Add newBuilder to CustomerSheet.Configuration (#7058)

Author: jameswoo-stripe

paymentsheet-example/src/main/java/com/stripe/android/paymentsheet/example/samples/ui/customersheet/playground/CustomerSheetPlaygroundViewModel.kt

@@ -57,16 +57,8 @@ class CustomerSheetPlaygroundViewModel(
         .googlePayEnabled(viewState.value.isGooglePayEnabled)
         .build()
     val configuration: StateFlow<CustomerSheet.Configuration> = viewState.map {
-        CustomerSheet.Configuration.Builder()
-            .defaultBillingDetails(
-                PaymentSheet.BillingDetails(
-                    name = "CustomerSheet Testing"
-                )
-            ).billingDetailsCollectionConfiguration(
-                PaymentSheet.BillingDetailsCollectionConfiguration(
-                    name = PaymentSheet.BillingDetailsCollectionConfiguration.CollectionMode.Always
-                )
-            )
+        initialConfiguration
+            .newBuilder()
             .googlePayEnabled(it.isGooglePayEnabled)
             .build()
     }.stateIn(viewModelScope, SharingStarted.WhileSubscribed(), initialConfiguration)

paymentsheet/src/main/java/com/stripe/android/customersheet/CustomerSheet.kt

@@ -153,6 +153,17 @@ class CustomerSheet @Inject internal constructor(
          */
         val merchantDisplayName: String? = null,
     ) {
+
+        fun newBuilder(): Builder {
+            return Builder()
+                .appearance(appearance)
+                .googlePayEnabled(googlePayEnabled)
+                .headerTextForSelectionScreen(headerTextForSelectionScreen)
+                .defaultBillingDetails(defaultBillingDetails)
+                .billingDetailsCollectionConfiguration(billingDetailsCollectionConfiguration)
+                .merchantDisplayName(merchantDisplayName)
+        }
+
         @ExperimentalCustomerSheetApi
         @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
         class Builder {

paymentsheet/src/test/java/com/stripe/android/customersheet/CustomerSheetConfigurationTest.kt

@@ -0,0 +1,97 @@
+package com.stripe.android.customersheet
+
+import com.google.common.truth.Truth.assertThat
+import com.stripe.android.paymentsheet.PaymentSheet
+import junit.framework.TestCase.fail
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+@RunWith(RobolectricTestRunner::class)
+@OptIn(ExperimentalCustomerSheetApi::class)
+class CustomerSheetConfigurationTest {
+    @Test
+    fun `Builder returns a configuration`() {
+        val googlePayEnabled = true
+        val merchantDisplayName = "Test"
+        val appearance = PaymentSheet.Appearance().copy(
+            typography = PaymentSheet.Typography.default
+        )
+        val billingDetailsCollectionConfiguration = PaymentSheet.BillingDetailsCollectionConfiguration(
+            name = PaymentSheet.BillingDetailsCollectionConfiguration.CollectionMode.Always
+        )
+        val defaultBillingDetails = PaymentSheet.BillingDetails(
+            name = "Test"
+        )
+        val headerTextForSelectionScreen = "Test"
+
+        val configuration = CustomerSheet.Configuration.Builder()
+            .googlePayEnabled(googlePayEnabled)
+            .merchantDisplayName(merchantDisplayName)
+            .appearance(appearance)
+            .billingDetailsCollectionConfiguration(billingDetailsCollectionConfiguration)
+            .defaultBillingDetails(defaultBillingDetails)
+            .headerTextForSelectionScreen(headerTextForSelectionScreen)
+            .build()
+
+        assertThat(configuration.googlePayEnabled)
+            .isEqualTo(googlePayEnabled)
+        assertThat(configuration.merchantDisplayName)
+            .isEqualTo(merchantDisplayName)
+        assertThat(configuration.appearance)
+            .isEqualTo(appearance)
+        assertThat(configuration.billingDetailsCollectionConfiguration)
+            .isEqualTo(billingDetailsCollectionConfiguration)
+        assertThat(configuration.defaultBillingDetails)
+            .isEqualTo(defaultBillingDetails)
+        assertThat(configuration.headerTextForSelectionScreen)
+            .isEqualTo(headerTextForSelectionScreen)
+    }
+
+    @Test
+    fun `newBuilder returns a new builder with previous configuration`() {
+        val configuration = CustomerSheet.Configuration.Builder()
+            .googlePayEnabled(true)
+            .build()
+
+        val configuration1 = configuration.newBuilder()
+            .build()
+
+        assertThat(configuration1.googlePayEnabled)
+            .isTrue()
+
+        val configuration2 = configuration.newBuilder()
+            .googlePayEnabled(false)
+            .build()
+
+        assertThat(configuration2.googlePayEnabled)
+            .isFalse()
+    }
+
+    @Test
+    fun `Builder has the right methods`() {
+        val knownBuilderMethodNames = setOf(
+            "googlePayEnabled",
+            "merchantDisplayName",
+            "appearance",
+            "billingDetailsCollectionConfiguration",
+            "defaultBillingDetails",
+            "headerTextForSelectionScreen",
+            "build"
+        )
+
+        // Programmatically check for any new method on the builder using reflection
+        val configurationMethods = CustomerSheet.Configuration.Builder::class.java.declaredMethods
+        val newMethods = configurationMethods.map { it.name } - knownBuilderMethodNames
+
+        // If there are any new methods, fail the test
+        if (newMethods.isNotEmpty()) {
+            fail(
+                """
+                New method added to the Builder class: ${newMethods.joinToString()}, please update
+                this test and update CustomerSheet.Configuration#newBuilder
+                """.trimIndent()
+            )
+        }
+    }
+}