cannot mock TableQuerySegment

I’m writing unit tests for my codes where I need to fake Azure storage. Inside my test codes, I need to mock cloudTable.ExecuteQuerySegmentedAsync(query, continuationToken, cancellationToken) which returns TableQuerySegment<TElement>. However TableQuerySegment has no public contructors so I’m unable to mock it or consturct its instance. What can be done so that I don’t have to call azure actually but get a fake data to continue my tests?

[pdl5p]

I’ve worked around this issue by using reflection to create a mock (well actually a real) instance of TableQuerySegment like so:-

var ctor = typeof(TableQuerySegment<MyEntity>)
                .GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic)
                .FirstOrDefault(c => c.GetParameters().Count() == 1);

var mockQuerySegment = ctor.Invoke(new object[] { new List<MyEntity>() }) as TableQuerySegment<MyEntity>;

[ljsg]

I’ve worked around this issue by using reflection to create a mock (well actually a real) instance of TableQuerySegment like so:-

var ctor = typeof(TableQuerySegment<MyEntity>)
                .GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic)
                .FirstOrDefault(c => c.GetParameters().Count() == 1);

var mockQuerySegment = ctor.Invoke(new object[] { new List<MyEntity>() }) as TableQuerySegment<MyEntity>;

If like me you also need to use the ContinuationToken in your tests you can expand @pdl5p 's code like so:

MethodInfo setTokenMethod = typeof(TableQuerySegment<MyEntity>).GetMethod("set_ContinuationToken", BindingFlags.NonPublic | BindingFlags.Instance);

var continuationToken = new TableContinuationToken();
setTokenMethod.Invoke(mockQuerySegment , new object[] { continuationToken });

cloudTable.Setup(t => t.ExecuteQuerySegmentedAsync(It.IsAny<TableQuery<MyEntity>>(), It.IsAny<TableContinuationToken>()))
                    .Returns(Task.FromResult(mockQuerySegment ))

This can be used to test when ExecuteQuerySegmentedAsync returns a continuation token meaning more results are available from the table