add tests

ErsatzTV.Core.Tests/Scheduling/CountExpressionTests.cs

@@ -0,0 +1,34 @@
+using ErsatzTV.Core.Interfaces.Scheduling;
+using ErsatzTV.Core.Scheduling;
+using NSubstitute;
+using NUnit.Framework;
+using Shouldly;
+
+namespace ErsatzTV.Core.Tests.Scheduling;
+
+[TestFixture]
+public class CountExpressionTests
+{
+    [Test]
+    [TestCase("2", 2)]
+    [TestCase("count", 10)]
+    [TestCase("count / 2", 5)]
+    [TestCase("count * 2", 20)]
+    [TestCase("count + 1", 11)]
+    [TestCase("count - 1", 9)]
+    [TestCase("random % 4 + 1", 3)]
+    [TestCase("invalid", 0)]
+    [TestCase("count / 0", 0)]
+    public void Should_Evaluate_Expression(string expression, int expected)
+    {
+        var enumerator = Substitute.For<IMediaCollectionEnumerator>();
+        enumerator.Count.Returns(10);
+
+        var random = Substitute.For<Random>();
+        random.Next().Returns(2);
+
+        int result = CountExpression.Evaluate(expression, enumerator, random, CancellationToken.None);
+
+        result.ShouldBe(expected);
+    }
+}

ErsatzTV.Core/Scheduling/CountExpression.cs

@@ -25,11 +25,22 @@ public static class CountExpression
             };
         };
 
-        object expressionResult = expression.Evaluate(cancellationToken);
+        object expressionResult = 0;
+        try
+        {
+            expressionResult = expression.Evaluate(cancellationToken);
+        }
+        catch (Exception)
+        {
+            // do nothing
+        }
+
         return expressionResult switch
         {
+            double d when double.IsInfinity(d) || double.IsNaN(d) => 0,
             double doubleResult => (int)Math.Floor(doubleResult),
             int intResult => intResult,
+            long longResult => (int)longResult,
             _ => 0
         };
     }

ErsatzTV/Pages/ScheduleItemsEditor.razor

@@ -532,7 +532,8 @@
         </div>
         <MudTextField @bind-Value="@_selectedItem.MultipleCount"
                       For="@(() => _selectedItem.MultipleCount)"
-                      Disabled="@(_selectedItem.PlayoutMode is not PlayoutMode.Multiple || _selectedItem.MultipleMode is not MultipleMode.Count)"/>
+                      Disabled="@(_selectedItem.PlayoutMode is not PlayoutMode.Multiple || _selectedItem.MultipleMode is not MultipleMode.Count)"
+                      HelperText="Can be an expression with 'count' (collection size) and 'random' (0 to count-1)"/>
     </MudStack>
     <MudStack Row="true" Breakpoint="Breakpoint.SmAndDown" Class="form-field-stack gap-md-8 mb-5">
         <div class="d-flex">