Prevent user to create an order with zero amount

Author: Ecarrion

WooCommerce/Classes/ViewRelated/Orders/Simple Payments/Amount/SimplePaymentsAmountViewModel.swift

@@ -35,11 +35,11 @@ final class SimplePaymentsAmountViewModel: ObservableObject {
     ///
     var onOrderCreated: (Order) -> Void = { _ in }
 
-    /// Returns true when amount has less than two characters.
-    /// Less than two, because `$` should be the first character.
+    /// Returns true when amount is a valid number bigger than .zero.
     ///
     var shouldDisableDoneButton: Bool {
-        amount.count < 2
+        let decimalAmount = (currencyFormatter.convertToDecimal(from: amount) ?? .zero) as Decimal
+        return decimalAmount <= .zero
     }
 
     /// Defines if the view actions should be disabled.
@@ -85,6 +85,10 @@ final class SimplePaymentsAmountViewModel: ObservableObject {
     ///
     private let storeCurrencySettings: CurrencySettings
 
+    /// Currency formatter for the provided amount
+    ///
+    private let currencyFormatter: CurrencyFormatter
+
     /// Current store currency symbol
     ///
     private let storeCurrencySymbol: String
@@ -110,6 +114,7 @@ final class SimplePaymentsAmountViewModel: ObservableObject {
         self.presentNoticeSubject = presentNoticeSubject
         self.storeCurrencySettings = storeCurrencySettings
         self.storeCurrencySymbol = storeCurrencySettings.symbol(from: storeCurrencySettings.currencyCode)
+        self.currencyFormatter = CurrencyFormatter(currencySettings: storeCurrencySettings)
         self.analytics = analytics
         self.isDevelopmentPrototype = isDevelopmentPrototype
     }

WooCommerce/WooCommerceTests/ViewRelated/Orders/Simple Payments/SimplePaymentsAmountViewModelTests.swift

@@ -91,6 +91,17 @@ final class SimplePaymentsAmountViewModelTests: XCTestCase {
         XCTAssertTrue(viewModel.shouldDisableDoneButton)
     }
 
+    func test_view_model_disables_next_button_when_amount_is_not_greater_than_zero() {
+        // Given
+        let viewModel = SimplePaymentsAmountViewModel(siteID: sampleSiteID, storeCurrencySettings: usStoreSettings)
+
+        // When
+        viewModel.amount = "$0"
+
+        // Then
+        XCTAssertTrue(viewModel.shouldDisableDoneButton)
+    }
+
     func test_view_model_enables_next_button_when_amount_has_more_than_one_character() {
         // Given
         let viewModel = SimplePaymentsAmountViewModel(siteID: sampleSiteID, storeCurrencySettings: usStoreSettings)