Use tutorial, round 2

[angela-li]

Closes #314 use_tutorial()

Making this PR properly from a branch instead of master of my forked repo, incorporating code review edits in #584

Merge me instead of #584! 😄

[angela-li]

Looks like builds are failing because learnr isn't installed in Appveyor/Travis?

[jennybc]

Thanks! I made a few comments.

[jennybc]

There's a test failing on AppVeyor and Travis. You probably need to use the same mocking strategy we use elsewhere to get around the need for learnr to be installed.

usethis/tests/testthat/test-use-roxygen.R

Lines 18 to 29 in b0df5f1

	with_mock(
	## need to pass the check re: whether roxygen2md is installed
	`usethis:::check_installed` = function(pkg) TRUE, {
	scoped_temporary_package()
	cat(
	"RoxygenNote: 6.0.1\n",
	file = proj_path("DESCRIPTION"),
	append = TRUE
	)
	expect_error_free(use_roxygen_md())
	}
	)

[jennybc]

@garrettgman If you took this for a spin, that would be great. It basically looks good to me, so I plan to merge soon, after we wrap up the loose ends.

[jennybc]

Can you also please add a bullet to NEWS? It should briefly describe the change and end with (@yourname, #issuenumber).

[jennybc]

Good grief it took me a while to get the test and mocking sorted -- probably just as well that I was the one to suffer through that.

Thanks!

[angela-li]

You caught me at a busy time, but thanks for helping out with the rest of the edits! Appreciate your support on this (thanks for figuring out the mocking). It's exciting to see use_tutorial added into usethis 👏