Update dotnet from 3.0 to 3.1, and pass more 5 tests clock

Author: neiesc

Exercism/csharp/clock/Clock.cs

@@ -12,9 +12,22 @@ public Clock(int hours, int minutes)
             hours = hours + (minutes / 60);
             minutes = minutes % 60;
         }
+        else if (minutes < 0)
+        {
+            hours -= 1;
+        }
 
         _hours = hours % 24;
+        if (_hours < 0)
+        {
+            _hours = 24 - Math.Abs(_hours);
+        }
+
         _minutes = minutes;
+        if (_minutes < 0)
+        {
+            _minutes = 60 - Math.Abs(_minutes);
+        }
     }
 
     public Clock Add(int minutesToAdd)

Exercism/csharp/clock/Clock.csproj

@@ -1,13 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
-  <ItemGroup>
-    <Compile Remove="Example.cs" />
-  </ItemGroup>
-
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.6.1" />
     <PackageReference Include="xunit" Version="2.4.1" />

Exercism/csharp/clock/ClockTests.cs

@@ -74,35 +74,35 @@ public void Hour_and_minutes_roll_over_continuously()
         Assert.Equal("11:01", sut.ToString());
     }
 
-    [Fact(Skip = "Remove this Skip property to run this test")]
+    [Fact]
     public void Hour_and_minutes_roll_over_to_exactly_midnight()
     {
         var sut = new Clock(72, 8640);
         Assert.Equal("00:00", sut.ToString());
     }
 
-    [Fact(Skip = "Remove this Skip property to run this test")]
+    [Fact]
     public void Negative_hour()
     {
         var sut = new Clock(-1, 15);
         Assert.Equal("23:15", sut.ToString());
     }
 
-    [Fact(Skip = "Remove this Skip property to run this test")]
+    [Fact]
     public void Negative_hour_rolls_over()
     {
         var sut = new Clock(-25, 0);
         Assert.Equal("23:00", sut.ToString());
     }
 
-    [Fact(Skip = "Remove this Skip property to run this test")]
+    [Fact]
     public void Negative_hour_rolls_over_continuously()
     {
         var sut = new Clock(-91, 0);
         Assert.Equal("05:00", sut.ToString());
     }
 
-    [Fact(Skip = "Remove this Skip property to run this test")]
+    [Fact]
     public void Negative_minutes()
     {
         var sut = new Clock(1, -40);