Suggestions when testing a program which has string input(s)
When testing a program with string input, you should consider in general
Of course depending on the exact problem, the contents of the string may have to be varied. For example, the string may have to contain commas or it may end with a newline character, etc.
If you are using the turtle graphics library function textinput, you should consider what happens if the user hits the "Cancel" button.
Testing for "Non-numeric input" on a string input is usually not important. If you're inputting a string of characters, any characters are accepted if you are not planning to convert to numbers later.