Add Cpf Validator and its Unit Tests

README.md

@@ -27,6 +27,7 @@ We already have some validators that you can use:
  - CreditCardNumberValidator
  - EmailValidator
  - DateValidator
+ - CpfValidator - (Brazilian Social Security Number)
 
 But feel free to implement yours or contribute with more validators 😉
 

src/Inquirer/Validators/CpfValidator.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Text.RegularExpressions;
+
+namespace InquirerCore.Validators
+{
+    public class CpfValidator : IValidator
+    {
+        public bool Validate(string value)
+        {
+			if (string.IsNullOrEmpty(value))
+				return false;
+
+            // Remove spaces, dashes and dots
+            var cleanCpfNumber = new Regex(@"[\s-.]+")
+                .Replace(value, "");
+
+            // Is all digits with length equals 11?
+            var isValidNumberFormat = new Regex(@"^[0-9]{11}$")
+                .Match(cleanCpfNumber).Success;
+
+            if (isValidNumberFormat)
+                return isValidCpfNumber(cleanCpfNumber);
+
+			return false;
+        }
+
+        private bool isValidCpfNumber(string value)
+        {
+			int[] multplier1 = new int[9] { 10, 9, 8, 7, 6, 5, 4, 3, 2 };
+			int[] multiplier2 = new int[10] { 11, 10, 9, 8, 7, 6, 5, 4, 3, 2 };
+			string tempCpf;
+			string digit;
+			int sum;
+			int rest;
+			tempCpf = value.Substring(0, 9);
+			sum = 0;
+
+			for (int i = 0; i < 9; i++)
+				sum += int.Parse(tempCpf[i].ToString()) * multplier1[i];
+
+			rest = sum % 11;
+
+			if (rest < 2)
+				rest = 0;
+			else
+				rest = 11 - rest;
+
+			digit = rest.ToString();
+			tempCpf = tempCpf + digit;
+			sum = 0;
+
+			for (int i = 0; i < 10; i++)
+				sum += int.Parse(tempCpf[i].ToString()) * multiplier2[i];
+
+			rest = sum % 11;
+
+			if (rest < 2)
+				rest = 0;
+			else
+				rest = 11 - rest;
+
+			digit = digit + rest.ToString();
+
+			return value.EndsWith(digit);
+		}
+
+        public string GetErrorMessage()
+        {
+			return "Answer accepts only CPF's numbers.";
+		}
+
+
+    }
+}

test/InquirerUnitTest/Validators/CpfValidatorUnitTest.cs

@@ -0,0 +1,49 @@
+using FluentAssertions;
+using InquirerCore.Validators;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Xunit;
+
+namespace InquirerUnitTest.Validators
+{
+    public class CpfValidatorUnitTest
+    {
+        [Theory]
+        [InlineData("088.218.720-17")]
+        [InlineData("229.709.540-60")]
+        [InlineData("22970954060")]
+        public void ShouldAcceptCpfValues(string aDateValue)
+        {
+            var validator = new CpfValidator();
+
+            var isValid = validator.Validate(aDateValue);
+
+            isValid.Should().BeTrue();
+        }
+
+        [Theory]
+        [InlineData("22970954060aa")]
+        [InlineData("22970954061")]
+        [InlineData("229709540/60")]
+        [InlineData("invalid")]
+        [InlineData("")]
+        [InlineData(null)]
+        public void ShouldNotAcceptNoCpfValues(string aNonDateValue)
+        {
+            var validator = new CpfValidator();
+
+            var isValid = validator.Validate(aNonDateValue);
+
+            isValid.Should().BeFalse();
+        }
+
+        [Fact]
+        public void ShouldReturnErrorMessage()
+        {
+            var validator = new CpfValidator();
+
+            validator.GetErrorMessage().Should().Be("Answer accepts only CPF's numbers.");
+        }
+    }
+}