Implement isbn-verifier exercise

config.json

@@ -622,6 +622,19 @@
       "unlocked_by": "accumulate",
       "uuid": "d5d48857-5325-45d2-9969-95a0d7bba370"
     },
+    {
+      "core": false,
+      "difficulty": 4,
+      "slug": "isbn-verifier",
+      "topics": [
+        "conditionals",
+        "loops",
+        "pattern_matching",
+        "strings"
+      ],
+      "unlocked_by": "bob",
+      "uuid": "d714b1e6-48b5-44d6-9661-d0acd3dd657b"
+    },
     {
       "core": false,
       "difficulty": 5,

exercises/Exercises.sln

@@ -220,6 +220,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "CollatzConjecture", "collat
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ComplexNumbers", "complex-numbers\ComplexNumbers.csproj", "{D0399EAC-5563-4234-9828-0C607BAF7623}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "IsbnVerifier", "isbn-verifier\IsbnVerifier.csproj", "{72432190-8D4D-4E64-B622-F83BE80A3CBB}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -662,6 +664,10 @@ Global
 		{D0399EAC-5563-4234-9828-0C607BAF7623}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{D0399EAC-5563-4234-9828-0C607BAF7623}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{D0399EAC-5563-4234-9828-0C607BAF7623}.Release|Any CPU.Build.0 = Release|Any CPU
+		{72432190-8D4D-4E64-B622-F83BE80A3CBB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{72432190-8D4D-4E64-B622-F83BE80A3CBB}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{72432190-8D4D-4E64-B622-F83BE80A3CBB}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{72432190-8D4D-4E64-B622-F83BE80A3CBB}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

exercises/isbn-verifier/Example.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Text.RegularExpressions;
+
+public static class IsbnVerifier
+{
+    public static bool IsValid(string number)
+    {
+        number = number.Replace("-", "");
+
+        if (!Regex.IsMatch(number, @"^(\d{9}[\dX])$"))
+        {
+            return false;
+        }
+
+        var sum = 0;
+        var weight = 10;
+        var digit = 0;
+        for (int i = 0; i < number.Length; i++)
+        {
+            digit = (number[i] == 'X' && i == 9) ? 10 : (int)Char.GetNumericValue(number[i]);
+
+            sum += digit * weight;
+            weight--;
+        }
+        return sum % 11 == 0;
+    }
+}

exercises/isbn-verifier/IsbnVerifier.cs

@@ -0,0 +1,9 @@
+using System;
+
+public static class IsbnVerifier
+{
+    public static bool IsValid(string number)
+    {
+        throw new NotImplementedException("You need to implement this function.");
+    }
+}

exercises/isbn-verifier/IsbnVerifier.csproj

@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Remove="Example.cs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.3.0" />
+    <PackageReference Include="xunit" Version="2.3.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
+  </ItemGroup>
+
+</Project>
+

exercises/isbn-verifier/IsbnVerifierTest.cs

@@ -0,0 +1,84 @@
+// This file was auto-generated based on version 1.1.0 of the canonical data.
+
+using Xunit;
+
+public class IsbnVerifierTest
+{
+    [Fact]
+    public void Valid_isbn_number()
+    {
+        Assert.True(IsbnVerifier.IsValid("3-598-21508-8"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Invalid_isbn_check_digit()
+    {
+        Assert.False(IsbnVerifier.IsValid("3-598-21508-9"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Valid_isbn_number_with_a_check_digit_of_10()
+    {
+        Assert.True(IsbnVerifier.IsValid("3-598-21507-X"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Check_digit_is_a_character_other_than_x()
+    {
+        Assert.False(IsbnVerifier.IsValid("3-598-21507-A"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Invalid_character_in_isbn()
+    {
+        Assert.False(IsbnVerifier.IsValid("3-598-2K507-0"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void X_is_only_valid_as_a_check_digit()
+    {
+        Assert.False(IsbnVerifier.IsValid("3-598-2X507-9"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Valid_isbn_without_separating_dashes()
+    {
+        Assert.True(IsbnVerifier.IsValid("3598215088"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Isbn_without_separating_dashes_and_x_as_check_digit()
+    {
+        Assert.True(IsbnVerifier.IsValid("359821507X"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Isbn_without_check_digit_and_dashes()
+    {
+        Assert.False(IsbnVerifier.IsValid("359821507"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Too_long_isbn_and_no_dashes()
+    {
+        Assert.False(IsbnVerifier.IsValid("3598215078X"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Isbn_without_check_digit()
+    {
+        Assert.False(IsbnVerifier.IsValid("3-598-21507"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Too_long_isbn()
+    {
+        Assert.False(IsbnVerifier.IsValid("3-598-21507-XX"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Check_digit_of_x_should_not_be_used_for_0()
+    {
+        Assert.False(IsbnVerifier.IsValid("3-598-21515-X"));
+    }
+}

exercises/isbn-verifier/README.md

@@ -0,0 +1,40 @@
+# ISBN Verifier
+
+Check if a given ISBN-10 is valid.
+
+## Functionality
+
+Given an unknown string the program should check if the provided string is a valid ISBN-10.
+Putting this into place requires some thinking about preprocessing/parsing of the string prior to calculating the check digit for the ISBN.
+
+The program should allow for ISBN-10 without the separating dashes to be verified as well.
+
+## ISBN
+
+Let's take a random ISBN-10 number, say `3-598-21508-8` for this.
+The first digit block indicates the group where the ISBN belongs. Groups can consist of shared languages, geographic regions or countries. The leading '3' signals this ISBN is from a german speaking country.
+The following number block is to identify the publisher. Since this is a three digit publisher number there is a 5 digit title number for this book.
+The last digit in the ISBN is the check digit which is used to detect read errors.
+
+The first 9 digits in the ISBN have to be between 0 and 9.
+The check digit can additionally be an 'X' to allow 10 to be a valid check digit as well.
+
+A valid ISBN-10 is calculated with this formula `(x1 * 10 + x2 * 9 + x3 * 8 + x4 * 7 + x5 * 6 + x6 * 5 + x7 * 4 + x8 * 3 + x9 * 2 + x10 * 1) mod 11 == 0`
+So for our example ISBN this means:
+(3 * 10 + 5 * 9 + 9 * 8 + 8 * 7 + 2 * 6 + 1 * 5 + 5 * 4 + 0 * 3 + 8 * 2 + 8 * 1) mod 11 = 0
+
+Which proves that the ISBN is valid.
+
+### Submitting Exercises
+
+Note that, when trying to submit an exercise, make sure the exercise file that you're submitting is in the `exercism/csharp/<exerciseName>` directory.
+
+For example, if you're submitting `bob.cs` for the Bob exercise, the submit command would be something like `exercism submit <path_to_exercism_dir>/csharp/bob/bob.cs`.
+
+## Source
+
+Wikipedia [https://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digit_calculation](https://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digit_calculation)
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

generators/Exercises/IsbnVerifier.cs

@@ -0,0 +1,15 @@
+using Generators.Input;
+
+namespace Generators.Exercises
+{
+    public class IsbnVerifier : Exercise
+    {
+        protected override void UpdateCanonicalData(CanonicalData canonicalData)
+        {
+            foreach (var canonicalDataCase in canonicalData.Cases)
+            {
+                canonicalDataCase.Property = "IsValid";
+            }
+        }
+    }
+}