Adding support for .NET6 DateOnly struct

Src/FluentAssertions/AssertionExtensions.cs

@@ -434,6 +434,30 @@ public static NullableDateTimeOffsetAssertions Should(this DateTimeOffset? actua
             return new NullableDateTimeOffsetAssertions(actualValue);
         }
 
+#if NET6_0_OR_GREATER
+
+        /// <summary>
+        /// Returns an <see cref="DateOnlyAssertions"/> object that can be used to assert the
+        /// current <see cref="DateOnly"/>.
+        /// </summary>
+        [Pure]
+        public static DateOnlyAssertions Should(this DateOnly actualValue)
+        {
+            return new DateOnlyAssertions(actualValue);
+        }
+
+        /// <summary>
+        /// Returns an <see cref="NullableDateOnlyAssertions"/> object that can be used to assert the
+        /// current nullable <see cref="DateOnly"/>.
+        /// </summary>
+        [Pure]
+        public static NullableDateOnlyAssertions Should(this DateOnly? actualValue)
+        {
+            return new NullableDateOnlyAssertions(actualValue);
+        }
+
+#endif
+
         /// <summary>
         /// Returns an <see cref="ComparableTypeAssertions{T}"/> object that can be used to assert the
         /// current <see cref="IComparable{T}"/>.

Src/FluentAssertions/Extensions/FluentDateOnlyExtensions.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Diagnostics;
+
+#if NET6_0_OR_GREATER
+
+namespace FluentAssertions.Extensions
+{
+    /// <summary>
+    /// Extension methods on <see cref="int"/> to allow for a more fluent way of specifying a <see cref="DateOnly"/>.
+    /// </summary>
+    [DebuggerNonUserCode]
+    public static class FluentDateOnlyExtensions
+    {
+        /// <summary>
+        /// Returns a new <see cref="DateOnly"/> value that is <paramref name="dayDifference"/> days before the
+        /// specified <paramref name="sourceDateOnly"/>.
+        /// </summary>
+        public static DateOnly Before(this int dayDifference, DateOnly sourceDateOnly)
+        {
+            return sourceDateOnly.AddDays(-1 * dayDifference);
+        }
+
+        /// <summary>
+        /// Returns a new <see cref="DateOnly"/> value that is <paramref name="dayDifference"/> days after the
+        /// specified <paramref name="sourceDateOnly"/>.
+        /// </summary>
+        public static DateOnly After(this int dayDifference, DateOnly sourceDateOnly)
+        {
+            return sourceDateOnly.AddDays(dayDifference);
+        }
+    }
+}
+
+#endif

Src/FluentAssertions/Formatting/DateOnlyValueFormatter.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Globalization;
+
+#if NET6_0_OR_GREATER
+
+namespace FluentAssertions.Formatting
+{
+    public class DateOnlyValueFormatter : IValueFormatter
+    {
+        /// <summary>
+        /// Indicates whether the current <see cref="IValueFormatter"/> can handle the specified <paramref name="value"/>.
+        /// </summary>
+        /// <param name="value">The value for which to create a <see cref="string"/>.</param>
+        /// <returns>
+        /// <c>true</c> if the current <see cref="IValueFormatter"/> can handle the specified value; otherwise, <c>false</c>.
+        /// </returns>
+        public bool CanHandle(object value)
+        {
+            return value is DateOnly;
+        }
+
+        public void Format(object value, FormattedObjectGraph formattedGraph, FormattingContext context, FormatChild formatChild)
+        {
+            var dateOnly = (DateOnly)value;
+
+            formattedGraph.AddFragment("<");
+            formattedGraph.AddFragment(dateOnly.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture));
+            formattedGraph.AddFragment(">");
+        }
+    }
+}
+
+#endif

Src/FluentAssertions/Formatting/Formatter.cs

@@ -31,6 +31,9 @@ public static class Formatter
             new NullValueFormatter(),
             new GuidValueFormatter(),
             new DateTimeOffsetValueFormatter(),
+#if NET6_0_OR_GREATER
+            new DateOnlyValueFormatter(),
+#endif
             new TimeSpanValueFormatter(),
             new Int32ValueFormatter(),
             new Int64ValueFormatter(),