The document discusses xUnit style database unit testing presented by Chris Oldwood, covering topics such as the database development process, test-first development, and continuous integration. It outlines various testing models including NUnit and SQL test models, emphasizes the importance of automation in regression testing, and provides examples of testable behaviors and common assertions. The presentation also addresses deployment testing and considerations for using batch files or SQL scripts in a development environment.

1. xUnit Style Database Unit Testing
ACCU London – 20th
January 2011
Chris Oldwood
gort@cix.co.uk

2. Presentation Outline
• Database Development Process
• The xUnit Testing Model
• Test First Development
• Continuous Integration/Toolchain
• Pub

3. Legacy Database Development
• Shared development environment
• Only integration/system/stress tests
• No automated testing
• Only real data not test data
• Referential Integrity – all or nothing
• No automated build & deployment

4. Ideal Development Process
• Isolation
• Scaffolding
• Automation

5. Example Testable Behaviours
• Default constraint
• Trigger to cascade a delete
• Refactoring to a surrogate key

6. NUnit Test Model
[TestFixture]
public class ThingTests
{
[Test]
public void Thing_DoesStuff_WhenAskedTo()
{
var input = ...;
var expected = ...;
var result = ...;
Assert.That(result, Is.EqualTo(expected));
}
}

7. NUnit Test Runner
• Tests packaged into assemblies
• Uses reflection to locate tests
• In-memory to minimise residual effects
• Output to UI/console

8. SQL Test Model
create procedure test.Thing_DoesStuff_WhenAskedTo
as
declare @input varchar(100)
set @input = ...
declare @expected varchar(100)
set @expected = ...
declare @result varchar(100)
select @result = ...
exec test.AssertEqualString @expected, @result
go

9. SQL Test Runner
• Tests packaged into scripts (batches)
• Uses system tables to locate tests
• Uses transactions to minimise residual
effects
• Output to UI/console

10. SQL Asserts
• Value comparisons (string, datetime, …)
• Table/result set row count
• Table/result set contents
• Error handling (constraint violations)

11. Setup & Teardown
• Per-Fixture (static data)
• Per-Test (specific data)
• Use helper procedures

12. Default Constraint Test
create procedure test.AddingTask_SetsSubmitTime
as
declare @taskid int
declare @submitTime datetime
set @taskid = 1
insert into Task values(@taskid, ...)
select @submitTime = t.SubmitTime
from Task t
where t.TaskId = @taskid
exec test.AssertDateTimeNotNull @submitTime
go

13. Trigger Test
create procedure DeletingUser_DeletesUserSettings
as
...
set @userid = 1
insert into AppUser values(@userid, ...)
insert into AppUserSettings values(@userid, ...)
delete from AppUser where UserId = @userid
select @rows = count(*)
from AppUserSettings
where UserId = @userid
exec test.AssertRowCountEqual @rows, 0
go

14. Unique Key Test
create procedure AddingDuplicateCustomer_RaisesError
as
...
insert into Customer values(‘duplicate’, ...)
begin try
insert into Customer values(‘duplicate’, ...)
end try
begin catch
set @threw = 1
end catch
exec test.ErrorRaised @threw
go

15. Automation
• Enables easy regression testing
• Enables Continuous Integration
• Performance can be variable

16. Test First Development
• Start with a requirement
• Write a failing test
• Write production code
• Test via the public interface

17. The Public Interface
• Stored procedures
• Views
• Tables?

18. Implementation Details
• Primary keys
• Foreign keys
• Indexes
• Triggers
• Check constraints
• Default constraints

19. Deployment Testing
Build version N+1
then run unit tests
Build version N
then patch to N+1
then run unit tests
==

20. Buy or Build?
• Batch file, SQL scripts & SQLCMD
• TSQLUnit & PL/Unit
• Visual Studio
• SQL Server/Oracle Express

21. “The Oldwood Thing”
http://chrisoldwood.blogspot.com
Chris Oldwood
gort@cix.co.uk