Add test generator for grains exercise (#392)

* Add test generator for grains exercise

* Integrate feedback

Author: robkeim

exercises/grains/Example.cs

@@ -1,7 +1,14 @@
-public static class Grains
+using System;
+
+public static class Grains
 {
     public static ulong Square(int n)
     {
+        if (n <= 0 || n > 64)
+        {
+            throw new ArgumentOutOfRangeException(nameof(n));
+        }
+
         return n == 1
             ? 1
             : 2 * Square(n - 1);

exercises/grains/GrainsTest.cs

@@ -1,52 +1,73 @@
-using Xunit;
+// This file was auto-generated based on version 1.0.0 of the canonical data.
+
+using Xunit;
+using System;
 
 public class GrainsTest
 {
     [Fact]
-    public void Test_square_1()
+    public void Returns_the_total_number_of_grains_on_the_board()
+    {
+        Assert.Equal(18446744073709551615UL, Grains.Total());
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Number_1()
+    {
+        Assert.Equal(1UL, Grains.Square(1));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Number_2()
+    {
+        Assert.Equal(2UL, Grains.Square(2));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Number_3()
     {
-        Assert.Equal(1ul, Grains.Square(1));
+        Assert.Equal(4UL, Grains.Square(3));
     }
 
     [Fact(Skip = "Remove to run test")]
-    public void Test_square_2()
+    public void Number_4()
     {
-        Assert.Equal(2ul, Grains.Square(2));
+        Assert.Equal(8UL, Grains.Square(4));
     }
 
     [Fact(Skip = "Remove to run test")]
-    public void Test_square_3()
+    public void Number_16()
     {
-        Assert.Equal(4ul, Grains.Square(3));
+        Assert.Equal(32768UL, Grains.Square(16));
     }
 
     [Fact(Skip = "Remove to run test")]
-    public void Test_square_4()
+    public void Number_32()
     {
-        Assert.Equal(8ul, Grains.Square(4));
+        Assert.Equal(2147483648UL, Grains.Square(32));
     }
 
     [Fact(Skip = "Remove to run test")]
-    public void Test_square_16()
+    public void Number_64()
     {
-        Assert.Equal(32768ul, Grains.Square(16));
+        Assert.Equal(9223372036854775808UL, Grains.Square(64));
     }
 
     [Fact(Skip = "Remove to run test")]
-    public void Test_square_32()
+    public void Square_0_raises_an_exception()
     {
-        Assert.Equal(2147483648ul, Grains.Square(32));
+        Assert.Throws<ArgumentOutOfRangeException>(() => Grains.Square(0));
     }
 
     [Fact(Skip = "Remove to run test")]
-    public void Test_square_64()
+    public void Negative_square_raises_an_exception()
     {
-        Assert.Equal(9223372036854775808ul, Grains.Square(64));
+        Assert.Throws<ArgumentOutOfRangeException>(() => Grains.Square(-1));
     }
 
     [Fact(Skip = "Remove to run test")]
-    public void Test_total_grains()
+    public void Square_greater_than_64_raises_an_exception()
     {
-        Assert.Equal(18446744073709551615ul, Grains.Total());
+        Assert.Throws<ArgumentOutOfRangeException>(() => Grains.Square(65));
     }
 }

generators/Exercises/Grains.cs

@@ -0,0 +1,29 @@
+using System;
+using Generators.Input;
+
+namespace Generators.Exercises
+{
+    public class Grains : Exercise
+    {
+        protected override void UpdateCanonicalData(CanonicalData canonicalData)
+        {
+            foreach (var canonicalDataCase in canonicalData.Cases)
+            {
+                if (ShouldThrowException(canonicalDataCase.Expected))
+                {
+                    canonicalDataCase.ExceptionThrown = typeof(ArgumentOutOfRangeException);
+                }
+                else
+                {
+                    canonicalDataCase.Expected = ulong.Parse(canonicalDataCase.Expected.ToString());
+                }
+            }
+        }
+
+        private static bool ShouldThrowException(object value)
+        {
+            return int.TryParse(value.ToString(), out int result)
+                && result == -1;
+        }
+    }
+}

generators/Output/ValueFormatter.cs

@@ -32,6 +32,8 @@ public static object Format(object val)
                     return dbl.ToString(CultureInfo.InvariantCulture);
                 case float flt:
                     return flt.ToString(CultureInfo.InvariantCulture);
+                case ulong ulng:
+                    return $"{ulng}UL";
                 case char c:
                     return $"'{c}'";
                 default: