Hi,

Trying to get my head around Unit Testing (and Python) and I've come across a strange problem when adding some tests to the example from pyunit-1.4.1\doc\PyUnit.html.

class Widget: def __init__(self, widgetname, size=(50,50)): self.name = widgetname self._size = size def func(self): return 4 def name(self): return self.name

class WidgetTestCase(unittest.TestCase): def setUp(self): self.widget = Widget("The widget") def testFunc(self): assert self.widget.func() == 3, 'Invalid value' def testName(self): assert self.widget.name() == "The widget", "Invalid name"

I'm getting the error "TypeError: 'str' object is not callable" when I run my test suite. It's complaining about the last line of code. However, if I take the function call brackets off (assert self.widget.name == "The widget", "Invalid name") it works fine. I expected it to work like the func() example above it.

I suspect you may have copied the example incorrectly, but what is happening is this: You have defined a class Widget with a method called 'name', but in your __init__ method you are assigning to an attribute also called 'name'. The attribute is stored in the instance and this hides the method, so when you access self.widget.name you are retrieving the string rather than the method. When you attempt to call the string retrieved by self.widget.name you get an error telling you that you cannot call a string. Remember that functions and methods are first class objects in Python, so for example the test: assert self.widget.func() == 3, 'Invalid value' could equally well be written as: x = self.widget.func assert x() == 3, 'Invalid value' The compiler does not, and indeed cannot, make a distinction between accessing an attribute and calling a method: you could have assigned a function or some other callable to self.widget.name by the time it tries to access it. I hope this help.

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