Know how function with external methods was called without editing it in Python

I couldn’t find an answer so I ask:

Let’s say I have a file with these functions:

def method_1(param1, param2):
    send_email(param1)
    print('method_1 is done')               
    
def method_2(param1, param2):
    new_param = external_method(param1)
    method_1(new_param['key'], param2)
    print('method_2 is done')

They are part of some MVC framework, and I’m trying to write a test, so changing the functions is not an option. The test would be to check whether the sent email is correct.

external_method() depends on an external API, so I don’t know what it will return, meaning that whatever I write to mock it, it will be inaccurate to a real-life setting.

All I know about external_method‘s result is that it should be in the form of a dict and contain a key called 'key'

Without editing the code above, is there a way to know if send_email inside method_1 was called with the right param1? Meaning that the email contains what I expect it to contain based on the origin of param1.

I know that I could use a runtime debugger but I was wondering if there are other solutions.