如何在MSTest中处理IDisposable fixture成员

我有一个测试类，里面有一些IDisposable项。这是我第一次尝试这样做：

private MemoryStream toolExampleMs;
private MemoryStream issueClassExampleMs;
private MemoryStream issueTypeExampleMs;
private MemoryStream uniqueIdExampleMs;
private Check exampleCheck;
public SuppressionDatabaseTest()
{
    this.toolExampleMs = new MemoryStream(Encoding.UTF8.GetBytes(toolExample));
    this.issueClassExampleMs = new MemoryStream(Encoding.UTF8.GetBytes(toolExample));
    this.issueTypeExampleMs = new MemoryStream(Encoding.UTF8.GetBytes(issueTypeExample));
    this.uniqueIdExampleMs = new MemoryStream(Encoding.UTF8.GetBytes(uniqueIdExample));
    this.exampleCheck = new Check();
    this.exampleCheck.IssueClass = "FooBarClass";
    this.exampleCheck.IssueType = "FooBarType";
    this.exampleCheck.Key = "FooBarExactWith?Unicode";
}
[ClassCleanup]
public void CleanupAll() // Error: CleanupAll has the wrong signature
{
    toolExampleMs.Dispose();
    issueClassExampleMs.Dispose();
    issueTypeExampleMs.Dispose();
    uniqueIdExampleMs.Dispose();
}
[TestCleanup]
public void Cleanup()
{
    this.toolExampleMs.Seek(0, SeekOrigin.Begin);
    this.issueClassExampleMs.Seek(0, SeekOrigin.Begin);
    this.issueTypeExampleMs.Seek(0, SeekOrigin.Begin);
    this.uniqueIdExampleMs.Seek(0, SeekOrigin.Begin);
}

不幸的是，在MSTest中，ClassCleanup方法必须是static，这意味着没有地方挂接要处理的调用。这是否意味着我需要在每次单独测试前后重建这些流？