I would like to test that my function raises an Exception when trying to open a file that does not exist.

Here is my code for the function 

```
import os

def open_files(path_1, path_2):

    """Raises an Exception in case a file
    does not exists."""

    can_open_1 = os.path.exists(path_1)
    can_open_2 = os.path.exists(path_2)

    if can_open_1 or can_open_2 == False:
        raise Exception("Files do not exist")

```

and here for the test:

```
import unittest
import sys
sys.path.append(".")
import open_files

class TestOpenFiles(unittest.TestCase):

    def test_open_files(self):

        some_cool_exception = Exception("Files do not exist")
        self.assertRaises(some_cool_exception, open_files.open_files("maracana.tif", "carlitos.tif"))

if __name__ == "__main__":
    unittest.main()

```

I read that post: 
[object has no attribute 'assertEqual'](https://stackoverflow.com/questions/42859577/object-has-no-attribute-assertequal)
and I implemented the way that Exceptions can be tested using the unittest module in Python. 
I don't know why I still receive this error message when running the test via

```
python -m unittest test_open_files 

```

Error: 

```
test_open_files (test_open_files.TestOpenFiles) ... ERROR

---------------------------------------------------------
---------------------------------------------------------

Traceback (most recent call last):
    File "D:\Share\__Python_Development\88_Cloud_Detection\test_open_files.py", line 12, in test_open_files self.assertRaises(some_cool_exception, open_files.open_files("maracana.tif", "carlitos.tif")) 
    File "D:\Share\__Python_Development\88_Cloud_Detection\open_files.py", line 12, in open_files
    raise Exception("Files do not exist")
Exception: Files do not exist

------------------------------------------------------------------------------------
Ran 1 test in 0.0000x

FAILED (errors=1)

```

I cannot get information from the test run, which could help me to figure out to set a correct test for an exception.