This is a pretty trivial snippet, but I use it quite a lot.
Save this file as testy.snippet in your [Visual Studio]\VC#\Snippets\1033\Test directory.
Then, in the code editor, type testy, TAB+TAB to expand the snippet.
<?xml version="1.0" encoding="utf-8" ?>
<CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
<CodeSnippet Format="1.0.0">
<Header>
<Title>testy</Title>
<Shortcut>testy</Shortcut>
<Description>Code snippet for creating an NUnit unit test in C#</Description>
<Author>James Schubert</Author>
<SnippetTypes>
<SnippetType>Expansion</SnippetType>
</SnippetTypes>
</Header>
<Snippet>
<Declarations>
<Literal>
<ID>summary</ID>
<ToolTip>Summary</ToolTip>
<Default>Summary</Default>
</Literal>
<Literal>
<ID>name</ID>
<ToolTip>Test name</ToolTip>
<Default>TestName</Default>
</Literal>
<Literal>
<ID>description</ID>
<ToolTip>Test Case</ToolTip>
<Default>Assumption_Does_Expectation</Default>
</Literal>
</Declarations>
<Code Language="csharp"><![CDATA[ ///<summary>
/// $summary$
///</summary>
[Test]
public void $name$_When_$description$()
{
// Arrange
// Act
// Assert
}
$end$]]>
</Code>
</Snippet>
</CodeSnippet>
</CodeSnippets>