32 lines
1.3 KiB
Markdown
32 lines
1.3 KiB
Markdown
# Custom constraints
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`NUnit` allows you to write test assertions in a more descriptive and human readable way using the [Assert.That](https://github.com/nunit/docs/wiki/Assertions) mechanism, where the first parameter is an object under test and the second parameter describes conditions that the object has to meet.
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## Is
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We’ve extended `NUnit` API with a custom constraint type and declared an overlay `Is` class. To resolve ambiguity between the original implementation and the custom one you must explicitly declare it with a using statement or via addressing through the full type name `UnityEngine.TestTools.Constraints.Is`.
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### Static Methods
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| Syntax | Description |
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| -------------------- | ------------------------------------------------------------ |
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| `AllocatingGCMemory` | A constraint type that invokes the delegate you provide as the parameter of `Assert.That` and checks whether it causes any GC memory allocations. It passes if any GC memory is allocated and fails if not. |
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## Example
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```c#
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using Is = UnityEngine.TestTools.Constraints.Is;
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class MyTestClass
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{
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[Test]
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public void MyTest()
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{
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Assert.That(() => {
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var i = new int[500];
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}, Is.AllocatingGCMemory());
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}
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}
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```
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