without_internet simulates the situation when any network request will
fail, as in when you are without an internet connection. Any HTTP request
through the verb functions in httr will raise an error.
without_internet(expr)The result of expr
The error message raised has a well-defined shape, made of three
elements, separated by space: (1) the request
method (e.g. "GET"); (2) the request URL; and
(3) the request body, if present. The verb-expectation functions,
such as expect_GET() and expect_POST(), look for this shape.
block_requests() to enable mocking on its own (not in a context)