Add token instructions + support for GITHUB_PAT and GITHUB_TOKEN

[isteves]

In this PR, I made the following changes:

• added get_tokens() to retrieve tokens in the following order of precedence: 1. GITHUB_GRAPHQL_TOKEN 2. GITHUB_TOKEN 3. GITHUB_PAT
• changed iterate() to stop and return error message given in responses
• added a note about tokens in the README

It's probably a good idea to add a test, but I'm not sure what the best way is of doing that.

Relevant issues/code that came up in my discussion with @maelle :
#6
ropensci/ghql#11
https://github.com/r-lib/whoami/blob/master/R/whoami.R#L279
https://github.com/r-lib/gh/blob/bed43d354789d2e4dde75db0327da1d46358f953/R/gh_request.R#L143

[maelle]

This looks great! And such a great PR description! 👏

To add testing, we'd need to rely on mocking. I wasn't able to find a resource for a how to mock a function depending on its arguments (https://github.com/r-lib/whoami/blob/master/tests/testthat/test-gh-username.R#L25 felt hacky even if it works and was merged 😂).

I wonder whether it'd be overkill to define 3 helpers:

get_github_token <- function(...){
  Sys.getenv("GITHUB_TOKEN", ...)
}
get_github_path <- function(){
  Sys.getenv("GITHUB_PAT")
}

and mock their behavior to see what get_token does. Or at least to test part of the behavior. What do you think?

[maelle]

Two other notes

• If you don't have time I could work on the tests myself.

• In any case, please add yourself as "ctb" by installing whoami and then running desc::desc_add_me()! With the dev desc version if you save your ORCID_ID as environment variable, it'll get added as well.

[isteves]

What do you think of this test for get_token? I based it off your whoami example + added a function factory (my first on ever!)

context("test-get_token")

test_that("check that correct token is retrieved", {
  mock_sysgetenv <- function(gh_graphql, gh_token, gh_pat) {
    function(x, unset = ""){
      token <- switch(x,
                      "GITHUB_GRAPHQL_TOKEN" = gh_graphql,
                      "GITHUB_TOKEN" = gh_token,
                      "GITHUB_PAT" = gh_pat)
      if(token != "") return(token)
      return(unset)
    }
  }

  with_mock(
    Sys.getenv = mock_sysgetenv("aa", "bb", "cc"),
    expect_equal(get_token(), "aa")
  )

  with_mock(
    Sys.getenv = mock_sysgetenv("", "bb", "cc"),
    expect_equal(get_token(), "bb")
  )

  with_mock(
    Sys.getenv = mock_sysgetenv("", "", "cc"),
    expect_equal(get_token(), "cc")
  )

  with_mock(
    Sys.getenv = mock_sysgetenv("", "", ""),
    expect_error(get_token())
  )
})

[maelle]

wow I might only have written one function factory! It looks great!

[isteves]

Ok, I added the test and added myself as a contributor. Couldn't figure out how to use desc so just did it manually 😬

[maelle]

Thank you! Will review next week.

[maelle]

Oops I snoozed the reminder too much! On it now!

[maelle]

Thanks again!

[isteves]

Woot!