better practices for crafting automated tests

Better Practices for CraftingAutomated Tests

Bj Rollison, Principal Test Architect, Microsoft, Inc.Bj.Rollison@TestingMentor.comhttp://TestingMentor.com@TestingMentor

Introduction

• Ideas for people who automate tests!• Not a discussion of general automation

usefulness or pros and cons• Not about processes• And not about automation strategies

• Assumptions about the audience• You are experienced writing automated tests using a programming language• You want to improve your automation reliability and maintainability• You want to make your automation more robust

Overview

• Basic tenets• 5 practices for developing automated tests

1. Get Organized2. Less is more3. Logging4. Common mistakes5. Expand & explore

• Questions

Basic tenets

• Automate tests that provide information that enables your team to make decisions • Critical functionality – regressions, monitoring• Non-functional – performance, stress, etc.• Behaviors – Customer scenarios

• Be a control freak!• Don’t assume anything• Assume the automated test will fail 30 seconds after you leave

for the night• Your automated must be able to predict and respond to

anomalies in the system

• Code early! (esp. unit tests and API tests)

Get Organized

• Templates provide consistency • Objective explains

purpose of test• Test steps help keep

focus & check assumptions• Report results• Pass / Fail• Blocked

Get Organized

• Source control!• Use source control…period!• Automation code is project

code!• Commit early & often

IDE

• Static analysis • Clean code!• Improves readability• Improves robustness – prevents

common errors• Don’t forget peer or code reviews!• Coding guidelines

Less is more!

• Test scripts focustoo much on coding• Many execution

steps repeated in other tests• Difficult to read• Expensive to

maintain

Open a file

Replace all text

Save the file

Launch app

Close app

Get handle

22 program statements

reduced to 6

Less is more!

• Move the work out of the test and into reusable methods• Use custom

methods to wrap complex tasks• Helper methods

throw exceptions• If method fails,

test is blocked

Oracles• Oracles report

pass or fail results• Separate oracles

from test code.• More == better!• Multiple checks• Catch each

unique exception• Re-throw to

preserve the stack.

Logging & Commenting

• Logging• Log more than you think you need• If you can’t determine cause of failure

from your log files, you aren’t logging (or capturing) enough information.• Logging test steps (other details) should be approximately 50% of test code.

• Commenting• No one can read your mind; especially if you aren’t around• Comments help you and others understand/debug your code• Explain workarounds in your code

Logging

• Logger.TestStep – applicationtask or manipulation• Logger.Comment –

additional notes• If any method throws

an exception; test reports as blocked• Don’t forget cleanup!

CodeComments• Explain what your

custom methods do!• Either code

comments or useLogging.Comment() method• Follow

coding styleguidelines!!!

Log files

• Log files should capture information why a test is blocked or fails• Don’t let blocked (or failing tests) stop your automation from running

Common pitfalls

• Hard coded variables• What happens if this test is ran

on non-EN-US language version?• What about resolution changes?

• No exception handling• What happens when the find

replace dialog doesn’t appear?

• What just happened here?• How do we know if this test passed,

failed, or is blocked?• Is this a test or a macro?

Exploratory automation

• Introducing smart variation into an automated test• Managers generally don’t like randomness in

automation.• So, call it something else; “equivalent variation”• Benefits• Increased test/data coverage• Increased data coverage

• Drawbacks• Unreliability (false positives)• More work

ExploratoryAutomation• Find Replace Example• Find word –• Randomly select a

word from any word in the document

• Replace word• Select a word from

list of words not in document• Random string

DataVariation• Generate

random seed value each iteration• Replace static

variables with real variables• Oracle doesn’t

change!

Summary

• Organize • Templates, coding guidelines, static analysis tools

• Less is more • Optimize test frameworks to facilitate writing tests; not code

• Logging and Comments• More is better

• Common mistakes• Hard coded variables, magic numbers, US centric, etc.Expand & explore

• Exploratory automation• Design tests to expand and explore variations in data, state traversals, etc.

Thanks for listening!