xUnit Style Database Unit Testing ACCU London – 20 th January 2011 Chris Oldwood

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

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

Ideal Development Process Isolation Scaffolding Automation

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

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)); }

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

SQL Test Model create procedure test.Thing_DoesStuff_WhenAskedTo as varchar(100) =... varchar(100) =... varchar(100) =... go

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

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

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

Default Constraint Test create procedure test.AddingTask_SetsSubmitTime as int datetime = 1 insert into Task = t.SubmitTime from Task t where t.TaskId exec go

Trigger Test create procedure DeletingUser_DeletesUserSettings as... = 1 insert into AppUser insert into AppUserSettings delete from AppUser where UserId = count(*) from AppUserSettings where UserId exec 0 go

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

Automation Enables easy regression testing Enables Continuous Integration Performance can be variable

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

The Public Interface Stored procedures Views Tables?

Implementation Details Primary keys Foreign keys Indexes Triggers Check constraints Default constraints

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

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

“The Oldwood Thing” Chris Oldwood