From 3f78299a1222ea1e7f436c3585a1835da03511b1 Mon Sep 17 00:00:00 2001
From: Dmitriy Barbul <dimabarbul@gmail.com>
Date: Tue, 9 Feb 2016 14:53:25 +0200
Subject: [PATCH] Add throwing exception if variable is not decimal or boolean

---
 Calculator.Core.Tests/CalculatorTest.cs       | 40 +++++++++++++++++++
 Calculator.Core/Calculator.cs                 | 13 ++++--
 .../Enum/CalculateExceptionCode.cs            |  1 +
 Calculator.Core/FormulaTokenizer.cs           |  5 +++
 4 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/Calculator.Core.Tests/CalculatorTest.cs b/Calculator.Core.Tests/CalculatorTest.cs
index 1db824b..1e7fc71 100644
--- a/Calculator.Core.Tests/CalculatorTest.cs
+++ b/Calculator.Core.Tests/CalculatorTest.cs
@@ -255,5 +255,45 @@ public void Calculate_UndefinedVariable_ThrowsException()
         {
             Calculator.Calculate("a");
         }
+
+        [TestMethod]
+        [ExpectedExceptionWithCode(typeof(CalculateException), (int)CalculateExceptionCode.StringVariable)]
+        public void Calculate_StringVariable_ThrowsException()
+        {
+            Calculator.Calculate(
+                "a + c",
+                new Dictionary<string, object>()
+                {
+                    { "a", 1 },
+                    { "c", "test" }
+                }
+            );
+        }
+
+        [TestMethod]
+        [ExpectedExceptionWithCode(typeof(CalculateException), (int)CalculateExceptionCode.StringVariable)]
+        public void Calculate_OperationVariable_ThrowsException()
+        {
+            Calculator.Calculate(
+                "c / 0",
+                new Dictionary<string, object>()
+                {
+                    { "c", "-" }
+                }
+            );
+        }
+
+        [TestMethod]
+        [ExpectedExceptionWithCode(typeof(CalculateException), (int)CalculateExceptionCode.StringVariable)]
+        public void Calculate_SubformulaVariable_ThrowsException()
+        {
+            Calculator.Calculate(
+                "v",
+                new Dictionary<string, object>()
+                {
+                    { "v", "(1+2)" }
+                }
+            );
+        }
     }
 }
diff --git a/Calculator.Core/Calculator.cs b/Calculator.Core/Calculator.cs
index 5fb2a32..5afcf9e 100644
--- a/Calculator.Core/Calculator.cs
+++ b/Calculator.Core/Calculator.cs
@@ -40,10 +40,15 @@ public static TResult Calculate<TResult>(string formula, Dictionary<string, obje
                             throw new CalculateException(CalculateExceptionCode.UnknownVariable);
                         }
 
-                        operands.Push(new Token(
-                            variables[token.Text].ToString(),
-                            FormulaTokenizer.DetectTokenType(variables[token.Text])
-                        ));
+                        TokenType variableType = FormulaTokenizer.DetectTokenType(variables[token.Text]);
+                        if (!FormulaTokenizer.IsValueTokenType(variableType))
+                        {
+                            throw new CalculateException(CalculateExceptionCode.StringVariable);
+                        }
+
+                        Token variableToken = new Token(variables[token.Text].ToString(), variableType);
+
+                        operands.Push(variableToken);
                         break;
                     default:
                         OperationBase operation = OperationFactory.Create(token, operands.Count == 0);
diff --git a/Calculator.Core/Enum/CalculateExceptionCode.cs b/Calculator.Core/Enum/CalculateExceptionCode.cs
index ca617b8..881165f 100644
--- a/Calculator.Core/Enum/CalculateExceptionCode.cs
+++ b/Calculator.Core/Enum/CalculateExceptionCode.cs
@@ -6,5 +6,6 @@ internal enum CalculateExceptionCode
         NotSingleResult = 2,
         MissingOperand = 3,
         UnknownVariable = 4,
+        StringVariable = 5,
     }
 }
diff --git a/Calculator.Core/FormulaTokenizer.cs b/Calculator.Core/FormulaTokenizer.cs
index a3085d2..7b4d98a 100644
--- a/Calculator.Core/FormulaTokenizer.cs
+++ b/Calculator.Core/FormulaTokenizer.cs
@@ -78,5 +78,10 @@ public static TokenType DetectTokenType(object value)
 
             return token.Type;
         }
+
+        public static bool IsValueTokenType(TokenType type)
+        {
+            return type == TokenType.Bool || type == TokenType.Decimal;
+        }
     }
 }