public void PublicFetchOrCreateItemPassesArgument()
{
// Arrange
ReaderWriterCacheHelper <int, string> helper = new ReaderWriterCacheHelper <int, string>();
Dictionary <int, string> cache = helper.PublicCache;
// Act
string item = helper.PublicFetchOrCreateItem(42, (string argument) => argument, "new");
// Assert
Assert.Equal("new", cache[42]);
Assert.Equal("new", item);
}
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);
}
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);
}
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.AreEqual("original", cache[42], "Cache should have been updated.");
Assert.AreEqual("original", firstItem);
return("new");
};
// Act
string secondItem = helper.PublicFetchOrCreateItem(42, creator);
// Assert
Assert.AreEqual("original", cache[42], "Cache should not have been updated by outer thread.");
Assert.AreEqual("original", secondItem);
}
