From 45a26ac63799a553730f6191ea9d8bdc01bb330d Mon Sep 17 00:00:00 2001
From: iamgabrielma <gabrielmaldonado.art@gmail.com>
Date: Thu, 23 Jan 2025 08:43:16 +0100
Subject: [PATCH 1/2] Validate empty cash user input as zero

---
 .../ViewHelpers/CollectCashViewHelper.swift   |  4 +-
 .../CollectCashViewHelperTests.swift          | 55 +++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift b/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift
index 5c64de135c7..79ca11c6b2e 100644
--- a/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift
+++ b/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift
@@ -36,8 +36,10 @@ final class CollectCashViewHelper {
     func validateAmountOnSubmit(orderTotal: String,
                                 textFieldAmountInput: String,
                                 onError: (String) -> Void) -> Bool {
+        let userInput = textFieldAmountInput.isEmpty ? "0" : textFieldAmountInput
+
         guard let orderDecimal = parseCurrency(orderTotal),
-              let inputDecimal = parseCurrency(textFieldAmountInput) else {
+              let inputDecimal = parseCurrency(userInput) else {
             onError(Localization.failedToCollectCashPayment)
             return false
         }
diff --git a/WooCommerce/WooCommerceTests/POS/ViewModels/CollectCashViewHelperTests.swift b/WooCommerce/WooCommerceTests/POS/ViewModels/CollectCashViewHelperTests.swift
index fa2ecbc2033..a6561bb7e8e 100644
--- a/WooCommerce/WooCommerceTests/POS/ViewModels/CollectCashViewHelperTests.swift
+++ b/WooCommerce/WooCommerceTests/POS/ViewModels/CollectCashViewHelperTests.swift
@@ -207,4 +207,59 @@ struct CollectCashViewHelperTests {
         #expect(result == false)
         #expect(capturedErrorMessage == expectedErrorMessage)
     }
+
+    @Test func validateAmountOnSubmit_when_input_is_empty_then_returns_true() {
+        // Given
+        let orderTotal = "$0.00"
+        let inputAmount = ""
+
+        // When
+        let result = sut.validateAmountOnSubmit(
+            orderTotal: orderTotal,
+            textFieldAmountInput: inputAmount,
+            onError: { _ in })
+
+        // Then
+        #expect(result == true)
+    }
+
+    @Test func validateAmountOnSubmit_when_orderTotal_is_empty_then_returns_false_with_expected_error_message() {
+        // Given
+        let orderTotal = ""
+        let inputAmount = ""
+        let expectedErrorMessage = "Error trying to process payment. Try again."
+        var capturedErrorMessage: String?
+
+        // When
+        let result = sut.validateAmountOnSubmit(
+            orderTotal: orderTotal,
+            textFieldAmountInput: inputAmount,
+            onError: { error in
+                capturedErrorMessage = error
+            })
+
+        // Then
+        #expect(result == false)
+        #expect(capturedErrorMessage == expectedErrorMessage)
+    }
+
+    @Test func validateAmountOnSubmit_when_inputDecimal_is_empty_and_less_than_orderTotal_then_returns_false_with_expected_error_message() {
+        // Given
+        let orderTotal = "$1.00"
+        let inputAmount = ""
+        let expectedErrorMessage = "Amount must be more or equal to total."
+        var capturedErrorMessage: String?
+
+        // When
+        let result = sut.validateAmountOnSubmit(
+            orderTotal: orderTotal,
+            textFieldAmountInput: inputAmount,
+            onError: { error in
+                capturedErrorMessage = error
+            })
+
+        // Then
+        #expect(result == false)
+        #expect(capturedErrorMessage == expectedErrorMessage)
+    }
 }

From 29b3990e37903911b2ba9eae2d428b5fed8bc7e3 Mon Sep 17 00:00:00 2001
From: iamgabrielma <gabrielmaldonado.art@gmail.com>
Date: Thu, 23 Jan 2025 10:13:17 +0100
Subject: [PATCH 2/2] switch logic to handle most common case first

---
 WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift b/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift
index 79ca11c6b2e..a80717b45a1 100644
--- a/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift
+++ b/WooCommerce/Classes/POS/ViewHelpers/CollectCashViewHelper.swift
@@ -36,7 +36,7 @@ final class CollectCashViewHelper {
     func validateAmountOnSubmit(orderTotal: String,
                                 textFieldAmountInput: String,
                                 onError: (String) -> Void) -> Bool {
-        let userInput = textFieldAmountInput.isEmpty ? "0" : textFieldAmountInput
+        let userInput = textFieldAmountInput.isNotEmpty ? textFieldAmountInput : "0"
 
         guard let orderDecimal = parseCurrency(orderTotal),
               let inputDecimal = parseCurrency(userInput) else {