Issue 118 must have length in for immutable array

Code/Light.GuardClauses.Tests/CollectionAssertions/MustHaveLengthInTests.cs

@@ -0,0 +1,71 @@
+using System;
+using System.Collections.Immutable;
+using FluentAssertions;
+using Xunit;
+
+namespace Light.GuardClauses.Tests.CollectionAssertions;
+
+public static class MustHaveLengthInTests
+{
+    [Theory]
+    [MemberData(nameof(LengthInRangeData))]
+    public static void LengthInRange(ImmutableArray<int> array, Range<int> range) =>
+        array.MustHaveLengthIn(range).Should().Equal(array);
+
+    public static readonly TheoryData<ImmutableArray<int>, Range<int>> LengthInRangeData =
+        new ()
+        {
+            { [1, 2, 3], Range.FromInclusive(0).ToExclusive(10) },
+            { [1, 2, 3, 4, 5], Range.FromInclusive(3).ToInclusive(5) },
+            { ImmutableArray<int>.Empty, Range.FromInclusive(0).ToExclusive(100) },
+            { [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], Range.FromExclusive(5).ToInclusive(10) },
+        };
+
+    [Theory]
+    [MemberData(nameof(LengthNotInRangeData))]
+    public static void LengthNotInRange(ImmutableArray<int> array, Range<int> range)
+    {
+        var act = () => array.MustHaveLengthIn(range, nameof(array));
+
+        act.Should().Throw<ArgumentOutOfRangeException>()
+           .And.Message.Should().Contain($"must have its length in between {range.CreateRangeDescriptionText("and")}")
+           .And.Contain($"but it actually has length {array.Length}");
+    }
+
+    public static readonly TheoryData<ImmutableArray<int>, Range<int>> LengthNotInRangeData =
+        new ()
+        {
+            { [1, 2, 3], Range.FromInclusive(10).ToInclusive(20) },
+            { [1, 2, 3, 4], Range.FromExclusive(4).ToExclusive(10) },
+            { ImmutableArray<int>.Empty, Range.FromInclusive(1).ToExclusive(50) },
+            { [1, 2], Range.FromInclusive(100).ToExclusive(256) },
+        };
+
+    [Fact]
+    public static void CustomException() =>
+        Test.CustomException(
+            ImmutableArray.Create(1, 2, 3),
+            Range.FromInclusive(5).ToInclusive(10),
+            (array, r, exceptionFactory) => array.MustHaveLengthIn(r, exceptionFactory)
+        );
+
+    [Fact]
+    public static void CustomMessage() =>
+        Test.CustomMessage<ArgumentOutOfRangeException>(
+            message => ImmutableArray.Create(1, 2, 3).MustHaveLengthIn(
+                Range.FromInclusive(42).ToInclusive(50),
+                message: message
+            )
+        );
+
+    [Fact]
+    public static void CallerArgumentExpression()
+    {
+        var testArray = ImmutableArray.Create(1, 2, 3, 4, 5);
+
+        var act = () => testArray.MustHaveLengthIn(Range.FromInclusive(10).ToExclusive(20));
+
+        act.Should().Throw<ArgumentOutOfRangeException>()
+           .WithParameterName(nameof(testArray));
+    }
+}

Code/Light.GuardClauses/Check.MustHaveLengthIn.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Immutable;
 using System.Runtime.CompilerServices;
 using JetBrains.Annotations;
 using Light.GuardClauses.ExceptionFactory;
@@ -57,4 +58,51 @@ public static string MustHaveLengthIn(
 
         return parameter;
     }
+
+    /// <summary>
+    /// Ensures that the <see cref="ImmutableArray{T}" />'s length is within the specified range, or otherwise throws an <see cref="ArgumentOutOfRangeException" />.
+    /// </summary>
+    /// <param name="parameter">The <see cref="ImmutableArray{T}" /> to be checked.</param>
+    /// <param name="range">The range where the <see cref="ImmutableArray{T}" />'s length must be in-between.</param>
+    /// <param name="parameterName">The name of the parameter (optional).</param>
+    /// <param name="message">The message that will be passed to the resulting exception (optional).</param>
+    /// <exception cref="ArgumentOutOfRangeException">Thrown when the length of <paramref name="parameter" /> is not within the specified <paramref name="range" />.</exception>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static ImmutableArray<T> MustHaveLengthIn<T>(
+        this ImmutableArray<T> parameter,
+        Range<int> range,
+        [CallerArgumentExpression("parameter")] string? parameterName = null,
+        string? message = null
+    )
+    {
+        if (!range.IsValueWithinRange(parameter.Length))
+        {
+            Throw.ImmutableArrayLengthNotInRange(parameter, range, parameterName, message);
+        }
+
+        return parameter;
+    }
+
+    /// <summary>
+    /// Ensures that the <see cref="ImmutableArray{T}" />'s length is within the specified range, or otherwise throws your custom exception.
+    /// </summary>
+    /// <param name="parameter">The <see cref="ImmutableArray{T}" /> to be checked.</param>
+    /// <param name="range">The range where the <see cref="ImmutableArray{T}" />'s length must be in-between.</param>
+    /// <param name="exceptionFactory">The delegate that creates your custom exception. <paramref name="parameter" /> and <paramref name="range" /> are passed to this delegate.</param>
+    /// <exception cref="Exception">Your custom exception thrown when the length of <paramref name="parameter" /> is not within the specified range.</exception>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    [ContractAnnotation("exceptionFactory:null => halt")]
+    public static ImmutableArray<T> MustHaveLengthIn<T>(
+        this ImmutableArray<T> parameter,
+        Range<int> range,
+        Func<ImmutableArray<T>, Range<int>, Exception> exceptionFactory
+    )
+    {
+        if (!range.IsValueWithinRange(parameter.Length))
+        {
+            Throw.CustomException(exceptionFactory, parameter, range);
+        }
+
+        return parameter;
+    }
 }

Code/Light.GuardClauses/ExceptionFactory/Throw.ImmutableArrayLengthNotInRange.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
+using JetBrains.Annotations;
+
+namespace Light.GuardClauses.ExceptionFactory;
+
+public static partial class Throw
+{
+    /// <summary>
+    /// Throws the default <see cref="ArgumentOutOfRangeException" /> indicating that an <see cref="ImmutableArray{T}" />'s length is not within the
+    /// given range, using the optional parameter name and message.
+    /// </summary>
+    [ContractAnnotation("=> halt")]
+    [DoesNotReturn]
+    public static void ImmutableArrayLengthNotInRange<T>(
+        ImmutableArray<T> parameter,
+        Range<int> range,
+        [CallerArgumentExpression("parameter")] string? parameterName = null,
+        string? message = null
+    ) =>
+        throw new ArgumentOutOfRangeException(
+            parameterName,
+            message ??
+            $"{parameterName ?? "The immutable array"} must have its length in between {range.CreateRangeDescriptionText("and")}, but it actually has length {parameter.Length}."
+        );
+}

Code/Plans/issue-118-must-have-length-in-for-immutable-array.md

@@ -0,0 +1,23 @@
+# Issue 118 - MustHaveLengthIn for ImmutableArray
+
+## Context
+
+The .NET library Light.GuardClauses already has several assertions for collections. They often rely on `IEnumerable<T>` or `IEnumerable`. However, these assertions would result in `ImmutableArray<T>` being boxed - we want to avoid that by providing dedicated assertions for this type which avoids boxing. For this issue, we implement the `MustHaveLengthIn` assertion for `ImmutableArray<T>`.
+
+## Tasks for this issue
+
+- [ ] The production code should be placed in the Light.GuardClauses project. The file `Check.MustHaveLengthIn.cs` already exists in the root folder of the project - extend this existing file.
+- [ ] In this file, create several extension method overloads called `MustHaveLengthIn` for `ImmutableArray<T>`. It should be placed in the class `Check` which is marked as `partial`.
+- [ ] Each assertion in Light.GuardClauses has two overloads - the first one takes the optional `parameterName` and `message` arguments and throw the default exception. The actual exception is thrown in the `Throw` class - use the existing `Throw.ValueNotInRange` method which is located in `ExceptionFactory/Throw.Range.cs`.
+- [ ] The other overload takes a delegate which allows the caller to provide their own custom exceptions. Use the existing `Throw.CustomException` method and pass the delegate, the erroneous `ImmutableArray<T>` instance and the range.
+- [ ] The assertion takes a `Range<int>` parameter to specify the valid length range.
+- [ ] Use the `Length` property of `ImmutableArray<T>` instead of `Count` for performance and correctness.
+- [ ] Create unit tests for both overloads. The corresponding tests should be placed in Light.GuardClauses.Tests project. There is already a file 'StringAssertions/MustHaveLengthInTests.cs' but you need to create a new file 'CollectionAssertions/MustHaveLengthInTests.cs' for collection-related length tests. Please follow conventions of the existing tests (e.g. use FluentAssertions' `Should()` for assertions).
+
+## Notes
+
+- There are already plenty of other assertions and tests in this library. All overloads are placed in the same file in the production code project. The test projects has top-level folders for different groups of assertions, like `CollectionAssertions`, `StringAssertions`, `DateTimeAssertions` and so on. Please take a look at them to follow a similar structure and code style.
+- This assertion specifically targets `ImmutableArray<T>` to avoid boxing that would occur with generic `IEnumerable<T>` extensions.
+- Use the `Length` property instead of `Count` as this is the appropriate property for `ImmutableArray<T>`.
+- The assertion should verify that the `ImmutableArray<T>` length falls within the specified `Range<int>`.
+- If you have any questions or suggestions, please ask me about them.