...
Testing
...
is
...
a
...
complex
...
subject
...
that
...
sometimes
...
is
...
overlooked
...
during
...
the
...
development
...
of
...
a
...
software
...
application,
...
but
...
is
...
crucial
...
to
...
its
...
success.
...
In
...
this
...
document
...
I
...
want
...
to
...
do
...
a
...
quick
...
introduction
...
to
...
testing
...
of
...
applications,
...
so
...
users
...
with
...
less
...
experience
...
in
...
the
...
subject
...
can
...
understand
...
the
...
aims
...
and
...
benefits
...
as
...
well
...
as
...
how
...
we
...
achieve
...
those
...
aims.
...
Please
...
feel
...
free
...
to
...
add
...
any
...
correction
...
or
...
extra
...
information
...
you
...
feel
...
relevant.
...
Also,
...
my
...
native
...
language
...
is
...
not
...
English,
...
so
...
I
...
apologise
...
if
...
you
...
find
...
some
...
parts
...
of
...
the
...
text
...
hard
...
to
...
understand.
...
Feel
...
free
...
to
...
advise
...
me
...
a
...
correction.
...
| Wiki Markup |
|---|
You can also find a more detailed reference in Wikipedia \[[http://en.wikipedia.org/wiki/Software_testing|http://en.wikipedia.org/wiki/Software_testing]\] |
...
Please
...
note
...
in
...
this
...
document
...
when
...
referring
...
to
...
DSpace
...
I'm
...
talking
...
about
...
the
...
vanilla
...
DSpace
...
code.
...
Customisations
...
in
...
the
...
code
...
may
...
have
...
an
...
impact
...
on
...
what's
...
described
...
here.
...
What's
...
Testing
...
The
...
primary
...
purpose
...
for
...
testing
...
is
...
to
...
detect
...
software
...
failures
...
so
...
that
...
we
...
can
...
fix
...
them.
...
Simple
...
as
...
it
...
sounds,
...
it's
...
a
...
non-trivial
...
task
...
as
...
any
...
amount
...
of
...
testing
...
can't
...
guarantee
...
a
...
software
...
doesn't
...
fail,
...
only
...
that
...
it
...
fails
...
under
...
a
...
set
...
of
...
conditions
...
or
...
(when
...
we
...
fix
...
the
...
issue)
...
that
...
it
...
works
...
under
...
that
...
set
...
of
...
conditions.
...
As
...
you
...
can
...
deduce
...
from
...
the
...
previous
...
definition,
...
testing
...
is
...
not
...
only
...
a
...
matter
...
of
...
code,
...
but
...
also
...
of
...
the
...
environment
...
in
...
which
...
this
...
code
...
is
...
run.
...
That
...
means
...
that
...
testing
...
includes
...
examination
...
of
...
code
...
as
...
well
...
as
...
execution
...
of
...
that
...
code
...
in
...
various
...
environments
...
and
...
conditions
...
as
...
well
...
as
...
examining
...
the
...
aspects
...
of
...
code:
...
does
...
it
...
do
...
what
...
it
...
is
...
supposed
...
to
...
do
...
and
...
do
...
what
...
it
...
needs
...
to
...
do.
...
Types
...
of
...
Testing
...
Testing
...
has
...
many
...
approaches
...
that
...
try
...
to
...
cover
...
different
...
aspects
...
of
...
the
...
application,
...
to
...
reduce
...
the
...
possibility
...
of
...
a
...
user
...
finding
...
an
...
unknown
...
bug
...
as
...
much
...
as
...
possible.
...
Some
...
of
...
these
...
approaches
...
are:
...
- Functional
...
- Tests:
...
- these
...
- are
...
- tests
...
- which
...
- come
...
- from
...
- user-based
...
- use
...
- cases.
...
- Such
...
- as
...
- a
...
- user
...
- wants
...
- to
...
- search
...
- DSpace
...
- to
...
- find
...
- material
...
- and
...
- download
...
- a
...
- pdf.
...
- Or
...
- something
...
- more
...
- complex
...
- like
...
- a
...
- user
...
- wants
...
- to
...
- submit
...
- their
...
- thesis
...
- to
...
- DSpace
...
- and
...
- follow
...
- it
...
- through
...
- the
...
- approval
...
- process.
...
- These
...
- are
...
- stories
...
- about
...
- how
...
- users
...
- would
...
- preform
...
- tasks
...
- and
...
- cover
...
- a
...
- wide
...
- array
...
- of
...
- components
...
- within
...
- Dspace.
...
- Integration
...
- Tests:
...
- these
...
- tests
...
- work
...
- at
...
- the
...
- API
...
- level
...
- and
...
- test
...
- the
...
- interaction
...
- of
...
- components
...
- within
...
- the
...
- system.
...
- Some
...
- examples,
...
- placing
...
- an
...
- item
...
- into
...
- a
...
- collection,
...
- or
...
- creating
...
- a
...
- new
...
- metadata
...
- schema
...
- and
...
- adding
...
- some
...
- fields.
...
- Primarily
...
- these
...
- tests
...
- operate
...
- at
...
- the
...
- API
...
- level
...
- ignoring
...
- the
...
- interface
...
- components
...
- above
...
- it.
...
- Unit
...
- Tests:
...
- these
...
- are
...
- tests
...
- which
...
- test
...
- just
...
- how
...
- one
...
- object
...
- works.
...
- Typically
...
- test
...
- each
...
- method
...
- on
...
- an
...
- object
...
- for
...
- expected
...
- output
...
- in
...
- several
...
- situations.
...
- They
...
- are
...
- executed
...
- exclusively
...
- at
...
- the
...
- API
...
- level.
...
- Regression
...
- Testing:
...
- these
...
- are
...
- tests
...
- which
...
- focus
...
- on
...
- finding
...
- defects
...
- after
...
- a
...
- major
...
- code
...
- change.
...
- The
...
- aim
...
- is
...
- to
...
- detect
...
- if
...
- old
...
- bugs
...
- have
...
- resurfaced
...
- due
...
- to
...
- the
...
- changes,
...
- or
...
- if
...
- those
...
- changes
...
- have
...
- broken
...
- another
...
- component
...
- of
...
- the
...
- system.
...
- It's
...
- usually
...
- covered
...
- with
...
- the
...
- tests
...
- created
...
- for
...
- Unit
...
- Testing,
...
- Integration
...
- Testing
...
- and
...
- Functional
...
- Testing.
...
- Performance
...
- Tests:
...
- these
...
- are
...
- tests
...
- which
...
- test
...
- how
...
- the
...
- application
...
- behaves
...
- under
...
- heavy
...
- load,
...
- and
...
- how
...
- many
...
- users
...
- it
...
- can
...
- manage
...
- at
...
- a
...
- time.
...
- While
...
- the
...
- other
...
- types
...
- of
...
- tests
...
- mentioned
...
- are
...
- platform-independent,
...
- these
...
- tests
...
- depend
...
- on
...
- the
...
- hardware
...
- they
...
- are
...
- run
...
- and
...
- on
...
- the
...
- settings
...
- of
...
- components
...
- external
...
- to
...
- the
...
- application
...
- itself,
...
- like
...
- the
...
- database.
...
- They
...
- usually
...
- reproduce
...
- functional
...
- tests
...
- to
...
- simulate
...
- "real
...
- load"
...
- in
...
- the
...
- application.
...
- Manual
...
- Testing:
...
- these
...
- are
...
- tests
...
- run
...
- by
...
- humans
...
- on
...
- the
...
- application.
...
- Although
...
- slower
...
- and
...
- probably
...
- not
...
- so
...
- extensive,
...
- they
...
- can
...
- detect
...
- issues
...
- that
...
- other
...
- test
...
- may
...
- fail
...
- to
...
- recognise,
...
- like
...
- problems
...
- with
...
- the
...
- layout,
...
- graphic
...
- glitches
...
- or
...
- similar.
...
How
...
to
...
Work
...
with
...
Tests
...
Ideally
...
all
...
tests,
...
when
...
possible,
...
have
...
to
...
be
...
run
...
automatically
...
and
...
after
...
every
...
code
...
change,
...
so
...
no
...
code
...
that
...
doesn't
...
pass
...
the
...
existing
...
set
...
of
...
tests
...
is
...
committed
...
to
...
the
...
repository.
...
Also
...
ideally
...
you
...
should
...
do
...
Test
...
Driven
...
Development
...
(explained
...
later).
...
To
...
this
...
aim,
...
tests
...
should
...
be
...
run
...
in
...
the
...
compile
...
cycle,
...
that
...
way
...
the
...
developer
...
doesn't
...
need
...
to
...
remember
...
to
...
run
...
them.
...
The
...
downside
...
of
...
this
...
approach
...
is
...
longer
...
build
...
cycles
...
as
...
the
...
test
...
are
...
run,
...
but
...
the
...
benefits
...
of
...
running
...
the
...
tests
...
are
...
worth
...
this
...
delay.
...
To
...
compensate
...
for
...
this
...
a
...
good
...
alternative
...
is
...
to
...
build
...
a
...
Continuous
...
Integration
...
system
...
(like
...
Hudson)
...
where
...
the
...
tests
...
are
...
run
...
constantly.
...
That
...
way
...
the
...
developers
...
only
...
need
...
to
...
run
...
the
...
tests
...
before
...
submitting
...
the
...
changes,
...
which
...
saves
...
time
...
in
...
the
...
compilation
...
process,
...
and
...
Hudson
...
will
...
do
...
an
...
extra
...
validation
...
to
...
ensure
...
the
...
commits
...
don't
...
break
...
the
...
build.
...
All
...
tests
...
require
...
extensive
...
maintenance.
...
Every
...
time
...
a
...
new
...
bug
...
is
...
discovered,
...
a
...
test
...
has
...
to
...
be
...
created
...
to
...
reproduce
...
it
...
before
...
solving
...
it.
...
This
...
serves
...
two
...
purposes:
...
on
...
one
...
hand,
...
we
...
ensure
...
we
...
understand
...
the
...
bug
...
and
...
why
...
it
...
happens.
...
On
...
the
...
other
...
hand,
...
we
...
add
...
this
...
test
...
to
...
the
...
existing
...
tests,
...
which
...
enables
...
regression
...
testing
...
and
...
(in
...
the
...
long
...
term)
...
increases
...
the
...
stability
...
and
...
robustness
...
of
...
the
...
application.
...
How
...
Hard
...
is
...
to
...
Create
...
Tests
...
Creating
...
tests
...
is
...
not
...
too
...
complex
...
in
...
general,
...
although
...
for
...
certain
...
types
...
of
...
test
...
some
...
technical
...
knowledge
...
is
...
required.
...
The
...
simplest
...
tests
...
to
...
create
...
are
...
probably
...
(and
...
depending
...
on
...
our
...
approach
...
to
...
them)
...
Functional
...
Tests.
...
Most
...
of
...
those
...
tests
...
are
...
based
...
on
...
UI
...
interaction
...
and
...
tools
...
like
...
Selenium
...
allows
...
us
...
to
...
record
...
the
...
actions
...
we
...
are
...
doing
...
on
...
the
...
page
...
to
...
reproduce
...
them
...
later.
...
This
...
lets
...
a
...
non-technical
...
user,
...
with
...
a
...
minimal
...
knowledge
...
of
...
the
...
tools,
...
to
...
create
...
a
...
set
...
of
...
tests
...
for
...
his
...
or
...
her
...
repository.
...
Integration
...
Tests
...
and
...
Unit
...
Tests
...
require
...
someone
...
with
...
a
...
deeper
...
understanding
...
of
...
DSpace
...
API
...
as
...
they
...
work
...
directly
...
with
...
it.
...
That
...
means
...
only
...
developers
...
will
...
be
...
able
...
to
...
create
...
these
...
kind
...
of
...
tests.
...
One
...
issue
...
we
...
may
...
find
...
when
...
creating
...
Unit
...
Tests
...
is
...
that
...
the
...
code
...
is
...
not
...
testable.
...
In
...
this
...
case,
...
a
...
refactoring
...
of
...
the
...
code
...
may
...
be
...
advised,
...
as
...
lack
...
of
...
testability
...
may
...
point
...
to
...
design
...
or
...
coding
...
issues.
...
Performance
...
Tests
...
are
...
probably
...
the
...
hardest
...
to
...
create,
...
as
...
we
...
have
...
to
...
account
...
for
...
several
...
variables
...
(hardware,
...
settings)
...
besides
...
running
...
the
...
testing
...
itself,
...
and
...
after
...
that
...
we
...
have
...
to
...
understand
...
and
...
interpret
...
the
...
data
...
the
...
correct
...
way.
...
Testability
We understand Testability as a set of practices that makes the creation of tests (mainly Unit and Integration Tests) easier, and at the same time they are generally good practices when coding.
A Testable code, in general, uses injection of dependencies in the constructor, avoids global state (static variables) and follows the Law of Demeter. Following this simple principles our code quality will improve and we will reduce the effort required to create tests.
The Law of Demeter is a guideline for software development that promotes loose coupling. It can be stated as "use only one dot", referring to the fact that if we need access to an object we should get the object in the constructor, not through a method call to another object. That is:
b.getValue() is better than a.getB().getValue()
...
...
...
has
...
published
...
a
...
tool,
...
Testability
...
Explorer,
...
to
...
determine
...
how
...
testable
...
is
...
an
...
application.
...
You
...
can
...
find
...
it
...
at
...
http://code.google.com/p/testability-explorer/
...
Test Driven Development
Test-driven
...
development
...
(TDD)
...
is
...
a
...
development
...
technique
...
that
...
relies
...
on
...
the
...
repetition
...
of
...
a
...
very
...
short
...
development
...
cycle:
...
first
...
the
...
developer
...
writes
...
a
...
failing
...
automated
...
test
...
case
...
that
...
defines
...
a
...
desired
...
improvement
...
or
...
new
...
function,
...
then
...
produces
...
code
...
to
...
pass
...
that
...
test
...
and
...
finally
...
refactors
...
the
...
new
...
code
...
to
...
fit
...
the
...
application.
...
The
...
advantage
...
of
...
this
...
procedure
...
is
...
that
...
we
...
develop
...
the
...
tests
...
(mainly
...
Unit
...
Tests
...
and
...
Integration
...
Tests,
...
but
...
also
...
Functional
...
Tests
...
when
...
required)
...
as
...
we
...
develop
...
the
...
code.
...
Having
...
to
...
create
...
the
...
test
...
first
...
makes
...
us
...
think
...
about
...
the
...
problem
...
deeper,
...
ensuring
...
we
...
are
...
aware
...
of
...
all
...
the
...
requirements.
...
In
...
short,
...
this
...
leads
...
to
...
simpler
...
code
...
which
...
will
...
result
...
easier
...
to
...
maintain
...
and
...
that
...
already
...
has
...
tests
...
to
...
validate
...
it.
...
| Wiki Markup |
|---|
You can find more details at Wikipedia \[[http://en.wikipedia.org/wiki/Test-driven_development|http://en.wikipedia.org/wiki/Test-driven_development] \] |
...
Thanks
This page has been created with help from Stuart Lewis, Scott Phillips and Gareth Waller. I want to thank them all for their comments. Some information has been taken from Wikipedia to make the text more complete. I'm to blame for errors in the text.
Feel free to contribute to this page!