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// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
using System.Collections.Generic;
using Xunit;
namespace System.Web.Mvc.Test
{
public class ReaderWriterCacheTest
{
[Fact]
public void PublicFetchOrCreateItemCreatesItemIfNotAlreadyInCache()
{
// Arrange
ReaderWriterCacheHelper<int, string> helper = new ReaderWriterCacheHelper<int, string>();
Dictionary<int, string> cache = helper.PublicCache;
// Act
string item = helper.PublicFetchOrCreateItem(42, () => "new");
// Assert
Assert.Equal("new", cache[42]);
Assert.Equal("new", item);
}
[Fact]
public void PublicFetchOrCreateItemReturnsExistingItemIfFound()
{
// Arrange
ReaderWriterCacheHelper<int, string> helper = new ReaderWriterCacheHelper<int, string>();
Dictionary<int, string> cache = helper.PublicCache;
helper.PublicCache[42] = "original";
// Act
string item = helper.PublicFetchOrCreateItem(42, () => "new");
// Assert
Assert.Equal("original", cache[42]);
Assert.Equal("original", item);
}
[Fact]
public void PublicFetchOrCreateItemReturnsFirstItemIfTwoThreadsUpdateCacheSimultaneously()
{
// Arrange
ReaderWriterCacheHelper<int, string> helper = new ReaderWriterCacheHelper<int, string>();
Dictionary<int, string> cache = helper.PublicCache;
Func<string> creator = delegate()
{
// fake a second thread coming along when we weren't looking
string firstItem = helper.PublicFetchOrCreateItem(42, () => "original");
Assert.Equal("original", cache[42]);
Assert.Equal("original", firstItem);
return "new";
};
// Act
string secondItem = helper.PublicFetchOrCreateItem(42, creator);
// Assert
Assert.Equal("original", cache[42]);
Assert.Equal("original", secondItem);
}
private class ReaderWriterCacheHelper<TKey, TValue> : ReaderWriterCache<TKey, TValue>
{
public Dictionary<TKey, TValue> PublicCache
{
get { return Cache; }
}
public TValue PublicFetchOrCreateItem(TKey key, Func<TValue> creator)
{
return FetchOrCreateItem(key, creator);
}
}
}
}
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