patkua@work

Building the Testing Pipeline

The point of this workshop was to help bring the ideas of Test Strategy to the forefront of developers writing automated tests, an often considered, essential agile practice. By looking at a small set of automated tests (acceptance, integration, unit), and looking carefully at the different tradeoffs, people in their own project context should more explicitly consider whether or not they have the right ratio of tests (i.e. too many acceptance tests or too many unit tests) with the idea that all of these should be giving you fast feedback in order to have confidence you’re shipping the right thing. All the slides are available on Slideshare here. I ran this workshop at both ACCU2010 and XP2010.

The first part of the workshop was brainstorming a number of types of automated tests before brainstorming the benefits and costs associated with each category of tests. Note that the benefits/costs are relative to your environment. Some (and many more) of the following features are likely to affect this:

The following are sets of tables (in no particular order) transcribing all the different notes.

Acceptance Tests

Benefits Costs
Can be shown to clients Slow
User value ensured Less information available to learn how to do it well
Closer to end requirements Long execution time
Test through layers High learning curve
Easy on legacy code Pin points source of bug
Can be written in some tool (by non developers) Hard to write (well)
Documentation Data dependent
Feeling of completion “done” Requires entire architecture stack/environment
Easier to introduce around legacy code environment cost
Refactoring friendly Continuous updating as features emerge
Documents expected behaviour Can get very verbose
Value centric Expectations must be much clearer
Drive design Costly hardware
Gains confidence that the application does what the user wants Availability of external services
Drives behaviour of the system outside in Test many different configurations
Exercise more code/test Makes changes to “flow” hard
Safety harness Requires infrastructure
Tough to find Brittle and can break for the “wrong” reason
Brittle if through UI

Integration Tests

Benefits Costs
Force communication with 3rd party Hard to set up
Testing external behaviour Require knowledge of context and multiple layers
Less surprises at the end (no big bang integration) Discourages acceptance tests
Requires no GUI Slow
Easier to wrap around legacy code Is hard to keep on a good level
Verifies assumptions about external systems Environment costs
Defines external services Ties implementation to “technical solution”
Flexible Lego tests (pick and choose which ones to run) Authoring to get real data
Platform flexibility Maintenance
Covers configuration Hard to sell in
Complicated/impossible
No IDE
Heavy investment into infrastructure
Pinpointing source of bug
Hard to configure
Detective work

Unit Tests

Benefits Costs
Easy to write Unit tests often on the same level as refactoring -> troubles doing refactorings
Proves that it works Highly coupled to code
Low number of dependencies Might validate unused code
Enable Refactoring Heavy upfront investment in coding time
Becomes system doc(umentation) Hard to maintain
It’s fast feedback “Unit” results in tests on too low a level
Drives simplicity in solutions (if test driven) Inventory: Lines of code
Encourages less coupling, testable design Hard to understand for others than developers
(If pairing or code sharing) -> risk reduction “Many eyes on code” Not effective until critical mass reached (ex: x% code covered)
Helps you take action Difficult in legacy code
Easy to configure Difficult: Developer aversion to doing it
Allows for testing boundary conditions False sense of security
Pinpoints the problem Steep learning curve for developers
Fast to make Tricky mocks
Low individual cost Redundency
Low requirement of domain knowledge

Tool Brainstorm

The following are all the tools brainstormed by the various groups, and grouped accordingly to their recommended classifications (these don’t reflect my views on whether or not they are correctly classified). Leave a comment if you feel like something really should be moved!

Tools for Acceptance Tests

Tools for Integration Tests

Tools for Unit Tests

Other tools not classified

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