NUnit2012

NUnit2012

Use StartsWithConstraint.

Topic	Value
Id	NUnit2012
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.StartWith (or Does.Not.StartWith) constraint will lead to better assertion messages in case of failure, so this analyzer marks all usages of string StartsWith method where it is possible to replace with Does.StartWith constraint.

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

How to fix violations

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

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

Configure severity

Via ruleset file.

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

Via #pragma directive.

#pragma warning disable NUnit2012 // Use StartsWithConstraint.
Code violating the rule here
#pragma warning restore NUnit2012 // Use StartsWithConstraint.

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

#pragma warning disable NUnit2012 // Use StartsWithConstraint.

Via attribute [SuppressMessage].

[System.Diagnostics.CodeAnalysis.SuppressMessage("Assertion", 
    "NUnit2012:Use StartsWithConstraint.",
    Justification = "Reason...")]