NUnit2021

Incompatible types for EqualTo constraint

Description

The EqualTo constraint always fails as the actual and the expected value cannot be equal.

Motivation

class Foo { }
class Bar { }

var foo = new Foo();
var bar = new Bar();

Assert.That(foo, Is.EqualTo(bar));

There is no way that instances of types Foo and Bar could be considered equal, therefore such assertion will always fail.

Testing non-floating point values against NaN is also invalid, as only floating point values can be NaN.

int actual = 5;
Assert.That(actual, Is.Not.NaN);

How to fix violations

Fix your assertion (i.e. fix actual or expected value, or choose another constraint).

Configure severity

Via ruleset file

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

Via .editorconfig file

# NUnit2021: Incompatible types for EqualTo constraint
dotnet_diagnostic.NUnit2021.severity = chosenSeverity

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

Via #pragma directive

#pragma warning disable NUnit2021 // Incompatible types for EqualTo constraint
Code violating the rule here
#pragma warning restore NUnit2021 // Incompatible types for EqualTo constraint

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

#pragma warning disable NUnit2021 // Incompatible types for EqualTo constraint

Via attribute [SuppressMessage]

[System.Diagnostics.CodeAnalysis.SuppressMessage("Assertion",
    "NUnit2021:Incompatible types for EqualTo constraint",
    Justification = "Reason...")]