Disallow multiple usage

Author: ErikSchierboom

src/Exercism.Tests/TaskAttribute.cs

@@ -2,15 +2,15 @@
 
 namespace Exercism.Tests
 {
-    [AttributeUsage(AttributeTargets.Method, AllowMultiple = true, Inherited = false)]
+    [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
     public class TaskAttribute : Attribute
     {
         public int Number { get; }
 
         public TaskAttribute(int number)
         {
             if (number <= 0) throw new ArgumentOutOfRangeException(nameof(number), number, "Number must be greater than zero");
-            
+
             Number = number;
         }
     }

tests/Exercism.Tests.Tests/TaskAttributeTests.cs

@@ -6,25 +6,18 @@ namespace Exercism.Tests.Tests
     public class TaskAttributeTests
     {
         [Fact]
-        public void AllowsOneDeclaration()
+        public void CanBeUsedOnMethod()
         {
             [Task(1)]
             string TestMethod() => "One";
         }
-        
-        [Fact]
-        public void AllowsMultipleDeclarations()
-        {
-            [Task(1), Task(2), Task(3)]
-            string TestMethod() => "One, Two, Three";
-        }
-        
+
         [Fact]
         public void ThrowsArgumentOutOfRangeExceptionWhenNumberIsZero()
         {
             Assert.Throws<ArgumentOutOfRangeException>(() => new TaskAttribute(0));
         }
-        
+
         [Theory]
         [InlineData(-1)]
         [InlineData(-2)]