What is the inverse of Contains.Key() for a Dictionary?

[Chris Oldwood]

I have one test that checks for the presence of a key like this:

{

  var dictionary = new Dictionary<string, object>();

  dictionary.Add("test", new object());

  Assert.That(dictionary, Contains.Key("test"));

}

However I cannot work out what the correct fu is for saying "does not contain the key X". After I get past "Does.Not" there only appears to be constraints for checking generic collections, not dictionaries.

I can of course write:

Assert.That(dictionary.ContainsKey("test"), Is.False);

but what I expected to write was something like this:

Assert.That(dictionary, Does.Not.ContainKey("test"));

So, what am I missing here? :o)

Cheers,

Chris Oldwood

[Charlie Poole]

Hi Chris,

You are correct that this is missing per se. However you can use

Assert.That(dictionary.Keys, Does.Not.Contains("test"));

Sorry about the bad grammar. :-)

The Contains class is pretty primitive. It could probably use "No" as
an addition and ConstraintExpression (the Type you get after the No)
should have Key in it or something similar.

If you can come up with a set of dictionary-related expressions you
would like to use, please file an issue and we'll see what we can do.

Charlie

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[Chris Oldwood]

Thanks Charlie.

In the end I created a local extension method so I could write Does.Not.ContainKey("test") to see how it would work out:

public static class Extensions

{

    public static DictionaryContainsKeyConstraint ContainKey(this ConstraintExpression constraint, string value)

    {

        var keyConstraint = new DictionaryContainsKeyConstraint(value);

        constraint.Append(keyConstraint);

        return keyConstraint;

    }

}

This (ContainKey) is the only one that I've come across so far that's missing. Would you still like an Issue raised just for that? If I have time I could look at adding it myself directly (instead of the extension method approach) and send a PR, would you be interested in that route?

Chris Oldwood

[Rob Prouse]

Chris,

A pull request would be welcome. Please enter an issue first so we can track the pull request against it. If you need any help with the pull request, just let me know.

Rob

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[Charlie Poole]

A PR would be great. Thanks.

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