Database development unit test with tSQLt
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The document covers a presentation on database unit testing using the TSQLT framework, led by Sergio Govoni on February 27, 2021. It discusses the importance of unit testing, the anatomy of a unit test, and provides a demo for creating and running a unit test for a trigger in SQL Server. The presentation also highlights the benefits of TSQLT and resources for further learning on the topic.
![Isolate stored procedures
tSQLt.SpyProcedure [@ProcedureName = ] 'procedure name'
[, [@CommandToExecute = ] 'command' ]
• It replaces the execution of the stored procedure with the
specified command
• A log table named @ProcedureName_SpyProcedureLog is
created and a new log entry is made for each fake execution
of the “spied” procedure
• https://bit.ly/2XWVZBl](https://image.slidesharecdn.com/database-development-unit-test-with-tsqlt-210227141528/85/Database-development-unit-test-with-tSQLt-24-320.jpg)
Database development unit test with tSQLt
- 1. #datasatpn February 27th, 2021 Data Saturday #1 Database development unit test with tSQLt Sergio Govoni Slide and demo: https://bit.ly/37Sa4oG https://twitter.com/hackerrank/status/607223964469846018
- 2. #datasatpn February 27th, 2021 Data Saturday #1 A big “Thank you” to our Sponsors
- 4. Agenda • Introduction to Unit Testing • Introduction to tSQLt framework • The anatomy of a unit test • Our first unit test
- 5. Types of database unit tests • Structural Testing • Functional Testing • Non-functional Testing
- 6. What is a unit test? • Unit testing is a software testing level that aims to test a discrete piece of code. The “unit” refers to the smallest piece of code that can be tested separately • Unit test • Must be repeatable • Isolates the code under test from the rest of the code • Doesn’t test how the unit interacts with other units
- 7. What is a unit test? • Unit test have to test one question at a time and that question should reflect a requirement for our code • Unit testing is about confirming that all the individual parts work, not that they work together • Unit tests is usually written by the Development Team
- 8. System Under Test (SUT) • In a database solution, the “unit” you want to test is typically a stored procedure, a trigger or a user-defined function • It is very important to define the System Under Test (SUT) first and isolate it! • System Under Test must not be influenced by other procedures or functions called within the one you want to test
- 9. What does a unit test give me? • Unit tests convey safety • Unit tests provide documentation of the software requirements • Unit tests are preparatory to the design phase (TDD methodology), they force you to think how to organize properly • Unit tests simplify the error checking process
- 10. When should I write the unit tests? • Before starting the development? • Focusing on the actual requirements, it minimizes the work for the Developer • During development? • Some tests may need to be reviewed due to development force a change in requirements • After completing the development? • It’s the only option, not the optimal one, if you have already written the code
- 11. Introduction to tSQLt • The framework tSQLt was developed by Sebastian Meine and Dennis Lloyd, it is the open source framework for implementing unit tests in T-SQL for SQL Server • It works with all editions of SQL Server starting from SQL Server 2005 SP2 • It requires SQL CLR enabled
- 12. Introduction to tSQLt • tSQLt is written in T-SQL • It doesn’t work on Azure SQL Database, nowadays • It works on Azure SQL Managed Instances ☺
- 13. Benefits of using tSQLt • Unit tests will be written in T-SQL, you don’t need to learn new programming language • Data manipulation will be rolled back at the end of the test so you don’t need any data cleanup • Mock objects are supported • tSQLt can be integrated into SSDT projects or 3rd party tools
- 14. Benefits of using tSQLt • Tests can be grouped within a single schema • You can use a setup routine for a group of tests or class • The output can be in plain text or XML
- 15. tSQLt Setup: Install in your development DB • Download tSQLt scripts from tsqlt.org/downloads • Enable CLR at the SQL Server instance level • In each development database you want to install tSQLt • Enable TRUSTWORTHY property • Execute tSQLt.class.sql
- 16. Demo tSQLt Setup
- 17. The anatomy of a unit test • Arrange (or Assemble) • Preparation of data on which the test will run • Isolation of the code from any external dependencies • Act • The system under test (SUT) will be executed and the output has been acquired as a result • Assert • The expected result will be compared with the obtained one, the test will fail or will have a positive outcome according to this comparison
- 18. How does a test run with tSQLt • When we run a test through tSQLt, the framework traces the running test and starts a dedicated transaction • The configuration procedure for the test class will be executed (if existing) and afterward the test will be executed • At the end of the test, the tSQLt framework will rollback the dedicated transaction • The results will be stored in the tSQLt.TestResult table
- 19. Our first unit test is for a Trigger ☺ • You developed a Trigger for AdventureWorks2017 to prevent the insertion of new products with values less than 10 as a “safety stock” • The Company Adventure Works LTD wishes to always have a warehouse stock of no less than 10 units for each product • To make our trigger simple, it will only respond to the OnInsert event, for INSERT commands
- 20. Our first unit test is for a Trigger CREATE TRIGGER Production.TR_Product_SafetyStockLevel ON Production.Product AFTER INSERT AS BEGIN /* Avoid to insert products with safety stock level lower than 10! */ DECLARE @SafetyStockLevel SMALLINT; SELECT @SafetyStockLevel = SafetyStockLevel FROM inserted; IF (@SafetyStockLevel < 10) BEGIN -- Error!! EXEC Production.usp_Raiserror_SafetyStockLevel @Message = 'Safety stock level cannot be lower than 10!'; END; END;
- 21. Possible test • Try to insert one correct row • Try to insert one wrong row and observe the error caught by the Trigger • Try to insert multiple rows in a single statements • Wrong and correct rows • Does the order matter? • Let’s start!! ☺
- 22. Demo Let’s write our first unit test!
- 23. Isolate dependencies • Tests often depend on data or the result of a stored procedure or function • This affects our test’s repeatability • We can’t rely on data being unchanged • We need to isolate • Data • Table constraints • Stored procedures • Functions
- 24. Isolate stored procedures tSQLt.SpyProcedure [@ProcedureName = ] 'procedure name' [, [@CommandToExecute = ] 'command' ] • It replaces the execution of the stored procedure with the specified command • A log table named @ProcedureName_SpyProcedureLog is created and a new log entry is made for each fake execution of the “spied” procedure • https://bit.ly/2XWVZBl
- 25. Summary • We discussed about the importance of unit testing applied to database development • We learn how to use tSQLt framework • We learned how to write our first unit test using tSQLt Think about triggers, SP and complex functions you wrote (those with more than 200 lines of code just to be clear ☺) would you feel safe in modifying them? If the answer is “No” the first thing to do is to write the unit tests, now you know how!
- 26. Resources • Articles • What it is and why it is important for T-SQL code • https://bit.ly/3tfUTP8 • The tSQLt framework and the execution of a test • https://bit.ly/3oFy1Fb • How to write your first unit test for T-SQL code • https://bit.ly/3qkBRFq • tSQLt - https://tsqlt.org
- 27. Resources • Videos • Implementare unit testing su Sql Server - Alessandro Alpi • https://www.youtube.com/watch?v=7tIHg3P0ea0 • Continuous Deployment, portare SQL Server nel mondo DevOps - Alessandro Alpi • https://www.youtube.com/watch?v=1jBm4MFFlPg • Tools • Red-Gate SQL Test • https://www.red-gate.com/products/sql-development/sql-test/ • TSQLUnit • https://github.com/aevdokimenko/tsqlunit
- 29. #datasatpn February 27th, 2021 Data Saturday #1 Thanks! #datasatpn @segovoni Slide and demo: https://bit.ly/37Sa4oG