Add min length validation to BECS account number (#2293)

- Add validation for BECS account number min length
- Update account number min length based on BSB prefix

stripe/res/values/strings.xml

@@ -159,6 +159,8 @@
     <string name="becs_widget_bsb_incomplete" tools:ignore="MissingTranslation">The BSB you entered is incomplete.</string>
     <!-- BECS Debit Widget - account number field - required error message -->
     <string name="becs_widget_account_number_required" tools:ignore="MissingTranslation">Your account number is required.</string>
+    <!-- BECS Debit Widget - account number field - incomplete error message -->
+    <string name="becs_widget_account_number_incomplete" tools:ignore="MissingTranslation">Your account number is incomplete.</string>
     <!-- BECS Debit Widget - name field - required error message -->
     <string name="becs_widget_name_required" tools:ignore="MissingTranslation">Your name is required.</string>
     <!-- BECS Debit Widget - email address field - required error message -->

stripe/src/main/java/com/stripe/android/view/BecsDebitAccountNumberEditText.kt

@@ -5,13 +5,32 @@ import android.text.Editable
 import android.text.InputFilter
 import android.text.method.DigitsKeyListener
 import android.util.AttributeSet
+import com.stripe.android.R
 
 internal class BecsDebitAccountNumberEditText @JvmOverloads constructor(
     context: Context,
     attrs: AttributeSet? = null,
     defStyleAttr: Int = androidx.appcompat.R.attr.editTextStyle
 ) : StripeEditText(context, attrs, defStyleAttr) {
 
+    val accountNumber: String?
+        get() {
+            errorMessage = when {
+                fieldText.isBlank() -> {
+                    resources.getString(R.string.becs_widget_account_number_required)
+                }
+                fieldText.length < minLength -> {
+                    resources.getString(R.string.becs_widget_account_number_incomplete)
+                }
+                else -> {
+                    null
+                }
+            }
+            return fieldText.takeIf { errorMessage == null }
+        }
+
+    var minLength: Int = DEFAULT_MIN_LENGTH
+
     init {
         filters = arrayOf(InputFilter.LengthFilter(MAX_LENGTH))
         keyListener = DigitsKeyListener.getInstance(false, true)
@@ -23,7 +42,8 @@ internal class BecsDebitAccountNumberEditText @JvmOverloads constructor(
         })
     }
 
-    private companion object {
+    internal companion object {
+        internal const val DEFAULT_MIN_LENGTH = 5
         private const val MAX_LENGTH = 9
     }
 }

stripe/src/main/java/com/stripe/android/view/BecsDebitWidget.kt

@@ -44,6 +44,30 @@ class BecsDebitWidget @JvmOverloads constructor(
                 viewBinding.bsbTextInputLayout.helperText = null
                 viewBinding.bsbTextInputLayout.isHelperTextEnabled = false
             }
+
+            viewBinding.accountNumberEditText.minLength = when (bank?.prefix?.take(2)) {
+                // Stripe
+                "00" -> 9
+
+                // ANZ: 9 digits https://www.anz.com.au/support/help/
+                "01" -> 9
+
+                // NAB: 9 digits
+                // https://www.nab.com.au/business/accounts/business-accounts-online-application-help
+                "08" -> 9
+
+                // Commonwealth/CBA: 8 digits
+                // https://www.commbank.com.au/support.digital-banking.confirm-account-number-digits.html
+                "06" -> 8
+
+                // Westpac/WBC: 6 digits
+                "03", "73" -> 6
+
+                // Cuscal: 4 digits(?)
+                "80" -> 4
+
+                else -> BecsDebitAccountNumberEditText.DEFAULT_MIN_LENGTH
+            }
         }
 
         viewBinding.bsbEditText.onCompletedCallback = {
@@ -79,9 +103,6 @@ class BecsDebitWidget @JvmOverloads constructor(
             ErrorListener(viewBinding.bsbTextInputLayout)
         )
 
-        viewBinding.accountNumberEditText.errorMessage = resources.getString(
-            R.string.becs_widget_account_number_required
-        )
         viewBinding.accountNumberEditText.setErrorMessageListener(
             ErrorListener(viewBinding.accountNumberTextInputLayout)
         )
@@ -104,15 +125,15 @@ class BecsDebitWidget @JvmOverloads constructor(
             val name = viewBinding.nameEditText.fieldText
             val email = viewBinding.emailEditText.fieldText
             val bsbNumber = viewBinding.bsbEditText.bsb
-            val accountNumber = viewBinding.accountNumberEditText.fieldText
+            val accountNumber = viewBinding.accountNumberEditText.accountNumber
 
             viewBinding.nameEditText.shouldShowError = name.isBlank()
             viewBinding.emailEditText.shouldShowError = email.isBlank()
             viewBinding.bsbEditText.shouldShowError = bsbNumber.isNullOrBlank()
-            viewBinding.accountNumberEditText.shouldShowError = accountNumber.isBlank()
+            viewBinding.accountNumberEditText.shouldShowError = accountNumber.isNullOrBlank()
 
             if (name.isBlank() || email.isBlank() || bsbNumber.isNullOrBlank() ||
-                accountNumber.isBlank()) {
+                accountNumber.isNullOrBlank()) {
                 return null
             }
 

stripe/src/test/java/com/stripe/android/view/BecsDebitAccountNumberEditTextTest.kt

@@ -0,0 +1,43 @@
+package com.stripe.android.view
+
+import androidx.test.core.app.ApplicationProvider
+import com.google.common.truth.Truth.assertThat
+import kotlin.test.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+@RunWith(RobolectricTestRunner::class)
+class BecsDebitAccountNumberEditTextTest {
+    private val accountNumberEditText = BecsDebitAccountNumberEditText(
+        ApplicationProvider.getApplicationContext()
+    )
+
+    @Test
+    fun accountNumber_whenEmpty_shouldReturnCorrectErrorMessage() {
+        accountNumberEditText.setText("")
+        assertThat(accountNumberEditText.accountNumber)
+            .isNull()
+        assertThat(accountNumberEditText.errorMessage)
+            .isEqualTo("Your account number is required.")
+    }
+
+    @Test
+    fun accountNumber_whenIncomplete_shouldReturnCorrectErrorMessage() {
+        accountNumberEditText.minLength = 9
+        accountNumberEditText.setText("1234")
+        assertThat(accountNumberEditText.accountNumber)
+            .isNull()
+        assertThat(accountNumberEditText.errorMessage)
+            .isEqualTo("Your account number is incomplete.")
+    }
+
+    @Test
+    fun accountNumber_whenComplete_shouldNotHaveErrorMessage() {
+        accountNumberEditText.minLength = 5
+        accountNumberEditText.setText("123456")
+        assertThat(accountNumberEditText.accountNumber)
+            .isEqualTo("123456")
+        assertThat(accountNumberEditText.errorMessage)
+            .isNull()
+    }
+}

stripe/src/test/java/com/stripe/android/view/BecsDebitWidgetTest.kt

@@ -29,7 +29,7 @@ internal class BecsDebitWidgetTest : BaseViewTest<BecsDebitWidgetTestActivity>(
     private val bsbEditText: BecsDebitBsbEditText by lazy {
         becsDebitWidget.viewBinding.bsbEditText
     }
-    private val accountNumberEditText: StripeEditText by lazy {
+    private val accountNumberEditText: BecsDebitAccountNumberEditText by lazy {
         becsDebitWidget.viewBinding.accountNumberEditText
     }
 
@@ -95,6 +95,23 @@ internal class BecsDebitWidgetTest : BaseViewTest<BecsDebitWidgetTestActivity>(
             )
     }
 
+    @Test
+    fun bsbChange_shouldUpdateAccountNumberEditTextMinLength() {
+        // default
+        assertThat(accountNumberEditText.minLength)
+            .isEqualTo(5)
+
+        // Stripe BSB
+        bsbEditText.setText("00")
+        assertThat(accountNumberEditText.minLength)
+            .isEqualTo(9)
+
+        // Stripe BSB
+        bsbEditText.setText("80")
+        assertThat(accountNumberEditText.minLength)
+            .isEqualTo(4)
+    }
+
     private companion object {
         private const val VALID_BSB_NUMBER = "000000"
         private const val VALID_ACCOUNT_NUMBER = "000123456"