AttributeError¶

AttributeError is raised when there is a reference to a name that is NOT in an object that exists.

An attribute is a name for something that belongs to an object, for example, a human being has attributes like height, weight, sex and color. They are also known as properties

requirements¶

I open a terminal to run makePythonTdd.sh with attribute_error as the name of the project
```
./makePythonTdd.sh attribute_error
```
on Windows without Windows Subsystem Linux use makePythonTdd.ps1 instead of makePythonTdd.sh
```
./makePythonTdd.ps1 attribute_error
```
it makes the folders and files that are needed, installs packages, runs the first test, and the terminal shows AssertionError
```
E       AssertionError: True is not false

tests/test_attribute_error.py:7: AssertionError
```
I hold ctrl (windows/linux) or option (mac) on the keyboard and use the mouse to click on tests/test_attribute_error.py:7 to open it in the editor
then I change True to False to make the test pass
```
7        self.assertFalse(False)
```
I change the name of the class to match the CapWords format
```
4class TestAttributeError(unittest.TestCase):
```

test_attribute_error_w_variables¶

red: make it fail¶

I add an import statement at the top of test_attribute_error.py
```
1import unittest
2import src.attribute_error
```

I change test_failure to test_attribute_error_w_variables

class TestAttributeError(unittest.TestCase):

    def test_attribute_error_w_variables(self):
        src.attribute_error.variable_00

# Exceptions Encountered

I think of src.attribute_error.variable_00 as an address for variable_00 in attribute_error.py which is in the src folder. Since the file is empty, the variable is not in it.

The terminal shows AttributeError

AttributeError: module 'src.attribute_error' has no attribute 'variable_00'

I add the error to the list of Exceptions encountered in test_attribute_error.py
```
11# Exceptions Encountered
12# AssertionError
13# AttributeError
```

green: make it pass¶

I click on attribute_error.py in the src folder to open it in the editor of my Integrated Development Environment (IDE), then I add a name
```
1variable_00
```
the terminal shows NameError
```
NameError: name 'variable_00' is not defined
```

I add it to the list of Exceptions encountered in test_attribute_error.py

# Exceptions Encountered
# AssertionError
# AttributeError
# NameError

I point variable_00 to None in attribute_error.py
```
1variable_00 = None
```
the test passes. variable_00 is now an attribute/property of attribute_error.py which is in the src folder and I can reach it by using src.attribute_error.variable_00

refactor: make it better¶

I do the same test a few more times as a drill in test_attribute_error.py

    def test_attribute_error_w_variables(self):
        src.attribute_error.variable_00
        src.attribute_error.variable_01

AttributeError¶

requirements¶

test_attribute_error_w_variables¶

red: make it fail¶

green: make it pass¶

refactor: make it better¶

test_attribute_error_w_functions¶

red: make it fail¶

green: make it pass¶

refactor: make it better¶

test_attribute_error_w_class_attributes¶

red: make it fail¶

green: make it pass¶

refactor: make it better¶

test_attribute_error_w_class_methods¶

red: make it fail¶

green: make it pass¶

refactor: make it better¶

review¶