Nosetests

[Roy Smith]

In article <b428f41a-cad9-4223-87a2-9cc602681f60 at googlegroups.com>,
 melwin9 at gmail.com wrote:

> Initially I was shown pexpect, leaving that there, Can i make up 5 tests? I 
> tried tests two different ways and no luck. What am I supposed to be writing 
> up when I do a test and is there a particular way I can/should be referencing 
> it back to its main file?

I'm not sure I understand your question.  Are you asking:

Q1: "What tests should I be writing?"

or

Q2: "Once I know what I want to test, how do I implement those tests?"

I'm guessing Q1, so that's what I'm going to base the rest of this post 
on.  Before you cat write a test, you have to understand what your code 
is supposed to do.  So, for example, let's say the specification for 
your program runs something like this:

When you run the program, it will print, "I have chosen a number from 
1-10", and then it will print, "Guess a number: ".  It will then wait 
for input.  When you type an integer, it will print either, "That's too 
high.", "That's too low.", or "That's right!".

Now, let's look at one of your tests:

    def test_guessing_hi_low_4(self):

        # Conversation assuming number is 4
        child = pe.spawn('python guess.py')
        child.expect(self.intro,timeout=5)
        child.expect(self.request,timeout=5)
        child.sendline('5')
        child.expect(self.responseHigh,timeout=5)
        child.sendline('3')
        child.expect(self.responseLow,timeout=5)
        child.sendline('4')
        child.expect(self.responseCorrect,timeout=5)
        child.expect(self.goodbye,timeout=5)

It looks pretty reasonable up to the point where you do:

        child.sendline('5')
        child.expect(self.responseHigh,timeout=5)

The problem is, you don't know what number it picked, so you can't 
predict what response it will have to an input of 5.  This goes back to 
what I was saying earlier.  You need some way to set the game to a known 
state, so you can test its responses, in that state, to various inputs.

If you're going to stick with the pexpect interface, then maybe you need 
a command line argument to override the random number generator and set 
the game to a specific number.  So, you can run:

$ python guess.py --test 4

and now you know the number it has picked is 4.  If you send it 5, it 
should tell you too high.  If you send it 3, it should tell you too low.  
And so on.

This is standard procedure in all kinds of testing.  You need some way 
to set the system being tested to a known state.  Then (and only then) 
can you apply various inputs and observe what outputs you get.  This is 
true of hardware was well.  Integrated circuits often have a "test 
mode", where you can set the internal state of the chip to some known 
configuration before you perform a test.