Test Driven Database Development With Data Dude

Test-Driven Database Development with DataDude
Cory Foy
http://coryfoy.com | @cory_foy

Agenda
Overview
Features
Demos
Availability
Other Tools

Overview – TDD
TDD == Test-Driven Development
Developer Design Technique
Red-Green-Refactor
Write a failing test
Write just enough code to make it pass
Refactor any duplication

Overview – TDD in DBs
Why is agility at the database so hard?
Control / Permission issues
Tightly coupled applications
No good testing tools
Data Migration issues
If it hurts, do it more

Overview – Agile Defined
Agile Manifesto
Individuals and Interactions over Processes and Tools
Working Software over Comprehensive Documentation
Responding to Change over Following a Plan
Customer Collaboration over Contract Negotiation

Overview – Agile Defined
Agile Manifesto
Don’t rely on tools and processes to save you
Talk to your data experts, your developers
Find common ground
Make incremental improvements
Build a safety net

Overview – Goals of DataDude
Integrated Change Management for DB Apps
Provide Tools to
Manage DB Projects
Assess effects of changes to the DB
Help work in an isolated environment
Help test Updated Solutions
Simplify the deployment of changes
Facilitate Collaborative Development

Overview - Editions
DataDude (2005) (Add on to VSTS)
Team Edition for Database Professionals (2008)
Visual Studio Team System Database Edition (2010)
Comes for free with VSTS Developer Edition

Overview - Tasks
Create and Deploy DBs under version control
Put existing DBs under version control
Modify Offline Representations and deploy
Compare Schemas and Data between DBs
Develop and run unit tests against DB Objects
Generate repeatable test data
Refactor database changes across the DB

Agenda
Overview
Features
Demos
Availability
Other Tools

Features
Version Control Database
VC a new or existing database
Refactor
Compare DBs
Generate Deployment Script
Unit Test Database
TDD Schema Changes
TDD Business Logic Change
Generate Test Data

Agenda
Overview
Features
Demos
Availability
Other Tools

Demo – Version Control Database
Cory Foy

Existing Schema
Two Tables
- Msgs, Users
Two Stored Procs
- PostMsg: Posts a message for a specific user to the database. Take a UserID and varchar message as a parameter
- UserInfo: Takes a UserID and returns back all of the user information, including how many posts they’ve made

Get Database Under Version Control

You now have an isolated copy you can work with that doesn’t change the source database

We want to change “Msg” to “Neet” everywhere it exists in the database.
This will require a change to the Msg column in the Msgs table, renaming the Msgs table itself, and updating the Stored Procs.
We could do it by hand, or we could use the refactoring tools built in.

We use the Refactoring Option to rename the column, and by selecting “Preview Changes” it shows us what it is going to do

We can even see the change in the context of the DDL by clicking on the change in the preview window.
When we click on Apply, the change is made to the version controlled local copy.

We also need to change the table name, so we can use refactor for that as well.
It detects the need to update the constraints as well

Changing the Stored Proc name can also be done through Refactoring
But changes to the values returned from the UserInfo stored proc would have to be done by hand.
Also note that the refactorings only look at the database – not your code which accesses or uses the database

We can now compare the schema changes to see how this would deploy it to the database

By Default, choosing to deploy creates a script which can be run to do the actual deploy

We can also choose to have it automatically deploy to a database. For example, here we have it deploying to a local SQLEXPRESS Database
And everything should still work (meaning no data loss)

Demo – Unit Test Database
Cory Foy

Unit Test Database
We have a new requirement for scalability. Instead of doing a count for user_info, we want a new table which just has a user_id and count. This field should be updated on every Neet by the user, and should be the one queried to get the current Neet count.
But, we want to make sure that all of our existing scripts work. Unit Testing to the rescue!
Add a new Test Project to our Solution, then delete the UnitTest1.cs file. Then right-click on the Test Project, do a New->Add Item, and select Data -> Database Unit Test. Name it NewNeetUpdatesNeetCount

Unit Test Database
Database Unit Tests execute against a real database connection. So we’ll need to tell it which database to execute against.
Note that in this screen we can Execute the tests using one connection, and validate using a different one. This is important when you have your production code which uses a limited access user.
We’ll also have it automatically deploy the project to the database before the tests are run

Unit Test Database
We now see the DB Test screen. Note that we can have Pre-test, Test and Post-test scripts. These can be used for setting the database into specific states. All tests are written in SQL, and then validated by the Test Conditions at the bottom of the screen.

Unit Test Database
What we’re wanting to test is that, with an existing user who as Neet’d before, when we call the PostNeet stored procedure, that the NeetCount table is updated. So our test will look something like this (Arrange, Act, Assert)
We’ll then need to remove the default test condition (by clicking the Red x)
Then we’ll choose “Scalar Value” from the drop down and hit the plus sign, configuring it to expect that the last query our test runs will return the value “1” in Row 1, Column 1

Unit Test Database
Next, we’ll run the test using the built-in runner. Note that the first time you run the tests, it will be slow because it has to synchronize some information.
You’ll see the test failed, and if you right-click on the test and say “View Test Result Details” you can see the exact error message
The error is that we don’t actually have a table called NeetCount. Well, this will never do, let’s add it.

Unit Test Database
So, do we go to the database? Nope – we make the change right from our project. In our schema view, we click on the Tables node, then choose Add->Table.
We’ll name it NeetCount so we stand a chance of having our unit tests pass.
We’ll also fill out the DDL to have the columns we are looking for and save it.

Unit Test Database
Now we’ll rerun our tests. And they fail again. But for a different reason this time
Yep. Our table is there, but nothing is being inserted. How did our table get there? Remember that when we setup the test we told it to deploy the DB project before running tests. So it added the table to the database before running the tests – just by us clicking Run.

Unit Test Database
Now that our unit test is failing for logic reasons, we can make the change to the stored procedure. Again, we change it by opening it from the Schema view rather than changing the database directly. But look at the proc. We’ve found our first business decision – at what point should UserID records get inserted into NeetCount?
It’s decided that upon user creation a record will get inserted in, and that we’ll need a migration effort to move existing records. With those taken care of, we can focus back on modifying this Proc.
(Yes, we’re ignoring transactions, etc for now)

Unit Test Database
After updating our test database with the migration of data, we can rerun our tests
And everything runs succesfully! Now we know that post a Neet updates the correct count. It’s now time to make sure that UserInfo is pulling the information from the right table

Unit Test Database
We create another Database Unit Test called UserInfoGetsCountFromNeetCount. We’ll update the NeetCount for our test user, then execute the UserInfo and we should see the updated count. We’ll start with choosing the Pre-test option and filling it in, then setting the actual test up
And running our tests shows it fails for the “right” reason

Unit Test Database
So now we’ll modify our UserInfo stored proc to make the test pass.
And it does!

Unit Test Database
While what we’ve done works, it is better to capture the logic of a change like this in a way that shows the business value and the coupling. Let’s create a new Database Unit Test and call it EnhanceUserInformationPerformance. We’ll add two tests in this for the two conditions we covered previously. Use the Rename button to rename the first test, then click the plus sign to add the second test. Copy over the logic for each from the previous tests, making sure to include the Test Conditions and PreTests

Unit Test Database
Now let’s make sure they run. Go to Test->Run All Tests in Solution and they should all pass.
Now, let’s delete the first two tests we created in favor of this new combined test, and rerun all of our tests to make sure.
All well and good so far. But we should write one more test which does everything end-to-end

Unit Test Database
Add a new Database Unit Test and call it NewNeetUpdatesUserInfo. We’ll use a temp table to capture the results of the UserInfo to compare against our expected values. Note that you *can’t* do this in pre/post test since those run in different connections, therefore the variables can’t be shared. So run the tests and see it green.
Right?
Or not. So what happened? Remember our Unit Test which updated the NeetTable directly? It’s polluted our DB, which invalidates our results.

Unit Test Database
To get around that, we need to either run things in transactions (which we have to do all in the Test Script) or back our changes out. In this case, we’ll just revert the changes at the end of the script in Post Test. So modify the UserInfoGetsCountFromNeetCount test and add the following to Post-test
Now go to Test->Run-> All Tests in Solution and what do we see?
That’s much better

Unit Test Database
One thing to note about the Database tests – they are all just code and xml underneath. For example, right-clicking on one of our tests and saying “View Code” shows the “magic” happening underneath
These are just MSTest unit tests, so you can drop to the code level if there are special things you need to do with the tests.

Demo – Generating Data
Cory Foy

Generating Data
In our last demo, we saw the challenges data can cause us. We can use the data generation tool to help us populate the information in our database. Right-Click on the Knitter project in Solution Explorer and choose Add-> Data Generation Plan, then name it TestData.
If you click on dbo.Neets, you’ll see that UserID shows as a Foreign Key, but it doesn’t in dbo.NeetCount (because we didn’t add it). Fix that by Right-Clicking on the NeetCount table in Schema View and choosing Add->Foreign Key. Once you’ve filled it in, deploy it, then refresh the data plan

Generating Data
NeetCount.totalNeets is effectively a computed field, but it’s not. So make sure the generator is Integer, and change the properties to be Max and Min of 1
We also only want our usernames (UserID in the Users table) to only be AlphaNumeric. So change the generator for that column to be Regular Expression, and in the Properties window, enter [a-zA-Z0-9]*_[a-zA-Z0-9]* then right-click on the UserID row and choose “Preview Data Generation”. As you can see, the characters run the gamut.

Generating Data
With our test plan in place, we can have our unit tests use it automatically. Go to Test->Database Test Configuration and check the “Generate Test Data” box.
Now whenever the tests are run, the data is generated automatically.
Let’s rerun our tests to show the difference.
What a difference! They all fail because there is no UserID “1” in the database.

Generating Data
To fix that, we’ll update the tests to select the top user from the users table, making sure we update all 3 tests, and the pre and post tests where necessary.
And that looks much better

Generating Data
If we do an actual query in our test database, we’ll see that indeed the values get inserted there
The Database Edition comes with several generators – for each type, the Regular Expression generator, and Databound generators which can pull data from any connection – other databases, Excel files, CSV files, etc.

Agenda
Overview
Features
Demos
Availability
Other Tools

Availability
Available in VS2005, VS2008 and VS2010
Requires a Team Edition of Visual Studio
Comes with the Team Edition for Software Developers

Availability
Supports SQL 2000, 2005 and 2008
Plans are in place to provide data bindings for other platforms but no timeline

Agenda
Overview
Features
Demos
Availability
Other Tools

Other Tools
DBFit
Supports Oracle, DB2, SQL Server and MySQL
Free of charge
Add on to the FitNesse testing framework
http://www.fitnesse.info/dbfit:reference
http://gojko.net/fitnesse/dbfit/

Other Tools
AnyDbTest
Supports Oracle, SQL Server and MySQL
Uses XML as the backing
http://www.anydbtest.com/

Other Tools
Agile Data – Scott Ambler
Agile Database Techniques
Refactoring Databases
http://www.agiledata.org

More Information
http://msdn.microsoft.com/teamsystem
http://www.infoq.com/articles/tdd-dbpro-Foy
http://blog.coryfoy.com/2007/07/test-driving-stored-procedures-in-sql-server-in-vs2008/
http://www.coryfoy.com
foyc at coryfoy dot com
@cory_foy on Twitter
Slides will be posted on CoryFoy.com

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Test Driven Database Development With Data Dude

by Cory Foy on Feb 02, 2010

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Test Driven Database Development With Data Dude — Presentation Transcript