How do I assert that collection contains only one element with given property value?
For example:
class Node
{
private readonly string myName;
public Node(string name)
{
myName = name;
}
public string Name { get; set; }
}
[Test]
public void Test()
{
var array = new[]开发者_如何转开发{ new Node("1"), new Node("2"), new Node("1")};
Assert.That(array, Has.Some.Property("Name").EqualTo("1"));
Assert.That(array, Has.None.Property("Name").EqualTo("1"));
// and how to assert that node with Name="1" is single?
Assert.That(array, Has.???Single???.Property("Name").EqualTo("1"));
}
1: You can use Has.Exactly()
constraint:
Assert.That(array, Has.Exactly(1).Property("Name").EqualTo("1"));
But note since Property is get by reflection, you will get runtime error in case property "Name" will not exist.
2: (Recommended) However, it would be better to get property by a predicate rather than a string. In case property name will not exist, you will get a compile error:
Assert.That(array, Has.Exactly(1).Matches<Node>(x => x.Name == "1"));
3: Alternatively, you can rely on Count
method:
Assert.That(array.Count(x => x.Name == "1"), Is.EqualTo(1));
Why don't use a bit of LINQ?
Assert.IsTrue(array.Single().Property("Name").EqualTo("1")); // Single() will throw exception if more then one
or
Assert.IsTrue(array.Count(x => x.Property("Name").EqualTo("1") == 1); // will not
FluentAssertions has a method ContainSingle (on GenericCollectionAssertions class) and you can call it like
myCollection.Should().ContainSingle();
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