Some Python decorators
October 5th, 2009 by admin
import should
@ should.give ((5,2), 7)
@ should.give (( “aa”, “bbb”), “aabbb”)
@ should.give (([1], [2,3]), [1,2,3]),
@ should.give ((1,1), 1) # test
def add (a, b):
return a + b
@ should.throw ((1,0), Exception)
@ should.throw ((5,0), ZeroDivisionError)
@ should.throw ((5,0), TypeError) # test
@ should.throw ((5,1), TypeError) # test
def div (a, b):
return a / b
> pythonw-u “should.py”
[!] Add (1, 1) should give 1, but got 2.
[!] Div (5, 1) should raise TypeError, but raised nothing.
[!] Div (5, 0) should raise TypeError, but raised ZeroDivisionError.
> Exit code: 0
The idea is to describe the test cases to function as a decorator. Then they will perform a dual function:
Testing (automatic check at startup code after the change)
documentation (examples of functions)
Implementation:
# File: should.py
def render_func_args (f, args):
return ‘% s (% s)’% (f.__name__, ‘,’. join (map (repr, args)))
def _inform (msg):
print’[!]‘, msg
def should (args, expected):
def check (f):
val = f (* args)
if val! = expected:
_inform ( ‘% s should give% s, but got% s.’% \
(render_func_args (f, args), repr (expected), repr (val)))
def decor (f):
check (f)
return f
return decor
def should_raise (args, ExcptClass):
def check (f):
excpt = None
try:
f (* args)
except Exception, ex:
excpt = ex
if excpt == None:
_inform ( “% s should raise% s, but raised nothing.”% \
(render_func_args (f, args), ExcptClass.__name__))
elif not isinstance (excpt, ExcptClass):
_inform ( “% s should raise% s, but raised% s.”% \
(render_func_args (f, args), ExcptClass.__name__, excpt.__class__.__name__))
def decor (f):
check (f)
return f
return decor
throw = should_raise
give = should
if __name__ ==’__ main__ ‘:
import should
@ should.give ((5,2), 7)
@ should.give (( “aa”, “bbb”), “aabbb”)
@ should.give (([1], [2,3]), [1,2,3]),
@ should.give ((1,1), 1) # test
def add (a, b):
return a + b
@ should.throw ((1,0), Exception)
@ should.throw ((5,0), ZeroDivisionError)
@ should.throw ((5,0), TypeError) # test
@ should.throw ((5,1), TypeError) # test
def div (a, b):
return a / b
* This source code was highlighted with Source Code Highlighter.
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