<s>
Hamcrest	B-Language
is	O
a	O
framework	O
that	O
assists	O
writing	O
software	O
tests	O
in	O
the	O
Java	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
It	O
supports	O
creating	O
customized	O
assertion	O
matchers	O
( 	O
 '	O
Hamcrest	B-Language
 '	O
is	O
an	O
anagram	O
of	O
'	O
matchers	O
 '	O
)	O
,	O
allowing	O
match	O
rules	O
to	O
be	O
defined	O
declaratively	B-Language
.	O
</s>
<s>
These	O
matchers	O
have	O
uses	O
in	O
unit	O
testing	O
frameworks	O
such	O
as	O
JUnit	B-Language
and	O
jMock	O
.	O
</s>
<s>
Hamcrest	B-Language
has	O
been	O
included	O
in	O
JUnit	B-Language
4	O
since	O
2012	O
,	O
</s>
<s>
but	O
was	O
omitted	O
from	O
JUnit	B-Language
5	O
in	O
2017	O
.	O
</s>
<s>
Hamcrest	B-Language
has	O
been	O
ported	O
to	O
C++	B-Language
,	O
C#	B-Application
,	O
Objective-C	B-Language
,	O
Python	B-Language
,	O
ActionScript	B-Operating_System
3	I-Operating_System
,	O
PHP	B-Application
,	O
JavaScript	B-Language
,	O
Erlang	B-Operating_System
,	O
R	B-Language
,	O
Rust	B-Application
,	O
and	O
Swift	B-Application
.	O
</s>
<s>
So	O
"	O
third	O
generation	O
"	O
unit	O
test	O
frameworks	O
use	O
a	O
library	O
such	O
as	O
Hamcrest	B-Language
to	O
support	O
an	O
'	O
assert_that	O
 '	O
operator	O
that	O
can	O
be	O
combined	O
with	O
'	O
matcher	O
 '	O
objects	O
,	O
leading	O
to	O
syntax	O
like	O
this	O
:	O
</s>
<s>
This	O
results	O
in	O
a	O
rich	O
matcher	O
language	O
which	O
allows	O
complex	O
assertions	O
over	O
collections	O
to	O
be	O
written	O
in	O
a	O
declarative	B-Language
style	O
rather	O
than	O
a	O
procedural	O
style	O
.	O
</s>
