# Lecture 7

1. ### Black Box and Glass Box Testing

With the below implementation, is the test set "n = 4 | n = -4 | n = 5" path complete?

````def is_even(n):`
`    """ `
`    Returns True if a number is even`
`    and False if not `
`    """`
`    if n > 0 and n % 2 == 0:`
`        return True`
`    elif n < 0 and n % 2 == 0:`
`        return True`
`    else: `
`        return False`
```
Exercise 1

2. With the above implementation, which value for n is incorrectly labeled by is_even?

Exercise 2

Flash and JavaScript are required for this feature.

3. ### Errors

Below is a piece of code and an error shown when running it. What is the problem?

````L = 3`
`for i in range(len(L)):`
`    print(i)`

`ERROR MESSAGE:`

` File "C:/Users/Ana/.spyder2-py3/temp.py", line 2, in `
`    for i in range(len(L)):`

`TypeError: object of type 'int' has no len()`

```
Exercise 3

Flash and JavaScript are required for this feature.

4. ### Exceptions

If the user enters "twenty" in the code below what does the program do?

````try:`
`    n = int(input("How old are you? "))`
`    percent = round(n*100/80, 1)`
`    print("You've gone through", percent, "% of your life!")`
`except ValueError:`
`    print("Oops, must enter a number.")`
`except ZeroDivisionError:`
`    print("Division by zero.")`
`except:`
`    print("Something went very wrong.")`
```
Exercise 4

5. If the user enters "0" in the code above what does the program do?

Exercise 5

Flash and JavaScript are required for this feature.