingsDefinition : BooleanSettingsDefinition(
+    defaultValue = true,
+    displayName = "Customer Session Remove Last Payment Method",
+    key = "customer_session_payment_method_remove"
+) {
+    override fun createOptions(
+        configurationData: PlaygroundConfigurationData
+    ) = listOf(
+        PlaygroundSettingDefinition.Displayable.Option("Enabled", true),
+        PlaygroundSettingDefinition.Displayable.Option("Disabled", false),
+    )
+
+    override fun configure(value: Boolean, checkoutRequestBuilder: CheckoutRequest.Builder) {
+        if (value) {
+            checkoutRequestBuilder.paymentMethodRemoveLastFeature(FeatureState.Enabled)
+        } else {
+            checkoutRequestBuilder.paymentMethodRemoveLastFeature(FeatureState.Disabled)
+        }
+    }
+}

paymentsheet-example/src/main/java/com/stripe/android/paymentsheet/example/playground/settings/PlaygroundSettings.kt

@@ -418,6 +418,7 @@ internal class PlaygroundSettings private constructor(
             CustomerSessionSettingsDefinition,
             CustomerSessionSaveSettingsDefinition,
             CustomerSessionRemoveSettingsDefinition,
+            CustomerSessionRemoveLastSettingsDefinition,
             CustomerSessionRedisplaySettingsDefinition,
             CustomerSessionRedisplayFiltersSettingsDefinition,
             CustomerSessionOverrideRedisplaySettingsDefinition,

paymentsheet/src/main/java/com/stripe/android/paymentsheet/SavedPaymentMethodMutator.kt

@@ -34,7 +34,6 @@ internal class SavedPaymentMethodMutator(
     private val coroutineScope: CoroutineScope,
     private val workContext: CoroutineContext,
     private val customerRepository: CustomerRepository,
-    private val allowsRemovalOfLastSavedPaymentMethod: Boolean,
     private val selection: StateFlow<PaymentSelection?>,
     val providePaymentMethodName: (PaymentMethodCode?) -> ResolvableString,
     private val clearSelection: () -> Unit,
@@ -62,10 +61,11 @@ internal class SavedPaymentMethodMutator(
     val canRemove: StateFlow<Boolean> = customerStateHolder.customer.mapAsStateFlow { customerState ->
         customerState?.run {
             val hasRemovePermissions = customerState.permissions.canRemovePaymentMethods
+            val hasRemoveLastPaymentMethodPermissions = customerState.permissions.canRemoveLastPaymentMethod
 
             when (paymentMethods.size) {
                 0 -> false
-                1 -> allowsRemovalOfLastSavedPaymentMethod && hasRemovePermissions
+                1 -> hasRemoveLastPaymentMethodPermissions && hasRemovePermissions
                 else -> hasRemovePermissions
             }
         } ?: false
@@ -390,7 +390,6 @@ internal class SavedPaymentMethodMutator(
                 coroutineScope = viewModel.viewModelScope,
                 workContext = viewModel.workContext,
                 customerRepository = viewModel.customerRepository,
-                allowsRemovalOfLastSavedPaymentMethod = viewModel.config.allowsRemovalOfLastSavedPaymentMethod,
                 selection = viewModel.selection,
                 providePaymentMethodName = { code ->
                     code?.let {

paymentsheet/src/main/java/com/stripe/android/paymentsheet/state/CustomerState.kt

@@ -1,6 +1,7 @@
 package com.stripe.android.paymentsheet.state
 
 import android.os.Parcelable
+import com.stripe.android.common.model.CommonConfiguration
 import com.stripe.android.model.ElementsSession
 import com.stripe.android.model.PaymentMethod
 import com.stripe.android.paymentsheet.PaymentSheet
@@ -16,6 +17,7 @@ internal data class CustomerState(
     @Parcelize
     data class Permissions(
         val canRemovePaymentMethods: Boolean,
+        val canRemoveLastPaymentMethod: Boolean,
         val canRemoveDuplicates: Boolean,
     ) : Parcelable
 
@@ -28,17 +30,26 @@ internal data class CustomerState(
          * @return [CustomerState] instance using [ElementsSession.Customer] data
          */
         internal fun createForCustomerSession(
+            configuration: CommonConfiguration,
             customer: ElementsSession.Customer,
             supportedSavedPaymentMethodTypes: List<PaymentMethod.Type>,
         ): CustomerState {
-            val canRemovePaymentMethods = when (
-                val mobilePaymentElementComponent = customer.session.components.mobilePaymentElement
-            ) {
-                is ElementsSession.Customer.Components.MobilePaymentElement.Enabled ->
+            val mobilePaymentElementComponent = customer.session.components.mobilePaymentElement
+
+            val canRemovePaymentMethods = when (mobilePaymentElementComponent) {
+                is ElementsSession.Customer.Components.MobilePaymentElement.Enabled -> {
                     mobilePaymentElementComponent.isPaymentMethodRemoveEnabled
+                }
                 is ElementsSession.Customer.Components.MobilePaymentElement.Disabled -> false
             }
 
+            val canRemoveLastPaymentMethod = when {
+                !configuration.allowsRemovalOfLastSavedPaymentMethod -> false
+                mobilePaymentElementComponent is ElementsSession.Customer.Components.MobilePaymentElement.Enabled ->
+                    mobilePaymentElementComponent.canRemoveLastPaymentMethod
+                else -> false
+            }
+
             return CustomerState(
                 id = customer.session.customerId,
                 ephemeralKeySecret = customer.session.apiKey,
@@ -47,6 +58,7 @@ internal data class CustomerState(
                 },
                 permissions = Permissions(
                     canRemovePaymentMethods = canRemovePaymentMethods,
+                    canRemoveLastPaymentMethod = canRemoveLastPaymentMethod,
                     // Should always remove duplicates when using `customer_session`
                     canRemoveDuplicates = true,
                 )
@@ -63,6 +75,7 @@ internal data class CustomerState(
          * @return [CustomerState] instance with legacy ephemeral key secrets
          */
         internal fun createForLegacyEphemeralKey(
+            configuration: CommonConfiguration,
             customerId: String,
             accessType: PaymentSheet.CustomerAccessType.LegacyCustomerEphemeralKey,
             paymentMethods: List<PaymentMethod>,
@@ -77,6 +90,13 @@ internal data class CustomerState(
                      * always be set to true.
                      */
                     canRemovePaymentMethods = true,
+                    /*
+                     * Un-scoped legacy ephemeral keys normally have full permissions to remove the last payment
+                     * method, however we do have client-side configuration option to configure this ability. This
+                     * should eventually be removed in favor of the server-side option available with customer
+                     * sessions.
+                     */
+                    canRemoveLastPaymentMethod = configuration.allowsRemovalOfLastSavedPaymentMethod,
                     /*
                      * Removing duplicates is not applicable here since we don't filter out duplicates for for
                      * un-scoped ephemeral keys.

paymentsheet/src/main/java/com/stripe/android/paymentsheet/state/PaymentElementLoader.kt

@@ -189,6 +189,7 @@ internal class DefaultPaymentElementLoader @Inject constructor(
                 customerInfo = customerInfo,
                 metadata = metadata.await(),
                 savedSelection = savedSelection,
+                configuration = configuration,
                 cardBrandFilter = PaymentSheetCardBrandFilter(configuration.cardBrandAcceptance)
             )
         }
@@ -313,6 +314,7 @@ internal class DefaultPaymentElementLoader @Inject constructor(
     }
 
     private suspend fun createCustomerState(
+        configuration: CommonConfiguration,
         customerInfo: CustomerInfo?,
         metadata: PaymentMethodMetadata,
         savedSelection: Deferred<SavedSelection>,
@@ -322,13 +324,15 @@ internal class DefaultPaymentElementLoader @Inject constructor(
             is CustomerInfo.CustomerSession -> {
                 CustomerState.createForCustomerSession(
                     customer = customerInfo.elementsSessionCustomer,
+                    configuration = configuration,
                     supportedSavedPaymentMethodTypes = metadata.supportedSavedPaymentMethodTypes()
                 )
             }
             is CustomerInfo.Legacy -> {
                 CustomerState.createForLegacyEphemeralKey(
                     customerId = customerInfo.id,
                     accessType = customerInfo.accessType,
+                    configuration = configuration,
                     paymentMethods = retrieveCustomerPaymentMethods(
                         metadata = metadata,
                         customerConfig = customerInfo.customerConfig,