NUnit2026

Wrong actual type used with the SomeItemsConstraint with EqualConstraint

Topic	Value
Id	NUnit2026
Severity	Error
Enabled	True
Category	Assertion
Code	SomeItemsIncompatibleTypesAnalyzer

Description

The SomeItemsConstraint with EqualConstraint requires the actual argument to be a collection where the element type can match the type of the expected argument.

Motivation

Using Does.Contain or Contains.Item constraints with actual argument, which is either not a collection, or has wrong element type, leads to assertion error.

How to fix violations

Fix the actual value or use appropriate constraint.

Configure severity

Via ruleset file

Configure the severity per project, for more info see MSDN.

Via .editorconfig file

# NUnit2026: Wrong actual type used with the SomeItemsConstraint with EqualConstraint
dotnet_diagnostic.NUnit2026.severity = chosenSeverity

where chosenSeverity can be one of none, silent, suggestion, warning, or error.

Via #pragma directive

#pragma warning disable NUnit2026 // Wrong actual type used with the SomeItemsConstraint with EqualConstraint
Code violating the rule here
#pragma warning restore NUnit2026 // Wrong actual type used with the SomeItemsConstraint with EqualConstraint

Or put this at the top of the file to disable all instances.

#pragma warning disable NUnit2026 // Wrong actual type used with the SomeItemsConstraint with EqualConstraint

Via attribute [SuppressMessage]

[System.Diagnostics.CodeAnalysis.SuppressMessage("Assertion",
    "NUnit2026:Wrong actual type used with the SomeItemsConstraint with EqualConstraint",
    Justification = "Reason...")]