NUnit2056

Consider using Assert.EnterMultipleScope statement instead of Assert.Multiple/Assert.MultipleAsync

Topic	Value
Id	NUnit2056
Severity	Info
Enabled	True
Category	Assertion
Code	UseAssertEnterMultipleScopeAnalyzer

Description

Consider using Assert.EnterMultipleScope statement instead of Assert.Multiple/Assert.MultipleAsync.

Motivation

Prior to NUnit 4.2, developers used two separate methods to group multiple assertions into a single logical assertion:

• Assert.Multiple for synchronous code
• Assert.MultipleAsync for asynchronous code

This approach, while functional, had limitations — in particular around unnecessary context capture and limited static analysis due to the use of lambda expressions.

With the release of NUnit 4.2, a new API was introduced: Assert.EnterMultipleScope. This method unifies the handling of multiple assertions for both sync and async code and avoids the problems above.

For more information on EnterMultipleScope see the discussion in this Feature Request

[Test]
public void TestMultiple()
{
    Assert.Multiple(() =>
    {
        var i = 4;
        var j = 67;
        Assert.That(i, Is.EqualTo(j));
    });
}

and

[Test]
public async Task TestMultipleAsync()
{
    await Assert.MultipleAsync(async () =>
    {
        var i = await GetInt();
        var j = await GetInt();
        Assert.That(i, Is.EqualTo(j));
    });
}

How to fix violations

The analyzer comes with a code fix that will replace Assert.Multiple and Assert.MultipleAsync with using (Assert.EnterMultipleScope()) and keep the body of the methods as body of the using statement. So the methods above will be changed into.

[Test]
public void TestMultiple()
{
    using (Assert.EnterMultipleScope())
    {
        var i = 4;
        var j = 67;
        Assert.That(i, Is.EqualTo(j));
    }
}

and

[Test]
public async Task TestMultipleAsync()
{
    using (Assert.EnterMultipleScope())
    {
        var i = await GetInt();
        var j = await GetInt();
        Assert.That(i, Is.EqualTo(j));
    }
}

Configure severity

Via ruleset file

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

Via .editorconfig file

# NUnit2056: Consider using Assert.EnterMultipleScope statement instead of Assert.Multiple/Assert.MultipleAsync
dotnet_diagnostic.NUnit2056.severity = chosenSeverity

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

Via #pragma directive

#pragma warning disable NUnit2056 // Consider using Assert.EnterMultipleScope statement instead of Assert.Multiple/Assert.MultipleAsync
Code violating the rule here
#pragma warning restore NUnit2056 // Consider using Assert.EnterMultipleScope statement instead of Assert.Multiple/Assert.MultipleAsync

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

#pragma warning disable NUnit2056 // Consider using Assert.EnterMultipleScope statement instead of Assert.Multiple/Assert.MultipleAsync

Via attribute [SuppressMessage]

[System.Diagnostics.CodeAnalysis.SuppressMessage("Assertion",
    "NUnit2056:Consider using Assert.EnterMultipleScope statement instead of Assert.Multiple/Assert.MultipleAsync",
    Justification = "Reason...")]