xunit.AssertMessages

Adds assert messages to all xunit Assert calls.

Usage

Get the nuget package here.

All methods are static on the AssertM class.

Simply add the nuget package to your test project and add

// Alias the assert to quickly migrate existing code to use AssertM.
using Assert = XunitAssertMessages.AssertM;

to your usings. (For an example see the xUnitMessages.Example project.) All asserts will work identical to before but will now have an optional additional parameter that adds a custom message. E.g.

int expectedShippingDelay = 10;
int actualShippingDelay = 9;
Assert.Equal(expectedShippingDelay, actualShippingDelay, "The shipping delay is incorrectly configured.");

will output

Xunit.Sdk.XunitException
The shipping delay is incorrectly configured.

You can include the original message from xUnit via {xMsg}

Example:

Assert.Equal(10, 9, "This is so wrong. {xMsg}");

use double curly brackets with an interpolated string

Assert.Equal(10, 9, $"{9} is so wrong. {{xMsg}}");

Motivation

When working with tools like SpecFlow or other behavior driven frameworks the result of a test is often not read by a programmer but by domain experts. In that scenario an error message like

The vat was calculated incorrectly, the test expects 24.40$ but the calculated value is 34.40$

is a lot more helpful than

Expected: 2440 Actual: 3440

.

The default xunit.assert package does not support custom messages except on the Assert.True and Assert.False methods, but (re-)writing tests with only those two methods is a lot of overhead.

Technical details

Please note the following technical details:

• The type of exception thrown by assert will always be Xunit.Sdk.XunitExcepion
• The original xunit.assert exception will not be included as inner exception, instead the original inner exception will be kept.
• If using {xMsg} to include the original xunit.assert exception message a newline will be prepended. (As most exceptions will already include newlines in their message)