NUnit2011

Use ContainsConstraint for better assertion messages in case of failure

Topic	Value
Id	NUnit2011
Severity	Info
Enabled	True
Category	Assertion
Code	StringConstraintUsageAnalyzer

Description

Using constraints instead of boolean methods will lead to better assertion messages in case of failure.

Motivation

Using Does.Contain (or Does.Not.Contain) constraint will lead to better assertion messages in case of failure, so this analyzer marks all usages of string Contains method where it is possible to replace with Does.Contain constraint.

[Test]
public void Test()
{
    string actual = "...";
    string expected = "...";
    Assert.True(actual.Contains(expected));
}

How to fix violations

The analyzer comes with a code fix that will replace Assert.True(actual.Contains(expected)) with Assert.That(actual, Does.Contain(expected)). So the code block above will be changed into

[Test]
public void Test()
{
    string actual = "...";
    string expected = "...";
    Assert.That(actual, Does.Contain(expected));
}

Configure severity

Via ruleset file

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

Via .editorconfig file

# NUnit2011: Use ContainsConstraint for better assertion messages in case of failure
dotnet_diagnostic.NUnit2011.severity = chosenSeverity

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

Via #pragma directive

#pragma warning disable NUnit2011 // Use ContainsConstraint for better assertion messages in case of failure
Code violating the rule here
#pragma warning restore NUnit2011 // Use ContainsConstraint for better assertion messages in case of failure

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

#pragma warning disable NUnit2011 // Use ContainsConstraint for better assertion messages in case of failure

Via attribute [SuppressMessage]

[System.Diagnostics.CodeAnalysis.SuppressMessage("Assertion",
    "NUnit2011:Use ContainsConstraint for better assertion messages in case of failure",
    Justification = "Reason...")]