Rustlings result1: Using custom enum variants as errors in Result return types

Chris Biscardi: [0:00] In result1, we have a new struct that contains a value of u64. We also derive PartialEq and Debug for both the struct and the Error enum that we use in our result type for the implementation of the new method inside of our struct.

[0:13] You can see that currently, our implementation always returns OK with the PositiveNonzeroInterger constructor, and the value. If we look at our test, we can see that we have a failure, specifically on the assert_eq! Where we pass in a negative number. We expect the value to come back as a CreationError but the value is Negative.

[0:31] In the implementation of new, we can check to see if this is a negative integer. Remember, we need to return a result type, so we'll wrap this in Err, and we'll specify that as a (CreationError::Negative). We can also check if the value is zero and do the same thing. In this case, we'll be using the Err (CreationError::Zero). Otherwise, we can return OK with the value.