Q & A From “Unit Tests for SSIS Packages”

I did a webinar this week for Pragmatic Works’ “Free Training on the T’s”. The topic was “Unit Tests for SSIS Packages”. If you attended, thanks for taking the time! If not, the recording is now available at the link above. You can also download the slides from my SkyDrive, and ssisUnit can be downloaded from CodePlex.

We had great turnout for the session, and a lot of great questions. I didn’t have time to address all of them during the webinar, and I had a number of requests to share my answers with all the attendees, so I thought I’d write up a blog post on the questions that I didn’t get a chance to answer.

Testing Practices

“For test drive development, should a “final test” (of sorts) be performed after the “refactor” phase to ensure that the act of refactoring didn’t negatively alter the code?”

Yes, absolutely. You want to run your tests after any code changes. This helps ensure that code continues working as expected, and that you don’t have hidden “side effects” associated with your changes.

“How would you unit test a package that is performing transforms in the source query?”

I would create a known set of data in a test version of the source database. I would then create a unit test for the data flow task that checks that the output includes the data with the proper transformations. This will get much easier in a future release, when it will support data flow component testing in the unit test harness, allowing you to test the results of a source component directly.

“What is the best way to incorporate SSIS testing on existing packages to automate..as this also needs requirement breakdown?”

I approach this in the same way that I approach adding tests to an existing .NET application. Start by identifying a subset of existing packages  to work with, and add tests to those. Once those have adequate coverage, move on to the next set. As far as requirements breakdown – yes, you do need to understand what the package is supposed to do in order to test it properly. You can add some simple test cases without a great deal of analysis (for example, did the task execute successfully?) but to get real value out of the tests, they do need to check that the task carries out the requirements as intended.

There is the option of generating unit tests automatically for existing packages via the ssisUnit API. While this can improve code coverage, I would caution you not to rely on it to verify real functionality.

“Sorry I missed the first part of the talk. so not sure if you already talked about this. But how do you recommend creating test data for dimensions if you need to use synthetic data? Are there any tools you recommend using?”

Remember that unit and integration testing is more about verifying functionality, and less about performance. So I like to create a small amount of handcrafted test data that hits the specific scenarios that I need to validate. I find that most of the tools out there for generating data tend to work well if I want large volumes of test data, but not so well for concrete examples. For example, when I need to validate that the package handles a Type 2 SCD update that affects multiple rows correctly, I need 3 to 5 rows of test data that are very specific. Data generators don’t do that very well.

Automating ssisUnit in Builds

“Can we automate the ssisUnit with build & deployments in TFS?” and “How would you enable automated testing with ssisUnit for Continuous Integration?”

The simplest way to to incorporate ssisUnit into your builds is by calling the command line test execution tool. It’s called ssisUnitTestRunner2008.exe (substitute the appropriate version number for your version of SSIS) and you can find it in the folder where you installed ssisUnit.

Another approach is to use the ssisUnit API, but this requires some level of .NET or PowerShell coding.

Compatibility

“Is ssisUnit backward compatible with VS2008?” and “Is this framework compatible with MS SQL Server 2012?”

It does work against 2008 and 2012. You can download the 2008 version directly from the CodePlex site. For 2012, you need to download and compile the source currently, which can be done with the free Express version of Visual Studio. The next release will have separate setups for each version.

“Does the SSIS unit testing work with evaluation edition of BIDS 2008 R2?”

Yes, it does.

“Will this connect with the Microsoft Parallel Data Warehouse?”

I have not tested this myself. However, because it uses standard OLEDB and ADO.NET connection technology for database access, I don’t see any reason why it wouldn’t work.

“I am a SQL 2008 R2 user.  What version of VS is John running?  What were those testing menu options?”

I was running SQL 2012 for the demo. The menu option for running ssisUnit was created using the External Tools menu option under the Tools menu in VS.

Setting Up and Using Tests

“I’m lost.  How did you set up the tests using the GUI and then link it to the SSIS package?  Did i miss that?”

During the demo, I showed a prebuilt ssisUnit test, that I opened in the ssisUnit UI tool. The unit tests are linked to packages through Package Reference objects, which basically refer to a package by it’s file path, or location in SQL Server.

“Can you use a different operator then equal to? Like greater than, less than, different than?”

Yes, the Asserts in ssisUnit can use expressions. These are C#-based expressions that evaluate to True or False. You can use an expression like “((DateTime)result).Date==DateTime.Now.Date” to check that the result of the Assert command is equal to today’s date. “result”, in the expression, represents the object returned by the command associated with the Assert. You can apply pretty much any C# / .NET operation to the result object. For more examples, check out this page.

“When performing SCD operations, the details of the row need to be inspected rather than just count of rows. How would you test this? Within ssisUnit or another tool?”

Well, I’d use ssisUnit, but I’m not exactly unbiased Smile. Currently, you can do this using the SQL Command, which enables you to retrieve specific row details from the database. In the future, you will be able to do this more directly by testing it in the data flow.

“Did you say the file command can accommodate various file types such as xml, csv, pipe delimited, etc.?”

I didn’t say that (I don’t think), but it will work with pretty much any file. Internally, it uses standard .NET file operations, so it’s very similar to the capabilities of the File System task in SSIS. It doesn’t actually care what format the file is in, it can copy, move, and delete it regardless. For line counts, it counts the number of carriage return / line feeds in the file.

“Do you have a guide on how to setup ssisUnit with SSIS? We have tried using this before, but we couldn’t successfully run the test.”

I’m sorry to hear you had problems with it. The Getting Started guide is admittedly light on content, and I really need to provide a more detailed walkthrough. Please vote for this here if you would like this prioritized over the other changes in the queue.

“I noticed in the code that ssisUnit doesn’t handle password protected packages. When will this be supported?”

I’ve added an issue to track this here. Please vote for it if you use password protected packages, as it will help me prioritize how quickly to address it.

“If possible, can you demo if a container can be executed? Especially a For loop or For Each loop?”

I didn’t have time to demo this during the presentation. Good thing too, because there was an error around handling of containers. This has now been fixed in the source code version of the project.

“When testing in a 64bit environment, is there a specific way to execute ssisUnit when data sources are 32bit?”

Currently, this requires that you compile a 32bit version of the source. In the next release, I will provide both 32-bit and 64-bit versions of the test execution utility.

“Will the new version of ssisUnit for 2012 actually include some bug fixes? We’ve tried the current ssisUnit and it’s pretty buggy.” and “Not a question, just feedback: So there are over 30 bug reports and enhancement requests on CodePlex (including UI bugs, missing parts like handling complex Data Flow logic unit testing, etc.) posted since the posting date in 2008. If you address some of these (particularly the UI bugs) in a new release we might try it again. The biggest lack my organization found is that there’s no support for Data Flow tasks, which are 80% or more of our ETL testing. Just some feedback to keep in mind if you make any updates in the future. I’ll gather any additional bugs that we found in our evaluation back in 2011 and add them to the site when I have time.”

Again, sorry that you have had difficulties with it, and I’d definitely appreciate any feedback you can add to the site. For data flow testing, I do use that fairly successfully today, and a number of other users do as well. Admittedly, component level testing for the data flow would be nice (and it is being worked on) but I’m curious about what is blocking you from using it today. If you can submit your issues to the site, I will look at how to address them.

As far as the number of outstanding requests and UI bugs, well. unfortunately, I don’t get paid for working on open source. So focus on this project tends to take a backseat to demands from paying work. That being said, I do want to address as many of the issues as possible, but I have to prioritize my time pretty heavily these days. If there are items that particularly annoy you, please vote for them, as I do use the votes to determine what I should work on. For the UI, I really don’t enjoy UI work (nor, as evidenced by the current GUI, is it my strongest skill as a developer), so you are unlikely to see any significant updates on that front on the open source project. However, Pragmatic Works has taken an interest in unit testing as of late, and we are investigating offering an enhanced UI that’s integrated with Visual Studio as part of our BI xPress product.

“This makes sense to me, but I don’t understand how I setup a package to match up to the unit test.”

Each test case can reference tasks by name or GUID. GUID is more accurate, as names can conflict if you have multiple tasks with the same name in different containers.

“In package 1, you were getting a table count as a task and then writing a unit test to check the results of that test.  Are you returning the result of the SELECT to a variable and then checking the value stored in the variable or are you directly testing the return value from the execute SQL task?”

The Execute SQL task in that test was designed to store the results of the SQL statement in a variable, so the test is written to check the value of the variable (using a VariableCommand) after the task executes. If you need to get a value directly from the database as part of the test, you can use a SqlCommand.

“Do unit tests always fall under Miscellaneous?”

Yes – the SSIS project structure doesn’t allow for custom folders.

“Would you have a more complex example for the test than the result of a table count?”

The ProductSample test on the website illustrates a few other test scenarios. If there are additional scenarios that you’d like to see examples for, please add an issue or discussion item on the site.

Miscellaneous

“Where I can get some xml to parse my .dtsx packages and only extract all the SQL code and associated SSIS task name?”

I’m not really sure how this relates, honestly. However, to do this, you’d need to either write a fairly complex XSLT transform, or use the SSIS API. Unfortunately, I don’t know of any public example code that illustrates this.

Sharing the Presentation

Many, many variations of “Can I get the slides?”

I mentioned this at the top of the post, but just in case: The recording of the webinar is available here: “Unit Tests for SSIS Packages”. You can  download the slides from my SkyDrive, and ssisUnit can be downloaded from CodePlex.

Thanks again to everyone who attended, and thanks for all the great questions.

Leave a Reply