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 MustContain assertion for ImmutableArray<T>.

Tasks for this issue

• The production code should be placed in the Light.GuardClauses project. Extend the existing Check.MustContain.cs in the root folder of the project.
• In this file, add several extension method overloads called MustContain for ImmutableArray<T>. They should be placed in the existing 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 throws the default exception (in this case the existing MissingItemException). The actual exception is thrown in the Throw class, you need to call the existing method for it in this class.
• 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 missing item.
• Create unit tests for both overloads. The corresponding tests should be placed in Light.GuardClauses.Tests project, in the existing file 'CollectionAssertions/MustContainTests.cs'. 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.
• 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.
• The assertion should verify that the ImmutableArray<T> contains the specified item.
• If you have any questions or suggestions, please ask me about them.