StringAssert.That Property
Definition
Important
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Gets the singleton instance of the StringAssert functionality.
public static Microsoft.VisualStudio.TestTools.UnitTesting.StringAssert That { get; }[System.Runtime.CompilerServices.Nullable(1)]
public static Microsoft.VisualStudio.TestTools.UnitTesting.StringAssert That { get; }static member That : Microsoft.VisualStudio.TestTools.UnitTesting.StringAssert[<System.Runtime.CompilerServices.Nullable(1)>]
static member That : Microsoft.VisualStudio.TestTools.UnitTesting.StringAssertPublic Shared ReadOnly Property That As StringAssertProperty Value
- Attributes
Examples
The following example defines a custom ContainsWords assertion as an extension method
on StringAssert and invokes it through StringAssert.That:
using System.Collections.Generic;
using Microsoft.VisualStudio.TestTools.UnitTesting;
public static class CustomStringAssertExtensions
{
public static void ContainsWords(this StringAssert stringAssert, string value, IEnumerable<string> words)
{
foreach (string word in words)
{
if (value == null || !value.Contains(word))
{
throw new AssertFailedException($"StringAssert.That.ContainsWords failed. Word <{word}> not found in <{value}>.");
}
}
}
}
[TestClass]
public class MessageTests
{
[TestMethod]
public void Greeting_ContainsExpectedWords()
{
StringAssert.That.ContainsWords("Hello, world!", new[] { "Hello", "world" });
}
}
Remarks
Users can use this to plug-in custom assertions through C# extension methods. For instance, the signature of a custom assertion provider could be public static void ContainsWords(this StringAssert customAssert, string value, ICollection substrings) and the call-site would be StringAssert.That.ContainsWords(value, substrings);.
For new custom assertions, prefer extending That instead, because StringAssert is likely to be deprecated in a future release. For more information, see Extension hooks on StringAssert and CollectionAssert.
