Add IsNotEmpty checks for collection (#30)

(MINOR)

.github/workflows/ci.yml

@@ -16,6 +16,7 @@ env:
     DOTNET_VERSION: '8.0.x'
 
 permissions:
+  checks: write
   contents: read
 
 jobs:
@@ -45,19 +46,20 @@ jobs:
       run: dotnet build -c Release -p:Version=${{ steps.version.outputs.version}}
 
     - name: Run tests
-      run: dotnet test tests/MGR.Guard.UnitTests/MGR.Guard.UnitTests.csproj -c Release --no-build --collect:"XPlat Code Coverage" --settings coverlet.runsettings
+      run: dotnet test tests/MGR.Guard.UnitTests/MGR.Guard.UnitTests.csproj -c Release --no-build
 
     - name: Upload dotnet test results
-      uses: actions/upload-artifact@v4
+      uses: dorny/[email protected]
+      if: always()
       with:
-        name: dotnet-results
-        path: '**/coverage.cobertura.xml'
-        if-no-files-found: warn
-      # Use always() to always run this step to publish test results when there are test failures
-      if: ${{ always() }}
-
+        name: .NET Tests
+        path: '**/MGR.Guard.UnitTests.trx'
+        reporter: dotnet-trx
+        fail-on-error: true
+
     - name: Push to MyGet
       env:
         NUGET_URL: https://www.myget.org/F/mgrosperrin/api/v3/index.json
         NUGET_API_KEY: ${{ secrets.MYGET_CI_API_KEY }}
       run: dotnet nuget push '**/*.nupkg' --source "$($env:NUGET_URL)" --api-key "$($env:NUGET_API_KEY)"
+      if: github.event_name == 'push'

docs/guard.md

@@ -70,6 +70,12 @@ Checks if a value is greater than zero.
 #### Exception thrown
 `System.ArgumentOutOfRangeException` if the specified value is lower than zero.
 
+## IsNotEmpty
+Checks if a collection is not empty.
+
+#### Execption thrown
+`System.ArgumentException` if the specified value is empty.
+
 ## IsLowerThan
 Checks if a value is lower than a maximal limit.
 

docs/index.md

@@ -19,14 +19,14 @@ The entry point of the library is the static propery `MGR.Guard.Guardian.ChecksT
 The methods allow you to guard against null value, lower or upper bound, file existence.
 If the check fails, an exception is thrown.
 
+You can find all [built-in methods here](guard.md), or [browse the API](/api).
+
 All built-in methods exists in two flavors:
 
 1. The first takes the value to check and the name of the value (to provide to the thrown exection),
 2. The second takes [an expression](guard-expression.md) from which the value and its name are extracted.
 
-*The first form is much more performant (~600x), but the second one is more maintenable.**
-
-You can find all [built-in methods here](guard.md), or [browse the API](/api).
+*The first form is much more performant (~600x), but the second one is more maintenable.*
 
 ## What if the provided methods are not enough?
 

src/MGR.Guard.Sources/GuardianExtensions.IsNotEmpty.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Collections;
+using System.IO;
+using System.Linq.Expressions;
+using JetBrains.Annotations;
+
+namespace MGR.Guard
+{
+#if MGR_GUARD_PUBLIC
+    public
+#else
+    internal
+#endif
+        static partial class GuardianExtensions
+    {
+        /// <summary>
+        ///     Checks that the specified <see cref="IEnumerable " /> <paramref name="expression" /> is empty.
+        /// </summary>
+        /// <param name="source">The <see cref="Guardian"/> to extends.</param>
+        /// <param name="expression">The collection as an Expression.</param>
+        [PublicAPI]
+        public static void IsNotEmpty([NotNull] this Guardian source, [NotNull] Expression<Func<IEnumerable>> expression)
+        {
+            source.IsNotNull(expression, nameof(expression));
+
+            var (collection, parameterName) = ((IGuardian)source).ExtractValueAndParameterNameFromExpression(expression);
+            IsNotEmpty(source, collection, parameterName);
+        }
+        /// <summary>
+        ///     Checks if the specified <see cref="FileSystemInfo " /> <paramref name="collection" /> exists.
+        /// </summary>
+        /// <param name="source">The <see cref="Guardian"/> to extends.</param>
+        /// <param name="collection">The file.</param>
+        /// <param name="parameterName">The name of the file parameter.</param>
+        [PublicAPI]
+        public static void IsNotEmpty([NotNull] this Guardian source, [NotNull] IEnumerable collection, string parameterName)
+        {
+            source.IsNotNull(collection, nameof(collection));
+
+            var enumerator = collection.GetEnumerator();
+            var hasItems = enumerator.MoveNext();
+            if (!hasItems)
+            {
+                throw new ArgumentException(Messages.IsNotEmptyMessage, parameterName);
+            }
+        }
+    }
+}

src/MGR.Guard.Sources/GuardianExtensions.cs

@@ -35,6 +35,7 @@ private static class Messages
             internal const string IsLowerThanOrEqualToZeroMessage = "The argument must be lower than or equal to 0.";
             internal const string IsDefinedType = "TEnum must be an enumerated type.";
             internal static Func<TEnum, Type, string> IsDefinedFormat<TEnum>() => (value, enumType) => string.Format(CultureInfo.CurrentCulture, "The value '{0}' is not defined in the enum type '{1}'.", value, enumType);
+            internal const string IsNotEmptyMessage = "The collection cannot be empty.";
         }
     }
 }

src/MGR.Guard.Sources/MGR.Guard.Sources.csproj

@@ -22,6 +22,9 @@
       <Pack>true</Pack>
       <PackagePath>$(ContentTargetFolders)\cs\$(TargetFramework)\$(PackageId)\%(RecursiveDir)</PackagePath>
     </Compile>
+    <Compile Update="GuardianExtensions.IsNotEmpty.cs">
+      <PackagePath>$(ContentTargetFolders)\cs\$(TargetFramework)\$(PackageId)\%(RecursiveDir)</PackagePath>
+    </Compile>
   </ItemGroup>
 
   <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />

tests/MGR.Guard.UnitTests/GuardianExtensionsTests.IsNotEmpty.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections;
+using System.Linq;
+using Xunit;
+
+namespace MGR.Guard
+{
+    public partial class GuardianExtensionsTests
+    {
+        public class IsNotEmpty
+        {
+            [Fact]
+            public void Collection_Should_Not_Be_Null()
+            {
+                // Arrange
+                IEnumerable collection = null;
+
+                // Act & Assert
+                var actualException = Assert.Throws<ArgumentNullException>(() => Guardian.ChecksThat.IsNotEmpty(collection, nameof(collection)));
+                Assert.Equal("collection", actualException.ParamName);
+            }
+
+            [Fact]
+            public void Collection_Should_Not_Be_Empty()
+            {
+                // Arrange
+                IEnumerable collection = Enumerable.Empty<object>();
+
+                // Act & Assert
+                var actualException = Assert.Throws<ArgumentException>(() => Guardian.ChecksThat.IsNotEmpty(collection, nameof(collection)));
+                Assert.Equal("collection", actualException.ParamName);
+            }
+
+            [Fact]
+            public void Non_Empty_Collection()
+            {
+                // Arrange
+                IEnumerable collection = new []{new object()};
+
+                // Act & Assert
+                Guardian.ChecksThat.IsNotEmpty(collection, nameof(collection));
+            }
+        }
+    }
+}

tests/MGR.Guard.UnitTests/MGR.Guard.UnitTests.csproj

@@ -6,6 +6,8 @@
         <DocumentationFile />
         <IsPackable>false</IsPackable>
         <RootNamespace>MGR.Guard</RootNamespace>
+        <VSTestLogger>trx%3bLogFileName=$(MSBuildProjectName).trx</VSTestLogger>
+        <VSTestResultsDirectory>$(MSBuildThisFileDirectory)/TestResults/$(TargetFramework)</VSTestResultsDirectory>
     </PropertyGroup>
 
     <ItemGroup>