Generalize ReagentUnit into FixedPoint2 and use it for damage calculations (#5151)

* Damage units

* sum ext method

Content.Tests/Shared/Chemistry/FixedPoint2_Tests.cs

@@ -0,0 +1,145 @@
+using System;
+using Content.Shared.Chemistry;
+using Content.Shared.Chemistry.Reagent;
+using Content.Shared.FixedPoint;
+using NUnit.Framework;
+
+namespace Content.Tests.Shared.Chemistry
+{
+    [TestFixture, TestOf(typeof(FixedPoint2))]
+    public class FixedPoint2_Tests
+    {
+        [Test]
+        [TestCase(1, "1")]
+        [TestCase(0, "0")]
+        [TestCase(-1, "-1")]
+        public void FixedPoint2IntegerTests(int value, string expected)
+        {
+            var result = FixedPoint2.New(value);
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase(1.001f, "1")]
+        [TestCase(0.999f, "1")]
+        public void FixedPoint2FloatTests(float value, string expected)
+        {
+            var result = FixedPoint2.New(value);
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase(1.001d, "1")]
+        [TestCase(0.999d, "1")]
+        public void FixedPoint2DoubleTests(double value, string expected)
+        {
+            var result = FixedPoint2.New(value);
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase("1.005", "1.01")]
+        [TestCase("0.999", "1")]
+        public void FixedPoint2StringTests(string value, string expected)
+        {
+            var result = FixedPoint2.New(value);
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase(1.001f, 1.001f, "2")]
+        [TestCase(1.001f, 1.004f, "2")]
+        [TestCase(1f, 1.005f, "2.01")]
+        [TestCase(1f, 2.005f, "3.01")]
+        public void CalculusPlus(float aFloat, float bFloat, string expected)
+        {
+            var a = FixedPoint2.New(aFloat);
+            var b = FixedPoint2.New(bFloat);
+
+            var result = a + b;
+
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase(1.001f, 1.001f, "0")]
+        [TestCase(1.001f, 1.004f, "0")]
+        [TestCase(1f, 2.005f, "-1.01")]
+        public void CalculusMinus(float aFloat, float bFloat, string expected)
+        {
+            var a = FixedPoint2.New(aFloat);
+            var b = FixedPoint2.New(bFloat);
+
+            var result = a - b;
+
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase(1.001f, 3f, "0.33")]
+        [TestCase(0.999f, 3f, "0.33")]
+        [TestCase(2.1f, 3f, "0.7")]
+        public void CalculusDivision(float aFloat, float bFloat, string expected)
+        {
+            var a = FixedPoint2.New(aFloat);
+            var b = FixedPoint2.New(bFloat);
+
+            var result = a / b;
+
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase(1.001f, 0.999f, "1")]
+        [TestCase(0.999f, 3f, "3")]
+        public void CalculusMultiplication(float aFloat, float bFloat, string expected)
+        {
+            var a = FixedPoint2.New(aFloat);
+            var b = FixedPoint2.New(bFloat);
+
+            var result = a * b;
+
+            Assert.That($"{result}", Is.EqualTo(expected));
+        }
+
+        [Test]
+        [TestCase(0.995f, 100)]
+        [TestCase(1.005f, 101)]
+        [TestCase(2.005f, 201)]
+        public void FloatRoundingTest(float a, int expected)
+        {
+            var result = (int) MathF.Round(a * (float) MathF.Pow(10, 2), MidpointRounding.AwayFromZero);
+            Assert.That(result, Is.EqualTo(expected));
+        }
+
+        [Test]
+        public void FixedPoint2Min()
+        {
+            var unorderedList = new[]
+            {
+                FixedPoint2.New(5),
+                FixedPoint2.New(3),
+                FixedPoint2.New(1),
+                FixedPoint2.New(2),
+                FixedPoint2.New(4),
+            };
+            var min = FixedPoint2.Min(unorderedList);
+            Assert.That(min, Is.EqualTo(FixedPoint2.New(1)));
+        }
+
+        [Test]
+        [TestCase(1, 0, false)]
+        [TestCase(0, 0, true)]
+        [TestCase(-1, 0, false)]
+        [TestCase(1, 1, true)]
+        [TestCase(0, 1, false)]
+        [TestCase(-1, 1, false)]
+        public void FixedPoint2Equals(int a, int b, bool expected)
+        {
+            var parameter = FixedPoint2.New(a);
+            var comparison = FixedPoint2.New(b);
+            Assert.That(parameter.Equals(comparison), Is.EqualTo(comparison.Equals(parameter)));
+            Assert.That(comparison.Equals(parameter), Is.EqualTo(expected));
+        }
+    }
+}