Test succeeds in Python interpreter, but unit test in command prompt fails

Question

I have the following things defined:

def test_groupEs(self):
    for in_list, out_list in self.groupEs_tests:
        self.assertEqual(linSol2.groupEs(in_list), out_list)

groupEs_tests = [
(['4.0x', '-', '2.0e', '-', '4'], ['4.0x', '-' '2.0e-4'])
]

(both in a unittest class)

def groupEs(list):
    for m in range(0, len(list)):
        if re.search('[Ee]\Z', list[m]) != None:
            x = list[m] + list[m+1] + list[m+2]
            list[m+1], list[m+2] = '', ''
            list[m] = x
    removeBlanks(list)
    return list

def removeBlanks(list): # Take empty elements out of the list
    p = len(list) - 1
    while p > -1:
        if list[p] == '':
            list[p:p+1] = []
        p -= 1

(both in the file linSol2.py)

When I import linSol2.py and run linSol2.groupEs in the Python interpreter, it works perfectly:

>>> x = linSol2.groupEs(['4.0x', '-', '2.0e', '-', '4'])
>>> print(x)
['4.0x', '-', '2.0e-4']

But when I run the test in Command Prompt, it fails. Instead it produces the following result:

======================================================================
FAIL: test_groupEs (__main__.linSol2tests)
----------------------------------------------------------------------
Traceback (most recent call last):
    File "linSol2_test.py", line 135, in test_groupEs
        self.assertEqual(linSol2.groupEs(in_list), out_list)
AssertionError: Lists differ: ['4.0x', '-', '2.0e-4'] != ['4.0x', '-2.0e4']

First differing element 1:
-
-2.0e4

First list contains 1 additional elements.
First extra element 2:
2.0e-4

- ['4.0x', '-', '2.0e-4']
?            ----

+ ['4.0x', '-2.0e-4']

Other tests in groupEs_tests such as

(['12e', '-', '7', '-', '4e', '+', '6'], ['12e-7', '-', '4e+6']),
(['e', '-', '2', '-', '7e', '+', '10'], ['e-2', '-', '7e+10'])

work when run from Command Prompt, so I've no idea why it's failing. Can anyone shed any light on the issue?

Note: using Python 3