In Python3, how can I fix this unittest.TestCase class, SetUp(self) method and call to unittest.main()?

I've been completing challenge exercises from an introductory python textbook (python3), and for one of these I've made a python program that imports a class called Employee from another python file. They are both working properly. I've also made a program to run tests on the class. This test program produces the following errors:

EE
======================================================================
ERROR: test_give_custom_raise (__main__.TestEmployee)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "........python_projects/py_crash_course/py_crash_chap11/test_employee.py", line 19, in test_give_custom_raise
    test_custom = self.employee_instance.give_raise(self.custom_raise)
AttributeError: 'TestEmployee' object has no attribute 'employee_instance'

======================================================================
ERROR: test_give_default_raise (__main__.TestEmployee)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "....python_projects/py_crash_course/py_crash_chap11/test_employee.py", line 14, in test_give_default_raise
    employee_instance.give_raise(test_salary='1')
NameError: name 'employee_instance' is not defined

----------------------------------------------------------------------
Ran 2 tests in 0.000s

FAILED (errors=2)
[Finished in 0.1s with exit code 1]

The code in the test program is as follows:

"""Tests the class: Employee contained in the file: employee_class.py"""

import unittest
from employee_class import Employee

class TestEmployee(unittest.TestCase):
    """Tests if the class: Employee works for both the default raise and a custom raise."""
    """Creates .... for use in all test methods."""
    def SetUp(self):
        self.custom_raise = 1000000
        self.employee_instance = Employee()
        self.employee_instance.give_raise(test_salary='1')
        
    def test_give_default_raise(self):
        self.assertEqual(TestEmployee.give_raise.salary, 5001)

    def test_give_custom_raise(self):
        test_custom = self.employee_instance.give_raise(self.custom_raise)
        self.assertEqual(self.test_custom, self.custom_raise)

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

The code in the program containing the class is as follows:

import json

class Employee:
    """"""
    def __init__(self, pay_raise=5000):
        self.pay_raise = pay_raise
        self.employee_details_list = []
        self.saved_details = "saved_employee_details.json"
        with open(self.saved_details) as s:
            self.employee_details_dictionary = json.load(s)
        
    def get_details(self):
        self.first_name = input("Enter employee's first name: ").lower()
        self.last_name = input("Enter employee's last name: ").lower()
        not_yet = True
        while not_yet:
            try:
                self.salary = int(input("Enter employee's salary (do not include the dollar sign or commas or spaces): "))
                not_yet = False
            except ValueError:
                print("You cannot enter a dollar sign($), spaces, commas(,) or decimal point(.).")
                print("You can only enter numerical digits.")


    def make_list(self):
        self.employee_details_list.append(self.first_name)
        self.employee_details_list.append(self.salary)

    def determine_pay_raise(self):
        not_answered = True
        y_n = ["y", "n"]
        while not_answered:
            custom_pay_raise_y_n = input("Will the employee get a custom pay raise? (y/n): ")
            if custom_pay_raise_y_n not in y_n:
                print("You can only enter 'y' for 'yes, or 'n' for 'no'.")
            if custom_pay_raise_y_n == "n":
                break
            if custom_pay_raise_y_n == "y":
                not_yet = True
                while not_yet:
                    try:
                        self.pay_raise = int(input("Enter the amount of the pay raise (do not include the dollar sign,\n commas, spaces or decimal point): "))
                        not_answered = False
                        not_yet = False
                    except ValueError: 
                        print("You cannot enter a dollar sign($), spaces, commas(,) or decimal point(.).")


    def give_raise(self, test_value='', test_salary=''):
        self.test_value = test_value
        if self.test_value == '':
            self.salary += self.pay_raise
            return self.salary
            self.employee_details_list[-1] = self.salary
        if self.test_value !='':
            self.salary += self.test_value
            self.employee_details_list[-1] = self.salary
            return self.salary

            
    def add_to_dictionary(self):
        self.employee_details_dictionary[self.last_name] = self.employee_details_list

    def save_details(self):
        with open(self.saved_details, "w") as s:
            contents = self.employee_details_dictionary
            json.dump(contents, s)

    def print_new_salary(self):
        print(f"{self.first_name.title()} {self.last_name.title()}'s new annual salary is ${self.salary}")

And the code in the main program is as follows:

from employee_class import Employee 

keep_going = True
while keep_going:

   IndividualEmployee = Employee()

   IndividualEmployee.get_details()

   IndividualEmployee.make_list()

   IndividualEmployee.determine_pay_raise()

   IndividualEmployee.give_raise()

   IndividualEmployee.add_to_dictionary()

   IndividualEmployee.save_details()

   IndividualEmployee.print_new_salary()

   y_n = ["y", "n"]
   not_yet = True
   while not_yet:
       another_employee = input("\nDo you want to input information for another employee? (y/n): ")
       if another_employee not in y_n:
           print("You can only enter 'y' for 'yes', or 'n' for 'no'.\n")
       if another_employee == "n":
           keep_going = False
           break
       if another_employee == "y":
           not_yet = False
print("\n")

I don't understand why the test program is producing these errors. In particular, in the test program, I feel like I have defined the variable 'employee_instance' in the SetUp() function in the test program. Why isn't it being recognised? How can I fix it?

Thanks!