1. Testing Database Code with tSQLt
Frank Geisler

3. Stick around for SWAG! (Prize drawing at 5.00 p.m)
All our volunteers and organisers do not get paid for running SPS SQLSaturday Cambridge and do it because they believe in the power of community (or are just plain nuts). Please show your gratitude for making this possible by:
Giving them a hug
Shaking their hand
Saying thank you
Coming back next year
Consider getting your company to pay for a precon next year
Speading the word
Getting involved yourself
But most of all, by enjoying the day!
Don’t forget to thank the sponsors for their support
Thank the speakers for donating their time, energy and expenses

4. Stick around for SWAG! (Prize drawing at 5.00 p.m)
SQLCloud — XBox One!!! (make sure you know how to play the Jet Set Willy vendor competition!)
SQLCloud—Dark Side Of The Moon, The Wall and Wish You Were Here
Microsoft — MCP Voucher
Data Idols — Supercar Driving Experience
Profisee — Signed MDS Book and £50 Amazon Voucher
SQLSentry — Plan Explorer PRO License
Pyramid Analytics—Coffee Machine
Effektor — Lego Big Ben
Rencore — SPCAF Professional License (valued at $2099!)
Axioworks — Amazon Fire TV and £75 Amazon Voucher
DELL — Beats by Dr Dre Headphones
Redgate — DLM Workshop
Pluralsight — Annual Plus subscriptions
All Your Base Conference — 3 x Conference Tickets
VisualSP—Annual training subscription
Loads of books and much much more!!!

5. Who Am I…? CEO GDS Business Intelligence GmbH
@FrankGeisler
CEO
GDS Business Intelligence GmbH
Chapter Leader PASS Chapter Ruhrgebiet
Microsoft P-TSP
MVP SQL Server
Author
Speaker
Topics: Business Intelligence, SharePoint, SQL Server
Programming, Software Engineering

6. Agenda Why Unit Tests? What are Unit Tests? What is tSQLt?
How to install and run example
How is tSQLt structured?
SQL Test
How to write a test
Faking Tables

7. Why unit tests? SQL Server only checks syntax not functional errors
Code can be syntactical correct but it might not work as expected

8. What are unit tests? A simple example
Write a simple Stored Function that adds two numbers
Write a test without tSQLt just to demo how unit tests work
Alter the Stored Function to see how it affects the test

9. DEMO
Simple Test without tSQLt |

10. So what are Unit Tests?
Tests a discrete unit of code = self contained proc. or function
Does not test how the proc. or functions interact with other code
Isolation is important – the code that shall be tested should not be affected by other things outside the code
Test should be repeatable
not only meet requiremets once
Good for automation

11. How to write Unit Tests? Build a selection of tests
different sets of input parameters
Max / Min values for parameters
Wrong parameters (to determine how the code will act on them)
IMPORTANT: Test only one question at a time
Series of discrete tests
Each test reflects a requirement to our code
Each test can be tied back to the specification
Unit tests only part of the testing (other test necessary like integration test)

12. What is the result of the unit test?
Confirms that the single parts work, does not confirm that the single parts work together!

13. Who writes unit tests? Developers while writing code Testers
increase code coverage
Tests for exitsing code

14. When write unit tests? After development During development
For existing code
Before refactioring existing production code
Cover instances where bugs have been discovered
During development
Before development
Think about code structure
Focused development – clear line for requirements
Extreme Programming / Agile Methods

15. Pros of unit tests Certainty that codes works as expected
Code meets requirements
Enforces good design practice by having to isolate functionality
More of the design is done in advance
Simple error checking  Unit Tests show which Module fails
Error is either in unit or in test

16. What is tSQLt? tSQLt is Free! (www.tsqlt.org) Based on T-SQL
Tests are Stored Procedures
Smaller than a testing framework outside SQL Server
Can mock objects (like tables) to isolate Code
Utilize power of transactions (rollback changes)
No (potentially) buggy tear down script
Uses CLR  does not run on Azure

17. Install tSQLt Download tsqlt.zip
Enable CLR on Server (only on development server)
Run tsqlt.class.sql

18. DEMO
Install tSQLt and run Example |

19. How is tSQLt Structured in the Database
Schema tSQLt – all the Stored Procedures to setup and run tests
„Test-Classes“: in tSQLt they are Schemas
Tests: Stored Procedure within a test class – must start with the word „test“

20. SQL Test Commercial Product from redgate Nice GUI for tSQLt
Not necessary for using tSQLt (but makes using tSQLt a lot nicer)
Lower barrier to use tSQLt  Adoption might be higher
Can install tSQLt to your database
If you want the newest version of tSQLt install it manually

21. DEMO
Using SQL Test |

22. How to write a test?
Set the scene – isolate test from outside dependencies
Define what will be a sucessful test
Run the object under test and capture output
Compare output of object to expectation

23. What the tSQLt Framework does…
Start a transaction for the test
Run the setup procedure (if any)
Run the test (as defined on the slide before this)
Set the scene – isolate test from outside dependencies
Define what will be a sucessful test
Run the object under test and capture output
Compare output of object to expectation
Rollback transaction

24. Writing new tests Often Test is written before code is written
By default tSQLt assumes that the test passes
DANGEROUS: If a test is not implemented the false impression is raised that everything is OK
Empty Tests pass!
=> Important to avoid false positives

25. The Beer Database

26. The data – View Fact.vOrders

27. View vBeerTypes
Returns all the BeerTypes in the Database

28. Possible Tests Does the Object exist?
Does it have the right output format?
Are the right values returend?

29. DEMO
Writing a new test |

30. Testing the output Data table to be returned Expected set of data
Capture output of object under test
Assert that they are the same
See if assertion is met

31. DEMO
Testing the output |

32. Isolating from the outside
Isolate Object under test from external Influences
Data
Table Constraints
Other Stored Procedures or Functions being called
Not isolating prevents tests from being run automatically and repeatably

33. Isolating from Data Requirement of the Data
Enough to do testing but not too much
Unit test shall run quickly  run them frequently
Use a small portion of realistic data
Possible Solution: Delete Data for test and rollback
Could take a while
Does not isolate all dependencies
Problems with Constraints or Foreign Keys
Extra Effort 

34. FakeTable Takes Tablename to Clone actual table Moves Objects
Fake-Table is without Data and without constraints
Code under test is unchanged
Minimal setup
Test is repeatable

35. DEMO
Faking Tables |

36. Thank you for your attention
Any questions???