Add MathF equality tests

tests/ImageSharp.Tests/Helpers/MathFTests.cs

@@ -0,0 +1,69 @@
+namespace ImageSharp.Tests.Helpers
+{
+    using System;
+
+    using Xunit;
+
+    public class MathFTests
+    {
+        [Fact]
+        public void MathF_PI_Is_Equal()
+        {
+            Assert.Equal(MathF.PI, (float)Math.PI);
+        }
+
+        [Fact]
+        public void MathF_Ceililng_Is_Equal()
+        {
+            Assert.Equal(MathF.Ceiling(0.3333F), (float)Math.Ceiling(0.3333F));
+        }
+
+        [Fact]
+        public void MathF_Abs_Is_Equal()
+        {
+            Assert.Equal(MathF.Abs(-0.3333F), (float)Math.Abs(-0.3333F));
+        }
+
+        [Fact]
+        public void MathF_Exp_Is_Equal()
+        {
+            Assert.Equal(MathF.Exp(1.2345F), (float)Math.Exp(1.2345F));
+        }
+
+        [Fact]
+        public void MathF_Floor_Is_Equal()
+        {
+            Assert.Equal(MathF.Floor(1.2345F), (float)Math.Floor(1.2345F));
+        }
+
+        [Fact]
+        public void MathF_Min_Is_Equal()
+        {
+            Assert.Equal(MathF.Min(1.2345F, 5.4321F), (float)Math.Min(1.2345F, 5.4321F));
+        }
+
+        [Fact]
+        public void MathF_Max_Is_Equal()
+        {
+            Assert.Equal(MathF.Max(1.2345F, 5.4321F), (float)Math.Max(1.2345F, 5.4321F));
+        }
+
+        [Fact]
+        public void MathF_Pow_Is_Equal()
+        {
+            Assert.Equal(MathF.Pow(1.2345F, 5.4321F), (float)Math.Pow(1.2345F, 5.4321F));
+        }
+
+        [Fact]
+        public void MathF_Sin_Is_Equal()
+        {
+            Assert.Equal(MathF.Sin(1.2345F), (float)Math.Sin(1.2345F));
+        }
+
+        [Fact]
+        public void MathF_Sqrt_Is_Equal()
+        {
+            Assert.Equal(MathF.Sqrt(2F), (float)Math.Sqrt(2F));
+        }
+    }
+}