From 9e52256196f52ba58f107556f30cf70fdf5eeb5e Mon Sep 17 00:00:00 2001
From: dovisutu <40313014+dovisutu@users.noreply.github.com>
Date: Fri, 3 Jan 2020 18:21:12 +0800
Subject: [PATCH] Fix prefix 0s after deleting decimal point (#825)

---
 src/CalcManager/CEngine/CalcInput.cpp                |  4 ++++
 src/CalculatorUITests/StandardModeFunctionalTests.cs | 11 +++++++++++
 src/CalculatorUnitTests/CalcInputTest.cpp            | 10 ++++++++++
 3 files changed, 25 insertions(+)

diff --git a/src/CalcManager/CEngine/CalcInput.cpp b/src/CalcManager/CEngine/CalcInput.cpp
index 0de37d5..5bbc140 100644
--- a/src/CalcManager/CEngine/CalcInput.cpp
+++ b/src/CalcManager/CEngine/CalcInput.cpp
@@ -231,6 +231,10 @@ void CalcInput::Backspace()
         if (!m_base.IsEmpty())
         {
             m_base.value.pop_back();
+            if (m_base.value == L"0")
+            {
+                m_base.value.pop_back();
+            }
         }
 
         if (m_base.value.size() <= m_decPtIndex)
diff --git a/src/CalculatorUITests/StandardModeFunctionalTests.cs b/src/CalculatorUITests/StandardModeFunctionalTests.cs
index 2418dff..817f7f3 100644
--- a/src/CalculatorUITests/StandardModeFunctionalTests.cs
+++ b/src/CalculatorUITests/StandardModeFunctionalTests.cs
@@ -184,6 +184,17 @@ public void Operator_Delete()
             Assert.AreEqual("-1,234", page.GetCalculatorResultText());
         }
 
+        // Issue #817: Prefixed multiple zeros
+        [TestMethod]
+        public void Operator_Delete_Prefix_Zeros()
+        {
+            page.StandardOperators.NumberPad.Input(0.1); // To enter decimal point
+            page.StandardOperators.BackSpaceButton.Click();
+            page.StandardOperators.BackSpaceButton.Click();
+            page.StandardOperators.NumberPad.Input(0);
+            Assert.AreEqual("0", page.GetCalculatorResultText());
+        }
+
         [TestMethod]
         public void Operator_ClearAll()
         {
diff --git a/src/CalculatorUnitTests/CalcInputTest.cpp b/src/CalculatorUnitTests/CalcInputTest.cpp
index d5cbaaf..377993e 100644
--- a/src/CalculatorUnitTests/CalcInputTest.cpp
+++ b/src/CalculatorUnitTests/CalcInputTest.cpp
@@ -252,6 +252,16 @@ namespace CalculatorEngineTests
             m_calcInput.Backspace();
             VERIFY_ARE_EQUAL(L"1.2", m_calcInput.ToString(10), L"Verify input after backspace.");
         }
+        // Issue #817: Prefixed multiple zeros
+        TEST_METHOD(BackspaceZeroDecimalWithoutPrefixZeros)
+        {
+            m_calcInput.TryAddDigit(0, 10, false, L"999", 64, 32);
+            m_calcInput.TryAddDecimalPt();
+            VERIFY_ARE_EQUAL(L"0.", m_calcInput.ToString(10), L"Verify input before backspace.")
+            m_calcInput.Backspace();
+            m_calcInput.TryAddDigit(0, 10, false, L"999", 64, 32);
+            VERIFY_ARE_EQUAL(L"0", m_calcInput.ToString(10), L"Verify input after backspace.")
+        }
 
         TEST_METHOD(SetDecimalSymbol)
         {