Add string syntax attributes

src/NUnitFramework/framework/Attributes/IgnoreAttribute.cs

@@ -39,6 +39,7 @@ public IgnoreAttribute(string reason)
         /// property set which will appear in the test results.
         /// </remarks>
         /// <exception cref="FormatException">The string does not contain a valid string representation of a date and time.</exception>
+        [StringSyntax(StringSyntaxAttribute.DateTimeFormat)]
         [DisallowNull]
         public string? Until
         {

src/NUnitFramework/framework/Attributes/TestCaseAttribute.cs

@@ -266,6 +266,7 @@ public bool Explicit
         /// <summary>
         /// Gets and sets the ignore until date for this test case.
         /// </summary>
+        [StringSyntax(StringSyntaxAttribute.DateTimeFormat)]
         [DisallowNull]
         public string? Until
         {

src/NUnitFramework/framework/Compatibility/StringSyntaxAttribute.cs

@@ -0,0 +1,76 @@
+// Copyright (c) Charlie Poole, Rob Prouse and Contributors. MIT License - see LICENSE.txt
+
+#if !NET7_0_OR_GREATER
+
+namespace System.Diagnostics.CodeAnalysis
+{
+    /// <summary>Specifies the syntax used in a string.</summary>
+    [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
+    internal sealed class StringSyntaxAttribute : Attribute
+    {
+        /// <summary>The syntax identifier for strings containing composite formats for string formatting.</summary>
+        public const string CompositeFormat = nameof(CompositeFormat);
+
+        /// <summary>The syntax identifier for strings containing date format specifiers.</summary>
+        public const string DateOnlyFormat = nameof(DateOnlyFormat);
+
+        /// <summary>The syntax identifier for strings containing date and time format specifiers.</summary>
+        public const string DateTimeFormat = nameof(DateTimeFormat);
+
+        /// <summary>The syntax identifier for strings containing <see cref="Enum"/> format specifiers.</summary>
+        public const string EnumFormat = nameof(EnumFormat);
+
+        /// <summary>The syntax identifier for strings containing <see cref="Guid"/> format specifiers.</summary>
+        public const string GuidFormat = nameof(GuidFormat);
+
+        /// <summary>The syntax identifier for strings containing JavaScript Object Notation (JSON).</summary>
+        public const string Json = nameof(Json);
+
+        /// <summary>The syntax identifier for strings containing numeric format specifiers.</summary>
+        public const string NumericFormat = nameof(NumericFormat);
+
+        /// <summary>The syntax identifier for strings containing regular expressions.</summary>
+        public const string Regex = nameof(Regex);
+
+        /// <summary>The syntax identifier for strings containing time format specifiers.</summary>
+        public const string TimeOnlyFormat = nameof(TimeOnlyFormat);
+
+        /// <summary>The syntax identifier for strings containing <see cref="TimeSpan"/> format specifiers.</summary>
+        public const string TimeSpanFormat = nameof(TimeSpanFormat);
+
+        /// <summary>The syntax identifier for strings containing URIs.</summary>
+        public const string Uri = nameof(Uri);
+
+        /// <summary>The syntax identifier for strings containing XML.</summary>
+        public const string Xml = nameof(Xml);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StringSyntaxAttribute"/> class with the identifier of the syntax used.
+        /// </summary>
+        /// <param name="syntax">The syntax identifier.</param>
+        public StringSyntaxAttribute(string syntax)
+        {
+            Syntax = syntax;
+            Arguments = Array.Empty<object?>();
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StringSyntaxAttribute"/> class with the identifier of the syntax used.
+        /// </summary>
+        /// <param name="syntax">The syntax identifier.</param>
+        /// <param name="arguments">Optional arguments associated with the specific syntax employed.</param>
+        public StringSyntaxAttribute(string syntax, params object?[] arguments)
+        {
+            Syntax = syntax;
+            Arguments = arguments;
+        }
+
+        /// <summary>Gets the identifier of the syntax used.</summary>
+        public string Syntax { get; }
+
+        /// <summary>Gets optional arguments associated with the specific syntax employed.</summary>
+        public object?[] Arguments { get; }
+    }
+}
+
+#endif

src/NUnitFramework/framework/Constraints/ConstraintExpression.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections;
+using System.Diagnostics.CodeAnalysis;
 using System.Text.RegularExpressions;
 
 namespace NUnit.Framework.Constraints
@@ -768,7 +769,7 @@ public EndsWithConstraint EndsWith(string expected)
         /// Returns a constraint that succeeds if the actual
         /// value matches the regular expression supplied as an argument.
         /// </summary>
-        public RegexConstraint Match(string pattern)
+        public RegexConstraint Match([StringSyntax(StringSyntaxAttribute.Regex)] string pattern)
         {
             return (RegexConstraint)Append(new RegexConstraint(pattern));
         }
@@ -786,7 +787,7 @@ public RegexConstraint Match(Regex regex)
         /// Returns a constraint that succeeds if the actual
         /// value matches the regular expression supplied as an argument.
         /// </summary>
-        public RegexConstraint Matches(string pattern)
+        public RegexConstraint Matches([StringSyntax(StringSyntaxAttribute.Regex)] string pattern)
         {
             return (RegexConstraint)Append(new RegexConstraint(pattern));
         }

src/NUnitFramework/framework/Constraints/RegexConstraint.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Charlie Poole, Rob Prouse and Contributors. MIT License - see LICENSE.txt
 
+using System.Diagnostics.CodeAnalysis;
 using System.Text.RegularExpressions;
 
 namespace NUnit.Framework.Constraints
@@ -34,7 +35,7 @@ public override string Description
         /// Initializes a new instance of the <see cref="RegexConstraint"/> class.
         /// </summary>
         /// <param name="pattern">The pattern.</param>
-        public RegexConstraint(string pattern) : base(pattern)
+        public RegexConstraint([StringSyntax(StringSyntaxAttribute.Regex)] string pattern) : base(pattern)
         {
             _regex = new Regex(pattern);
         }

src/NUnitFramework/framework/Does.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Charlie Poole, Rob Prouse and Contributors. MIT License - see LICENSE.txt
 
+using System.Diagnostics.CodeAnalysis;
 using System.Text.RegularExpressions;
 using NUnit.Framework.Constraints;
 
@@ -109,7 +110,7 @@ public static EndsWithConstraint EndWith(string expected)
         /// Returns a constraint that succeeds if the actual
         /// value matches the regular expression supplied as an argument.
         /// </summary>
-        public static RegexConstraint Match(string pattern)
+        public static RegexConstraint Match([StringSyntax(StringSyntaxAttribute.Regex)] string pattern)
         {
             return new RegexConstraint(pattern);
         }