FakeItEasy argument constraint being evaluated as null outside of lambda

Question

Using FakeItEasy, I have a setup similar to the one below in one of my tests, and the CallTo assertion at the bottom is failing when setup like this.

var fakedTool = A.Fake<ITool>();

var concreteUnderTest = new Concrete(fakedTool);

concreteUnderTest.doSomething();

var fooConstraint = A<Foo>.That.Matches(f => f.Name.Equals('Alice'));
var barConstraint = A<Bar>.Ignored;

A.CallTo(() => fakedTool.ObservedFunction(fooConstraint , barConstraint))
    .MustHaveHappened(Repeated.Exactly.Once);

I have placed a breakpoint directly above the CallTo line, and the values of fooConstraint and barConstraint are both null.

When I set the assertion up like this, however, it passes:

A.CallTo(() =>
    fakedTool.ObservedFunction(
        A<Foo>.That.Matches(f => f.Name.Equals('Alice')),
        A<Bar>.Ignored
    )
).MustHaveHappened(Repeated.Exactly.Once);

What is causing this behaviour? Is it intended?

score 1 · Accepted Answer · edited May 31 '16 at 14:19

1

This is intended behaviour. You can see the section Always place Ignored and That inside A.CallTo in the docs.

As of FakeItEasy 2.0.0, FakeItEasy will throw an exception when they're stored as variables and invoked, rather than failing quietly by being null.

edited May 31 '16 at 14:19

Blair Conrad

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answered Feb 22 '16 at 18:05

James Monger

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You might as well accept the answer, to signal to readers that it's correct. – Blair Conrad Feb 22 '16 at 18:28
@BlairConrad SO prevents accepting your own answer for 2 days - I will accept in then :) – James Monger Feb 22 '16 at 23:07
1

Ah. I was not aware. Sorry to be a bother. – Blair Conrad Feb 23 '16 at 14:29
No problem @BlairConrad! I didn't know until I tried to click accept yesterday :P – James Monger Feb 23 '16 at 14:32

FakeItEasy argument constraint being evaluated as null outside of lambda

1 Answers1