[andrewabestGH-87] Added convention to enforce a project file sets a property

Some examples:
- Convention.MustSetPropertyValue("Nullable", "enable") // Ensure nullable types are enabled for the project
- Convention.MustSetPropertyValue("IsPackable", "true") // Ensure the project can be packed for NuGet

See https://learn.microsoft.com/en-us/visualstudio/msbuild/property-element-msbuild?view=vs-2022#example

Author: eddie.stanley

src/Core/Conventional.Tests/Conventional/Conventions/Assemblies/AssemblyConventionSpecificationTests.cs

@@ -281,5 +281,60 @@ public void MustNotReferencePackage_Failure()
 
             result.IsSatisfied.Should().BeFalse();
         }
+
+        [Test]
+        public void MustSetPropertyValue_SingleValue_Success()
+        {
+            var result = TheAssembly
+                .WithNameMatching("SdkClassLibrary1")
+                .MustConformTo(Convention.MustSetPropertyValue("TheUniversalAnswer", "42"));
+
+            result.IsSatisfied.Should().BeTrue();
+        }
+
+        [Theory]
+        [TestCase("Potato")]
+        [TestCase("Carrot")]
+        public void MustSetPropertyValue_MultipleValues_Success(string value)
+        {
+            var result = TheAssembly
+                .WithNameMatching("SdkClassLibrary1")
+                .MustConformTo(Convention.MustSetPropertyValue("Vegetable", value));
+
+            result.IsSatisfied.Should().BeTrue();
+        }
+
+        [Test]
+        public void MustSetPropertyValue_SingleValue_Failure()
+        {
+            var result = TheAssembly
+                .WithNameMatching("SdkClassLibrary1")
+                .MustConformTo(Convention.MustSetPropertyValue("TheUniversalAnswer", "41.999"));
+
+            result.IsSatisfied.Should().BeFalse();
+            result.Failures.Single().Should().Be("SdkClassLibrary1 should have property TheUniversalAnswer with value 41.999");
+        }
+
+        [Test]
+        public void MustSetPropertyValue_MultipleValues_Failure()
+        {
+            var result = TheAssembly
+                .WithNameMatching("SdkClassLibrary1")
+                .MustConformTo(Convention.MustSetPropertyValue("Vegetable", "Turnip")); // There's no <Vegetable>Turnip</Vegetable> in the csproj
+
+            result.IsSatisfied.Should().BeFalse();
+            result.Failures.Single().Should().Be("SdkClassLibrary1 should have property Vegetable with value Turnip");
+        }
+
+        [Test]
+        public void MustSetPropertyValue_NoValues_Failure()
+        {
+            var result = TheAssembly
+                .WithNameMatching("SdkClassLibrary1")
+                .MustConformTo(Convention.MustSetPropertyValue("ThisPropertyShouldNeverEverExist", "x")); // There's no <ThisPropertyShouldNeverEverExist>x</ThisPropertyShouldNeverEverExist> in the csproj
+
+            result.IsSatisfied.Should().BeFalse();
+            result.Failures.Single().Should().Be("SdkClassLibrary1 should have property ThisPropertyShouldNeverEverExist with value x");
+        }
     }
 }

src/Core/Conventional/Convention.Assembly.cs

@@ -94,5 +94,17 @@ public static MustNotReferencePackageAssemblyConventionSpecification MustNotRefe
         {
             return new MustNotReferencePackageAssemblyConventionSpecification(packageName);
         }
+
+        /// <summary>
+        /// Require this project to set a <see href="https://learn.microsoft.com/en-us/visualstudio/msbuild/property-element-msbuild?view=vs-2022#example">property value</see>
+        /// </summary>
+        /// <param name="propertyName">The name of the property</param>
+        /// <param name="value">The value the property should have</param>
+        /// <remarks>This convention is currently ignorant of <see href="https://learn.microsoft.com/en-us/visualstudio/msbuild/msbuild-conditions">MSBuild conditions</see></remarks>
+        public static MustSetPropertyValueAssemblyConventionSpecification MustSetPropertyValue(
+            string propertyName, string value)
+        {
+            return new MustSetPropertyValueAssemblyConventionSpecification(propertyName, value);
+        }
     }
 }

src/Core/Conventional/Conventions/Assemblies/MustSetPropertyValueAssemblyConventionSpecification.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Linq;
+using System.Xml.Linq;
+using System.Xml.XPath;
+
+namespace Conventional.Conventions.Assemblies
+{
+    public class MustSetPropertyValueAssemblyConventionSpecification : AssemblyConventionSpecification
+    {
+        private string ExpectedPropertyName { get; }
+        private string ExpectedPropertyValue { get; }
+
+        public MustSetPropertyValueAssemblyConventionSpecification(string expectedPropertyName, string expectedPropertyValue)
+        {
+            ExpectedPropertyName = expectedPropertyName;
+            ExpectedPropertyValue = expectedPropertyValue;
+        }
+
+        protected override ConventionResult IsSatisfiedByLegacyCsprojFormat(string assemblyName, XDocument projectDocument)
+        {
+            return IsSatisfiedBy(assemblyName, projectDocument);
+        }
+
+        protected override ConventionResult IsSatisfiedBy(string assemblyName, XDocument projectDocument)
+        {
+            var matchingProperties = projectDocument.XPathSelectElements($"/Project/PropertyGroup/{ExpectedPropertyName}")
+                .Select(propertyElement => propertyElement.Value)
+                .Where(propertyValue => string.Equals(ExpectedPropertyValue, propertyValue, StringComparison.InvariantCulture));
+
+            return matchingProperties.Count() == 1
+                ? ConventionResult.Satisfied(assemblyName)
+                : ConventionResult.NotSatisfied(assemblyName, string.Format(FailureMessage, assemblyName));
+        }
+
+        protected override string FailureMessage => "{0} should have property " + ExpectedPropertyName + " with value " + ExpectedPropertyValue;
+    }
+}

src/Core/TestSolution/TestSolution.TestProject/SdkClassLibrary1/SdkClassLibrary1.csproj

@@ -1,5 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
+    <PropertyGroup>
+        <TheUniversalAnswer>42</TheUniversalAnswer>
+        <Vegetable>Potato</Vegetable>
+        <Vegetable>Carrot</Vegetable>
+    </PropertyGroup>    
+    
     <PropertyGroup>
         <TargetFramework>netstandard2.1</TargetFramework>
     </PropertyGroup>