Added Guid validator

Author: jamesmcroft

src/MADE.Data.Validation/Strings/Resources.Designer.cs

@@ -132,6 +132,9 @@
   <data name="EmailValidator_FeedbackMessage" xml:space="preserve">
     <value>The value must be a valid email address, e.g. test@example.com.</value>
   </data>
+  <data name="GuidValidator_FeedbackMessage" xml:space="preserve">
+    <value>The value must be a valid GUID.</value>
+  </data>
   <data name="IpAddressValidator_FeedbackMessage" xml:space="preserve">
     <value>The value must be a valid IP address, e.g. 192.168.0.1.</value>
   </data>

src/MADE.Data.Validation/Strings/Resources.resx

@@ -0,0 +1,65 @@
+// MADE Apps licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace MADE.Data.Validation.Validators
+{
+    using System;
+    using MADE.Data.Validation.Extensions;
+    using MADE.Data.Validation.Strings;
+
+    /// <summary>
+    /// Defines a data validator for ensuring a value is a <see cref="Guid"/>.
+    /// </summary>
+    public class GuidValidator : IValidator
+    {
+        private string feedbackMessage;
+
+        /// <summary>
+        /// Gets or sets the key associated with the validator.
+        /// </summary>
+        public string Key { get; set; } = nameof(GuidValidator);
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the data provided is in an invalid state.
+        /// </summary>
+        public bool IsInvalid { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the data is dirty.
+        /// </summary>
+        public bool IsDirty { get; set; }
+
+        /// <summary>
+        /// Gets or sets the feedback message to display when <see cref="IValidator.IsInvalid"/> is true.
+        /// </summary>
+        public string FeedbackMessage
+        {
+            get => this.feedbackMessage.IsNullOrWhiteSpace()
+                ? Resources.GuidValidator_FeedbackMessage
+                : this.feedbackMessage;
+            set => this.feedbackMessage = value;
+        }
+
+        /// <summary>
+        /// Executes data validation on the provided <paramref name="value"/>.
+        /// </summary>
+        /// <param name="value">The value to be validated.</param>
+        public void Validate(object value)
+        {
+            bool isInvalid;
+
+            if (value is Guid)
+            {
+                isInvalid = false;
+            }
+            else
+            {
+                var stringValue = value.ToString();
+                isInvalid = !Guid.TryParse(stringValue, out _);
+            }
+
+            this.IsInvalid = isInvalid;
+            this.IsDirty = true;
+        }
+    }
+}

src/MADE.Data.Validation/Validators/GuidValidator.cs

@@ -0,0 +1,72 @@
+namespace MADE.Data.Validation.Tests.Tests
+{
+    using System;
+    using System.Diagnostics.CodeAnalysis;
+    using MADE.Data.Validation.Validators;
+    using NUnit.Framework;
+    using Shouldly;
+
+    [ExcludeFromCodeCoverage]
+    [TestFixture]
+    public class GuidValidatorTests
+    {
+        public class WhenValidating
+        {
+            [Test]
+            public void ShouldBeDirtyOnceValidated()
+            {
+                // Arrange
+                string value = "Test";
+                var validator = new GuidValidator();
+
+                // Act
+                validator.Validate(value);
+
+                // Assert
+                validator.IsDirty.ShouldBe(true);
+            }
+
+            [Test]
+            public void ShouldBeValidIfGuidType()
+            {
+                // Arrange
+                var value = Guid.NewGuid();
+                var validator = new GuidValidator();
+
+                // Act
+                validator.Validate(value);
+
+                // Assert
+                validator.IsInvalid.ShouldBe(false);
+            }
+
+            [Test]
+            public void ShouldBeValidIfStringGuid()
+            {
+                // Arrange
+                var value = "f39bc65d-dcb5-47f1-a3ba-51fb5f584fd9";
+                var validator = new GuidValidator();
+
+                // Act
+                validator.Validate(value);
+
+                // Assert
+                validator.IsInvalid.ShouldBe(false);
+            }
+
+            [Test]
+            public void ShouldBeInvalidIfNotGuid()
+            {
+                // Arrange
+                const string value = "Test";
+                var validator = new GuidValidator();
+
+                // Act
+                validator.Validate(value);
+
+                // Assert
+                validator.IsInvalid.ShouldBe(true);
+            }
+        }
+    }
+}