fails:ENV.store sets the environment variable to the given value
fails:ENV.store returns the value
fails:ENV.store deletes the environment variable when the value is nil
fails:ENV.store coerces the key argument with #to_str
fails:ENV.store coerces the value argument with #to_str
fails:ENV.store raises TypeError when the key is not coercible to String
fails:ENV.store raises TypeError when the value is not coercible to String
fails:ENV.store raises Errno::EINVAL when the key contains the '=' character
fails:ENV.store raises Errno::EINVAL when the key is an empty string
fails:ENV.store does nothing when the key is not a valid environment variable key and the value is nil
