fixed tests NextDateTimeTests

Source/MoreDotNet.Test/Extensions/Common/RandomExtensions/NextDateTime.cs

@@ -1,60 +1,56 @@
 namespace MoreDotNet.Tests.Extensions.Common.RandomExtensions
 {
     using System;
+    using System.Collections.Generic;
     using System.Linq;
 
     using MoreDotNet.Extensions.Common;
-
     using Xunit;
 
     public class NextDateTime
     {
         private const int Counter = 1000;
+        private DateTime minDate = new DateTime(1999, 10, 31);
+        private DateTime maxDate = new DateTime(1999, 10, 31);
 
         [Fact]
-        public void NextDateTime_ShouldThrow_ArgumentNullException()
+        public void NextDateTime_RandomIsNull_ShouldThrow_ArgumentNullException()
         {
             Random random = null;
 
             Assert.Throws<ArgumentNullException>(() => random.NextDateTime());
         }
 
-		// TODO: minValue => null / maxValue => null ; 
-
         [Fact]
-        public void NextDateTime_ShouldReturnDateTime()
+        public void NextDateTime_MinValueIsGreaterThanMaxValue_ShouldThrow_ArgumentException()
         {
-            var random = new Random();
-            var result = random.NextDateTime();
+            Random random = new Random();
 
-            Assert.IsType<DateTime>(result);
+            Assert.Throws<ArgumentException>(() => random.NextDateTime(this.maxDate, this.minDate));
         }
 
         [Fact]
-        public void NextDateTime_ShouldReturnDateTime_OneHundredDistinctValues()
+        public void NextDateTime_ShouldReturnDateTime_99PercentOfTimes()
         {
-            // TODO: Fix test
             var random = new Random();
-            var dates = new DateTime[Counter];
+            var dates = new HashSet<DateTime>();
             for (int i = 0; i < Counter; i++)
             {
-                dates[i] = random.NextDateTime();
+                dates.Add(random.NextDateTime());
             }
 
-            Assert.Equal(Counter, dates.Distinct().Count());
+            Assert.True(dates.Count() >= (Counter * 99 / 100));
         }
 
         [Fact]
         public void NextDateTime_ShouldReturnDateTime_BetweenMinAndMaxValue()
         {
             var random = new Random();
-            var mivValue = new DateTime(2016, 1, 1, 0, 0, 0);
-            var maxValue = new DateTime(2018, 1, 1, 0, 0, 0);
             for (int i = 0; i < Counter; i++)
             {
-                var result = random.NextDateTime(mivValue, maxValue);
+                var result = random.NextDateTime(this.minDate, this.maxDate);
 
-                Assert.True(result >= mivValue && result < maxValue);
+                Assert.True(result >= this.minDate && result < this.maxDate);
             }
         }
     }