public void GetContent_ThrowsArgumentNullExceptionIfSourceIsNull()
{
// Arrange
ContentRetrieverService testSubject = CreateContentRetrieverService();
// Act and assert
Assert.Throws <ArgumentNullException>(() => testSubject.GetContent(null));
}
public void GetContent_RetrievesContentOnlyOnceAndCachesContentInMemory()
{
// Arrange
var dummySource = new Uri("C:/dummySource");
var dummyContent = new ReadOnlyCollection <string>(new string[0]);
const string dummyCacheDirectory = "dummyCacheDirectory";
var dummyCancellationToken = new CancellationToken();
Mock <ContentRetrieverService> mockTestSubject = CreateMockContentRetrieverService();
mockTestSubject.CallBase = true;
mockTestSubject.Setup(t => t.GetContentCore(dummySource, dummyCacheDirectory, dummyCancellationToken)).
Callback(() => Thread.Sleep(200)). // Arbitrary sleep duration
Returns(dummyContent);
// Mock<T>.Object isn't thread safe, if multiple threads call it at the same time, multiple instances are instantiated - https://github.com/moq/moq4/blob/9ca16446b9bbfbe12a78b5f8cad8afaa755c13dc/src/Moq/Mock.Generic.cs#L316
// If multiple instances are instantiated, multiple _cache instances are created and GetContentCore gets called multiple times.
ContentRetrieverService testSubject = mockTestSubject.Object;
// Act
var threads = new List <Thread>();
var results = new ConcurrentBag <ReadOnlyCollection <string> >();
for (int i = 0; i < 3; i++) // Arbitrary number of threads
{
var thread = new Thread(() => results.Add(testSubject.GetContent(dummySource, dummyCacheDirectory, dummyCancellationToken)));
thread.Start();
threads.Add(thread);
}
foreach (Thread thread in threads)
{
thread.Join();
}
// Assert
mockTestSubject.Verify(t => t.GetContent(dummySource, dummyCacheDirectory, dummyCancellationToken), Times.Exactly(3));
mockTestSubject.Verify(t => t.GetContentCore(dummySource, dummyCacheDirectory, dummyCancellationToken), Times.Once); // Lazy should prevent GetContentCore from being called multiple times
ReadOnlyCollection <string>[] resultsArr = results.ToArray();
Assert.Equal(3, resultsArr.Length);
Assert.Same(resultsArr[0], dummyContent);
Assert.Same(resultsArr[0], resultsArr[1]); // Result should get cached after first call
Assert.Same(resultsArr[1], resultsArr[2]); // Same relation is transitive
}
