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The Tao Of Testing

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Martin Burns

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User since: 26 Apr 1999

Articles written: 143

Fred Brooks says

that a third of IT development time and effort

should be spent in testing. In any software development project,

with many people working on the coding, testing is essential to make

sure that the system performs as the requirements say it should.

However, even if you're a developer team of one, you still have an interest

in ensuring that your work has proper Quality Assurance (QA) documentation

for three main reasons:

  1. Your future business depends entirely on your professional reputation -

    good clients will always look for a reputation for delivering their

    requirements. Anything which enhances that reputation is A Good Thing.

  2. Once the system is handed over to the client, you will then have an

    audit trail of testing, documenting that the system is working. If it

    later fails, you have a backup to safeguard you against potential

    legal and reputational action from a panicking client.

  3. If you want to feel self-interested about this (and most of us do at

    some point), remember that the client should pay for all of this testing -

    it's all chargeable time, which will result in the client getting a better

    system at the end of it.

So what do you have to do?

Test Scripts

Testing is a systematic discipline. You need to

ensure that you test every piece of functionality against its specification, and that

tests repeated after a bug has been fixed are the same

as the test which highlighted the bug in the first place.

The best way to ensure that there are no gaps in your test programme

is to produce a test script. This will allow you to check that no

area of functionality slips through the net, either at design stage,

or while the tests are being performed.

Your script should outline the steps which testers will follow,

and list the expected results of each test. The detail you go into

will depend on the time and budget available for testing.

A sensible way of distributing the scripts is electronically - often

as a word processing document. This will allow testers to record any

errors which occur together with the tests which brought them out.

You should archive the documents in read only format with the rest

of the project documentation. To be on the safe side, the testers

should print and sign the sheets, and again, you'll store these with

the documentation.

Types of Testing

Usability Testing

Usability testing should happen before a single element of

the user interface (including information architecture) is

fixed. Performing usability tests at this stage will allow

you to change the interface reasonably quickly and cheaply -

backing out an interface once it is coded is always going

to be difficult.

The best way to perform usability testing at this stage is

to build a prototype of your proposed interface, and test

that. Feedback from the testers will allow you to quickly

amend your prototype and go through another iteration.

Research shows that target="_foo" title="Opens in a new window">you only need to use five testers to

perform the usability tests, and find 85% of the

usability issues
in each iteration. After a few iterations,

you're unlikely to have substantive issues left.

Unit Testing

Typically, a system contains a number of pieces such as

  • 'the bit which displays the product'

  • 'the bit which puts the product into the shopping cart'

  • 'the bit which which verifies the credit card and takes the payment'

and so on. Each of these is a unit, and you need to make sure

that each unit produces the appropriate output for the input you

give it, including sensible error trapping. A reasonably common

(but by no means the only) way of doing this might be at a

command-line, as this bypasses possible errors introduced by the

web server process itself. All you are doing is checking that the

basic code does what it says on the tin.

Note that for complicated systems, each unit might be a system in its

own right with sub-units. The division between system and unit tests in

such a case is a little hazy.

System Testing

Once you have all your units behaving as expected, you need to string

them together into a system, and test it in a semi-real environment,

which is only different from the way it will finally operate in that

you're not working with real users and live data.

Integration Testing

As eBusinesses become more complicated, there is a growing need for

the systems you produce to be integrated with other systems, like

the financial reporting system, the logistics system, the customer

database and so on.

The purpose of integration testing is to ensure that your system's

inputs from and outputs to the other systems are as expected. This

means that you will need to ensure that test data fed between the

systems is not going to be mistaken for live data. That said, at

some point you will need to put a real transaction through your

test system as an end-to-end test. A useful (and

popular with developers) way of doing this is giving the team working

on the site an allowance to spend on the site as 'friendly orders',

in return for reporting back any customer-facing inconsistencies in

the entire process.

Volume Testing

Far too often, an eBusiness is a victim of its own success. From

target="_foo" title="Launches in a new window">the Slashdot effect to

title="Cahoot offered 0% interest on the 1st 50,000 credit cards they issued. You couldn't access their site for a week after launch. Launches in a new window">sheer stupidity of the Marketing department, if your system won't

handle the loads put on it by users, you are going to lose both face

and money. Larger eRetailers are now building their systems to handle

over a thousand simultaneous users. While you may not be in that league,

you need to simulate the loads you anticipate, plus leaving enough

headroom for traffic growth. Get it wrong, and you may be facing

title="They launched their telesales in Summer 2000, but the web site didn't go live until December 2000, because their volume testing failed. Launches in a new window.">a

launch delay of months

Regression Testing

Unless you are spectacularly

, your testing will highlight errors in your system. And there's

a better than average chance that fixing those errors will introduce new

errors. Regression testing is a matter of going back over your previous

tests to ensure that:

  1. The bug you previously found has been fixed

  2. No new bugs have been introduced.

If you are producing release notes for each patch, it should be fairly easy

to track down the cause of new errors introduced with a patch.

The outcome of Regression is the inevitability that testing is an

iterative discipline - you will need to continue to

test, fix and regress until you have a system which meets the requirements.

User Acceptance Testing (UAT)

Once you have what appears to you to be a working system, which meets

all the requirements, the final piece of work you must undertake before

you can ask for your cheque is User Acceptance Testing. This is essentially

stepping through all the functionality with the client staff who are actually

going to use the system.

If your system fails UAT, yet meets the paper requirements, then you have

an issue with your requirements documentation. You will need to resolve this

with the client - has there been scope changes since the requirements doc

was signed off? - before you can justifiably ask the client to sign off

all your work and pay you.

Report Errors and Fix

Once your testing has highlighted issues with the system,

you need a process to ensure that each one is prioritised,

diagnosed and fixed.

A common approach is to have a central database which logs

each new error, and captures the following information:

  • An ID number

  • Status (new, in progress or resolved)

  • Priority:

    1. Red (ie causes non-functionality in the system.

      Must get fixed before go-live).

      I've also seen this subdivided into "Red" and

      "Mother of Red".

    2. Amber (ie causes interference to user tasks. Should

      get fixed before go-live).

    3. Green (ie causes annoyance to users. Will get fixed if there is

      time before go-live).

  • Patch ID which will resolve (or has resolved) the error

  • An owner - a named individual who will take responsibility for

    ensuring that the fix happens. This need not be the person who actually fixes it.

  • A detailed description of the error, including any error messages,

    and screenshots where appropriate.

On each update of an error report, you should record an audit trail, outlining

what's been changed, who's changed it and when.

More info: The Mythical Man Month, Fred Brooks.

Martin Burns has been doing this stuff since Netscape 1.0 days. Starting with the communication ends that online media support, he moved back through design, HTML and server-side code. Then he got into running the whole show. These days he's working for these people as a Project Manager, and still thinks (nearly 6 years on) it's a hell of a lot better than working for a dot-com. In his Copious Free Time™, he helps out running a Cloth Nappies online store.

Amongst his favourite things is ZopeDrupal, which he uses to run his personal site. He's starting to (re)gain a sneaking regard for ECMAscript since the arrival of unobtrusive scripting.

He's been a member of since the very early days, a board member, a president, a writer and even contributed a modest amount of template code for the current site. Above all, he likes to do things because it knowingly chooses to do so, rather than randomly stumbling into them. He's also one of the boys and girls who beervolts in the UK, although the arrival of small children in his life have knocked the frequency for 6.

Most likely to ask: Why would a client pay you to do that?

Least likely to ask: Why isn't that navigation frame in Flash?

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