test: WIP fix testing in ubuntu.

tests/Test.Ursa/DateTimePickerTests/DateRangeTests.cs

@@ -0,0 +1,64 @@
+using Ursa.Controls;
+
+namespace Test.Ursa.DateTimePicker;
+
+public class DateRangeTests
+{
+    [Fact]
+    public void DateRange_SingleDayRange_ShouldHaveSameStartAndEnd()
+    {
+        var date = new DateTime(2023, 10, 1);
+        var range = new DateRange(date);
+
+        Assert.Equal(date.Date, range.Start);
+        Assert.Equal(date.Date, range.End);
+    }
+
+    [Fact]
+    public void DateRange_ValidRange_ShouldSetStartAndEndCorrectly()
+    {
+        var start = new DateTime(2023, 10, 1);
+        var end = new DateTime(2023, 10, 5);
+        var range = new DateRange(start, end);
+
+        Assert.Equal(start.Date, range.Start);
+        Assert.Equal(end.Date, range.End);
+    }
+
+    [Fact]
+    public void DateRange_EndBeforeStart_ShouldSetEndToStart()
+    {
+        var start = new DateTime(2023, 10, 5);
+        var end = new DateTime(2023, 10, 1);
+        var range = new DateRange(start, end);
+
+        Assert.Equal(start.Date, range.Start);
+        Assert.Equal(start.Date, range.End);
+    }
+
+    [Fact]
+    public void Contains_DateWithinRange_ShouldReturnTrue()
+    {
+        var range = new DateRange(new DateTime(2023, 10, 1), new DateTime(2023, 10, 5));
+        var date = new DateTime(2023, 10, 3);
+
+        Assert.True(range.Contains(date));
+    }
+
+    [Fact]
+    public void Contains_DateOutsideRange_ShouldReturnFalse()
+    {
+        var range = new DateRange(new DateTime(2023, 10, 1), new DateTime(2023, 10, 5));
+        var date = new DateTime(2023, 10, 6);
+
+        Assert.False(range.Contains(date));
+    }
+
+    [Fact]
+    public void Contains_NullDate_ShouldReturnFalse()
+    {
+        var range = new DateRange(new DateTime(2023, 10, 1), new DateTime(2023, 10, 5));
+
+        Assert.False(range.Contains(null));
+    }
+}