Add Length validator (#44)

src/Immediate.Validations.Shared/Validators/LengthAttribute.cs

@@ -0,0 +1,35 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace Immediate.Validations.Shared;
+
+/// <summary>
+///	    Applied to a <see cref="string"/> property to indicate that the value should have a length of exactly <paramref
+///     name="length"/>.
+/// </summary>
+/// <param name="length">
+///	    The maximum length of the <see cref="string"/>.
+/// </param>
+public sealed class LengthAttribute(
+	[TargetType]
+	object length
+) : ValidatorAttribute
+{
+	/// <summary>
+	///	    Validates that the <see cref="string"/> has a length of exactly <paramref name="length"/>.
+	/// </summary>
+	/// <param name="target">
+	///	    The value to validate.
+	/// </param>
+	/// <param name="length">
+	///		The valid length for the string <paramref name="target"/>.
+	/// </param>
+	/// <returns>
+	///	    A <see cref="ValueTuple{T1, T2}"/> indicating whether the property is valid or not, along with an error
+	///     message if the property is not valid.
+	/// </returns>
+	[SuppressMessage("Design", "CA1062:Validate arguments of public methods", Justification = "Will already by validated by IV first.")]
+	public static (bool Invalid, string? Message) ValidateProperty(string target, int length) =>
+		target.Length == length
+			? default
+			: (true, $"String is of length '{target.Length}', which is {(target.Length < length ? "shorter" : "longer")} than the allowed length of '{length}'.");
+}

src/Immediate.Validations.Shared/Validators/MatchAttribute.cs

@@ -20,15 +20,6 @@ public sealed class MatchAttribute(
 	object? regex = null
 ) : ValidatorAttribute
 {
-	/// <summary>
-	/// 
-	/// </summary>
-	public object? Expr { get; } = expr;
-	/// <summary>
-	/// 
-	/// </summary>
-	public object? Regex { get; } = regex;
-
 	/// <summary>
 	///	    Validates that the <see cref="string"/> matches a particular <see cref="Regex"/> pattern.
 	/// </summary>

src/Immediate.Validations.Shared/Validators/MaxLengthAttribute.cs

@@ -15,13 +15,13 @@ object length
 ) : ValidatorAttribute
 {
 	/// <summary>
-	///	    Validates that the <see cref="string"/> is less than <paramref name="length"/>.
+	///	    Validates that the value should have a length at most <paramref name="length"/>.
 	/// </summary>
 	/// <param name="target">
 	///	    The value to validate.
 	/// </param>
 	/// <param name="length">
-	///		The maximum valid length for the string <paramref name="target"/>.
+	///	    The maximum valid length for the string <paramref name="target"/>.
 	/// </param>
 	/// <returns>
 	///	    A <see cref="ValueTuple{T1, T2}"/> indicating whether the property is valid or not, along with an error

src/Immediate.Validations.Shared/Validators/MinLengthAttribute.cs

@@ -16,13 +16,13 @@ object length
 {
 
 	/// <summary>
-	///	    Validates that the <see cref="string"/> is less than <paramref name="length"/>.
+	///	    Validates that the value should have a length at least <paramref name="length"/>.
 	/// </summary>
 	/// <param name="target">
 	///	    The value to validate.
 	/// </param>
 	/// <param name="length">
-	///		The minimum valid length for the string <paramref name="target"/>.
+	///	    The minimum valid length for the string <paramref name="target"/>.
 	/// </param>
 	/// <returns>
 	///	    A <see cref="ValueTuple{T1, T2}"/> indicating whether the property is valid or not, along with an error

tests/Immediate.Validations.FunctionalTests/Validators/LengthTests.cs

@@ -0,0 +1,62 @@
+using Immediate.Validations.Shared;
+using Xunit;
+
+namespace Immediate.Validations.FunctionalTests.Validators;
+
+public sealed partial class LengthTests
+{
+	[Validate]
+	public partial record StringRecord : IValidationTarget<StringRecord>
+	{
+		[Length(12)]
+		public required string StringValue { get; init; }
+	}
+
+	[Fact]
+	public void LengthWhenShort()
+	{
+		var instance = new StringRecord { StringValue = "Hello" };
+
+		var errors = StringRecord.Validate(instance);
+
+		Assert.Equal(
+			[
+				new()
+				{
+					PropertyName = nameof(StringRecord.StringValue),
+					ErrorMessage = "String is of length '5', which is shorter than the allowed length of '12'.",
+				}
+			],
+			errors
+		);
+	}
+
+	[Fact]
+	public void LengthWhenEqual()
+	{
+		var instance = new StringRecord { StringValue = "Hello World!" };
+
+		var errors = StringRecord.Validate(instance);
+
+		Assert.Empty(errors);
+	}
+
+	[Fact]
+	public void LengthWhenLong()
+	{
+		var instance = new StringRecord { StringValue = "Hello World! Hello World! Hello World!" };
+
+		var errors = StringRecord.Validate(instance);
+
+		Assert.Equal(
+			[
+				new()
+				{
+					PropertyName = nameof(StringRecord.StringValue),
+					ErrorMessage = "String is of length '38', which is longer than the allowed length of '12'.",
+				}
+			],
+			errors
+		);
+	}
+}