[SL.Core] Remove unused DebugGaurd tests

tests/SixLabors.Core.Tests/Helpers/DebugGuardTests.cs

@@ -5,7 +5,6 @@
 #define DEBUG
 
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Reflection;
@@ -123,42 +122,6 @@ namespace SixLabors.Helpers.Tests
             Assert.True(exception.Message.Contains($"Value must be greater than or equal to 2."));
         }
 
-        [Fact]
-        public void IsTrue_IsTrue_ThrowsNoException()
-        {
-            DebugGuard.IsTrue(true, "myParamName", "myTestMessage");
-        }
-
-        [Fact]
-        public void IsTrue_IsFalse_ThrowsException()
-        {
-            var exception = Assert.Throws<ArgumentException>(() =>
-            {
-                DebugGuard.IsTrue(false, "myParamName", "myTestMessage");
-            });
-
-            Assert.Equal("myParamName", exception.ParamName);
-            Assert.True(exception.Message.Contains("myTestMessage"));
-        }
-
-        [Fact]
-        public void IsFalse_IsFalse_ThrowsNoException()
-        {
-            DebugGuard.IsFalse(false, "myParamName", "myTestMessage");
-        }
-
-        [Fact]
-        public void IsFalse_IsTrue_ThrowsException()
-        {
-            var exception = Assert.Throws<ArgumentException>(() =>
-            {
-                DebugGuard.IsFalse(true, "myParamName", "myTestMessage");
-            });
-
-            Assert.Equal("myParamName", exception.ParamName);
-            Assert.True(exception.Message.Contains("myTestMessage"));
-        }
-
         [Theory]
         [InlineData(new int[] { 1, 2 }, 1)]
         [InlineData(new int[] { 1, 2 }, 2)]