From 7c0d009b46057050172b63e4f3713610a6361d24 Mon Sep 17 00:00:00 2001
From: David Prince <david-in-perth@fake.invalid>
Date: Fri, 27 Dec 2013 20:27:42 +0800
Subject: [PATCH] ValidateMean unit test for Categorical dist

Unit tests to validate Categorical.Mean. Currently they fail, indicating
that Categorical.Mean is not correctly implemented.
Unit tests for StdDev, Variance, Entropy, and Median properties are
still required.
---
 .../Discrete/CategoricalTests.cs                 | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/UnitTests/DistributionTests/Discrete/CategoricalTests.cs b/src/UnitTests/DistributionTests/Discrete/CategoricalTests.cs
index 34cb76b1..67d2e9e4 100644
--- a/src/UnitTests/DistributionTests/Discrete/CategoricalTests.cs
+++ b/src/UnitTests/DistributionTests/Discrete/CategoricalTests.cs
@@ -155,6 +155,22 @@ namespace MathNet.Numerics.UnitTests.DistributionTests.Discrete
             Assert.Throws<ArgumentOutOfRangeException>(() => b.P = _badP);
         }
 
+        /// <summary>
+        /// Validate mean.
+        /// </summary>
+        /// <param name="p">An array of nonnegative ratios.</param>
+        /// <param name="mean">Expected value.</param>
+        [TestCase(new double[] { 0, 0.25, 0.5, 0.25 }, 2)]
+        [TestCase(new double[] { 0, 1, 2, 1 }, 2)]
+        [TestCase(new double[] { 0, 0.5, 0.5 }, 1.5)]
+        [TestCase(new double[] { 0.75, 0.25 }, 0.25)]
+        [TestCase(new double[] { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 }, 5)]
+        public void ValidateMean(double[] p, double mean)
+        {
+            var n = new Categorical(p);
+            AssertHelpers.AlmostEqual(mean, n.Mean, 14);
+        }
+
         /// <summary>
         /// Can sample static.
         /// </summary>