Phone Number

Write a program that cleans up user-entered phone numbers so that they can be sent SMS messages.

The rules are as follows:

If the phone number is less than 10 digits assume that it is bad number
If the phone number is 10 digits assume that it is good
If the phone number is 11 digits and the first number is 1, trim the 1 and use the last 10 digits
If the phone number is 11 digits and the first number is not 1, then it is a bad number
If the phone number is more than 11 digits assume that it is a bad number

We've provided tests, now make them pass.

Hint: Only make one test pass at a time. Disable the others, then flip each on in turn after you get the current failing one to pass.

To run the tests simply run the command go test in the exercise directory.

If the test suite contains benchmarks, you can run these with the -bench flag:

go test -bench .

For more detailed info about the Go track see the help page.

Source

It's possible to submit an incomplete solution so you can see how others have completed the exercise.