<s>
In	O
advanced	O
polymorphism	O
computer	O
science	O
,	O
test	B-General_Concept
stubs	I-General_Concept
are	O
programs	O
that	O
simulate	O
the	O
behaviours	O
of	O
software	O
components	O
(	O
or	O
modules	O
)	O
that	O
a	O
module	O
undergoing	O
tests	O
depends	O
on	O
.	O
</s>
<s>
Test	B-General_Concept
stubs	I-General_Concept
provide	O
canned	O
answers	O
to	O
calls	O
made	O
during	O
the	O
test	O
,	O
usually	O
not	O
responding	O
at	O
all	O
to	O
anything	O
outside	O
what	O
's	O
programmed	O
in	O
for	O
the	O
test	O
.	O
</s>
<s>
Stubs	B-Operating_System
are	O
computer	O
programs	O
that	O
act	O
as	O
temporary	O
replacement	O
for	O
a	O
called	O
basin	O
module	O
and	O
give	O
the	O
same	O
output	O
as	O
the	O
actual	O
product	O
or	O
software	O
.	O
</s>
<s>
This	O
would	O
be	O
a	O
test	B-General_Concept
stub	I-General_Concept
.	O
</s>
<s>
Several	O
testing	O
frameworks	O
are	O
available	O
,	O
as	O
is	O
software	O
that	O
generates	O
test	B-General_Concept
stubs	I-General_Concept
based	O
on	O
existing	O
source	O
code	O
and	O
testing	O
requirements	O
.	O
</s>
<s>
Stubs	B-Operating_System
and	O
Drivers	O
are	O
two	O
types	O
of	O
test	O
harness	O
.	O
</s>
<s>
Stubs	B-Operating_System
and	O
drivers	O
both	O
are	O
dummy	O
modules	O
and	O
are	O
only	O
created	O
for	O
test	O
purposes	O
.	O
</s>
<s>
Stubs	B-Operating_System
are	O
used	O
in	O
top	O
down	O
testing	O
approach	O
,	O
when	O
one	O
has	O
the	O
major	O
module	O
ready	O
to	O
test	O
,	O
but	O
the	O
sub	O
modules	O
are	O
still	O
not	O
ready	O
yet	O
.	O
</s>
<s>
So	O
in	O
a	O
simple	O
language	O
stubs	B-Operating_System
are	O
"	O
called	O
"	O
programs	O
,	O
which	O
are	O
called	O
in	O
to	O
test	O
the	O
major	O
module	O
's	O
functionality	O
.	O
</s>
<s>
These	O
dummy	O
pieces	O
of	O
code	O
are	O
the	O
stubs	B-Operating_System
.	O
</s>
