A new syntax for writing tests
in [Python]
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From: Jonathan Fine on 4 Aug 2010 16:15 Hi I just discovered today a new syntax for writing tests. The basic idea is to write a function that contains some statements, and run it via a decorator. I wonder if anyone had seen this pattern before, and how you feel about it. For myself, I quite like it. Let's suppose we want to test this trivial (of course) class. class Adder(object): def __init__(self): self.value = 0 def plus(self, delta): self.value += delta The test the class you need a runner. In this case it is quite simple. def runner(script, expect): '''Create an adder, run script, expect value.''' adder = Adder() script(adder) return adder.value We can now create (and run if we wish) a test. To do this we write @testit(runner, 4) def whatever(a): '''Two plus two is four.''' a.plus(2) a.plus(2) Depending on the exact value of the testit decorator (which in the end is up to you) we can store the test, or execute it immediately, or do something else. The simplest implementation prints: OK: Two plus two is four. for this passing test, and Fail: Two plus four is five. expect 5 actual 6 for a test that fails. Here is the testit decorator used to produce the above output: def testit(runner, expect): '''Test statements decorator.''' def next(script): actual = runner(script, expect) if actual == expect: print 'OK:', script.__doc__ else: print 'Fail:', script.__doc__ print ' expect', expect print ' actual', actual return next You can pick this code, for at least the next 30 days, at http://dpaste.com/hold/225056/ For me the key benefit is that writing the test is really easy. Here's a test I wrote earlier today. @testit(runner, '''<a att="value"><b/></a>''') def whatever(tb): tb.start('a', {'att': 'value'}) tb.start('b') tb.end('b') tb.end('a') If the test has a set-up and tear-down, this can be handled in the runner, as can the test script raising an expected or unexpected exception. -- Jonathan
From: Jean-Michel Pichavant on 5 Aug 2010 05:17 Jonathan Fine wrote: > Hi > > I just discovered today a new syntax for writing tests. The basic > idea is to write a function that contains some statements, and run it > via a decorator. I wonder if anyone had seen this pattern before, and > how you feel about it. For myself, I quite like it. > > Let's suppose we want to test this trivial (of course) class. > class Adder(object): > > def __init__(self): > self.value = 0 > > def plus(self, delta): > self.value += delta > > The test the class you need a runner. In this case it is quite simple. > > def runner(script, expect): > '''Create an adder, run script, expect value.''' > > adder = Adder() > script(adder) > return adder.value > > We can now create (and run if we wish) a test. To do this we write > > @testit(runner, 4) > def whatever(a): > '''Two plus two is four.''' > > a.plus(2) > a.plus(2) > > Depending on the exact value of the testit decorator (which in the end > is up to you) we can store the test, or execute it immediately, or do > something else. > > The simplest implementation prints: > OK: Two plus two is four. > for this passing test, and > Fail: Two plus four is five. > expect 5 > actual 6 > for a test that fails. > > Here is the testit decorator used to produce the above output: > > def testit(runner, expect): > '''Test statements decorator.''' > > def next(script): > actual = runner(script, expect) > if actual == expect: > print 'OK:', script.__doc__ > else: > print 'Fail:', script.__doc__ > print ' expect', expect > print ' actual', actual > > return next > > > You can pick this code, for at least the next 30 days, at > http://dpaste.com/hold/225056/ > > For me the key benefit is that writing the test is really easy. > Here's a test I wrote earlier today. > > @testit(runner, '''<a att="value"><b/></a>''') > def whatever(tb): > tb.start('a', {'att': 'value'}) > tb.start('b') > tb.end('b') > tb.end('a') > > If the test has a set-up and tear-down, this can be handled in the > runner, as can the test script raising an expected or unexpected > exception. > Hi, "The unittest module provides a rich set of tools for constructing and running tests. This section demonstrates that a small subset of the tools suffice to meet the needs of most users." source http://docs.python.org/library/unittest.html As you can see, a much more featured test framework already exists. There's nothing wrong in a new test framework, but it has to be better than the existing one in some situations. JM
From: jfine on 5 Aug 2010 09:07 On 5 Aug, 10:17, Jean-Michel Pichavant <jeanmic...(a)sequans.com> wrote: > Jonathan Fine wrote: > > Hi > > > I just discovered today anewsyntaxfor writing tests. The basic > > idea is to write a function that contains some statements, and run it > > via a decorator. I wonder if anyone had seen this pattern before, and > > how you feel about it. For myself, I quite like it. > > > Let's suppose we want to test this trivial (of course) class. > > class Adder(object): > > > def __init__(self): > > self.value = 0 > > > def plus(self, delta): > > self.value += delta > > > The test the class you need a runner. In this case it is quite simple. > > > def runner(script, expect): > > '''Create an adder, run script, expect value.''' > > > adder = Adder() > > script(adder) > > return adder.value > > > We can now create (and run if we wish) a test. To do this we write > > > @testit(runner, 4) > > def whatever(a): > > '''Two plus two is four.''' > > > a.plus(2) > > a.plus(2) > > > Depending on the exact value of the testit decorator (which in the end > > is up to you) we can store the test, or execute it immediately, or do > > something else. > > > The simplest implementation prints: > > OK: Two plus two is four. > > for this passing test, and > > Fail: Two plus four is five. > > expect 5 > > actual 6 > > for a test that fails. > > > Here is the testit decorator used to produce the above output: > > > def testit(runner, expect): > > '''Test statements decorator.''' > > > def next(script): > > actual = runner(script, expect) > > if actual == expect: > > print 'OK:', script.__doc__ > > else: > > print 'Fail:', script.__doc__ > > print ' expect', expect > > print ' actual', actual > > > return next > > > You can pick this code, for at least the next 30 days, at > > http://dpaste.com/hold/225056/ > > > For me the key benefit is that writing the test is really easy. > > Here's a test I wrote earlier today. > > > @testit(runner, '''<a att="value"><b/></a>''') > > def whatever(tb): > > tb.start('a', {'att': 'value'}) > > tb.start('b') > > tb.end('b') > > tb.end('a') > > > If the test has a set-up and tear-down, this can be handled in the > > runner, as can the test script raising an expected or unexpected > > exception. > > Hi, > > "The unittest module provides a rich set of tools for constructing and > running tests. This section demonstrates that a small subset of the > tools suffice to meet the needs of most users." > > sourcehttp://docs.python.org/library/unittest.html > > As you can see, a much more featured test framework already exists. > > There's nothing wrong in anewtest framework, but it has to be better > than the existing one in some situations. Chalk and cheese. My concern is to make tests easy to write, and that is something that unittest is, in my view, not good at. It is, as you say, a *test framework*. I've not written a test framework. I've found what seems to be a new *syntax* for writing tests. Tests written in the new syntax can be run in the unittest (or any other) framework. -- Jonathan
From: Jean-Michel Pichavant on 5 Aug 2010 09:52 jfine wrote: > On 5 Aug, 10:17, Jean-Michel Pichavant <jeanmic...(a)sequans.com> wrote: > >> Jonathan Fine wrote: >> >>> Hi >>> >>> I just discovered today anewsyntaxfor writing tests. The basic >>> idea is to write a function that contains some statements, and run it >>> via a decorator. I wonder if anyone had seen this pattern before, and >>> how you feel about it. For myself, I quite like it. >>> >>> Let's suppose we want to test this trivial (of course) class. >>> class Adder(object): >>> >>> def __init__(self): >>> self.value = 0 >>> >>> def plus(self, delta): >>> self.value += delta >>> >>> The test the class you need a runner. In this case it is quite simple. >>> >>> def runner(script, expect): >>> '''Create an adder, run script, expect value.''' >>> >>> adder = Adder() >>> script(adder) >>> return adder.value >>> >>> We can now create (and run if we wish) a test. To do this we write >>> >>> @testit(runner, 4) >>> def whatever(a): >>> '''Two plus two is four.''' >>> >>> a.plus(2) >>> a.plus(2) >>> >>> Depending on the exact value of the testit decorator (which in the end >>> is up to you) we can store the test, or execute it immediately, or do >>> something else. >>> >>> The simplest implementation prints: >>> OK: Two plus two is four. >>> for this passing test, and >>> Fail: Two plus four is five. >>> expect 5 >>> actual 6 >>> for a test that fails. >>> >>> Here is the testit decorator used to produce the above output: >>> >>> def testit(runner, expect): >>> '''Test statements decorator.''' >>> >>> def next(script): >>> actual = runner(script, expect) >>> if actual == expect: >>> print 'OK:', script.__doc__ >>> else: >>> print 'Fail:', script.__doc__ >>> print ' expect', expect >>> print ' actual', actual >>> >>> return next >>> >>> You can pick this code, for at least the next 30 days, at >>> http://dpaste.com/hold/225056/ >>> >>> For me the key benefit is that writing the test is really easy. >>> Here's a test I wrote earlier today. >>> >>> @testit(runner, '''<a att="value"><b/></a>''') >>> def whatever(tb): >>> tb.start('a', {'att': 'value'}) >>> tb.start('b') >>> tb.end('b') >>> tb.end('a') >>> >>> If the test has a set-up and tear-down, this can be handled in the >>> runner, as can the test script raising an expected or unexpected >>> exception. >>> >> Hi, >> >> "The unittest module provides a rich set of tools for constructing and >> running tests. This section demonstrates that a small subset of the >> tools suffice to meet the needs of most users." >> >> sourcehttp://docs.python.org/library/unittest.html >> >> As you can see, a much more featured test framework already exists. >> >> There's nothing wrong in anewtest framework, but it has to be better >> than the existing one in some situations. >> > > Chalk and cheese. > > My concern is to make tests easy to write, and that is something that > unittest is, in my view, not good at. It is, as you say, a *test > framework*. > > I've not written a test framework. I've found what seems to be a new > *syntax* for writing tests. Tests written in the new syntax can be > run in the unittest (or any other) framework. > > -- > Jonathan > > Well, I never used unittest, but the given example in the doc is pretty much simple. I'm still scratching my head. JM PS : I think your usage of 'syntax' is inapropriate.
From: jfine on 5 Aug 2010 11:06 On 5 Aug, 14:52, Jean-Michel Pichavant <jeanmic...(a)sequans.com> wrote: > jfine wrote: > > On 5 Aug, 10:17, Jean-Michel Pichavant <jeanmic...(a)sequans.com> wrote: > > >> Jonathan Fine wrote: > > >>> Hi > > >>> I just discovered today anewsyntaxfor writing tests. The basic > >>> idea is to write a function that contains some statements, and run it > >>> via a decorator. I wonder if anyone had seen this pattern before, and > >>> how you feel about it. For myself, I quite like it. > > >>> Let's suppose we want to test this trivial (of course) class. > >>> class Adder(object): > > >>> def __init__(self): > >>> self.value = 0 > > >>> def plus(self, delta): > >>> self.value += delta > > >>> The test the class you need a runner. In this case it is quite simple. > > >>> def runner(script, expect): > >>> '''Create an adder, run script, expect value.''' > > >>> adder = Adder() > >>> script(adder) > >>> return adder.value > > >>> We can now create (and run if we wish) a test. To do this we write > > >>> @testit(runner, 4) > >>> def whatever(a): > >>> '''Two plus two is four.''' > > >>> a.plus(2) > >>> a.plus(2) > > >>> Depending on the exact value of the testit decorator (which in the end > >>> is up to you) we can store the test, or execute it immediately, or do > >>> something else. > > >>> The simplest implementation prints: > >>> OK: Two plus two is four. > >>> for this passing test, and > >>> Fail: Two plus four is five. > >>> expect 5 > >>> actual 6 > >>> for a test that fails. > > >>> Here is the testit decorator used to produce the above output: > > >>> def testit(runner, expect): > >>> '''Test statements decorator.''' > > >>> def next(script): > >>> actual = runner(script, expect) > >>> if actual == expect: > >>> print 'OK:', script.__doc__ > >>> else: > >>> print 'Fail:', script.__doc__ > >>> print ' expect', expect > >>> print ' actual', actual > > >>> return next > > >>> You can pick this code, for at least the next 30 days, at > >>> http://dpaste.com/hold/225056/ > > >>> For me the key benefit is that writing the test is really easy. > >>> Here's a test I wrote earlier today. > > >>> @testit(runner, '''<a att="value"><b/></a>''') > >>> def whatever(tb): > >>> tb.start('a', {'att': 'value'}) > >>> tb.start('b') > >>> tb.end('b') > >>> tb.end('a') > > >>> If the test has a set-up and tear-down, this can be handled in the > >>> runner, as can the test script raising an expected or unexpected > >>> exception. > > >> Hi, > > >> "The unittest module provides a rich set of tools for constructing and > >> running tests. This section demonstrates that a small subset of the > >> tools suffice to meet the needs of most users." > > >> sourcehttp://docs.python.org/library/unittest.html > > >> As you can see, a much more featured test framework already exists. > > >> There's nothing wrong in anewtest framework, but it has to be better > >> than the existing one in some situations. > > > Chalk and cheese. > > > My concern is to make tests easy to write, and that is something that > > unittest is, in my view, not good at. It is, as you say, a *test > > framework*. > > > I've not written a test framework. I've found what seems to be anew > > *syntax* for writing tests. Tests written in thenewsyntaxcan be > > run in the unittest (or any other) framework. > > > -- > > Jonathan > > Well, I never used unittest, but the given example in the doc is pretty > much simple. > I'm still scratching my head. I think you'd understand better if you used unittest. For example, try coding my test (with say 10 distinct tests of a class more complicated than Adder) using unittest. I think you'll see the point when you get to number 5. Here, for reference, is my complete code for one test. See how it scales. http://dpaste.com/hold/225056/ (available for at least 30 days). -- Jonathan
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