R - mocking API requests with `gh` package - r

Question

I am trying to mock the output of a gh API request:
httptest2::with_mock_dir("gh", {
test_that("api works", {
gh::gh("GET /repos/r-lib/gh")
})
})
I am trying to set up testing for custom functions that routinely make API calls to GitHub and I am using gh to make these requests. I am following this tutorial as guidance: https://books.ropensci.org/http-testing/
However, no directory is created when this function is run. Is there anyway to capture the output of gh::gh and store it as a mock API return so that I can run my tests without needing GitHub authentication or even an internet connection?

Answer 1

httptest2 is specifically designed to test httr2 requests:
This package helps with writing tests for packages that use httr2
Unfortunately, gh uses httr:
Imports:
cli (>= 3.0.1),
gitcreds,
httr (>= 1.2),
ini,
jsonlite
This means that you can't directly use httptest2 with gh.
However, using gh source code, you can extract the parameters of the GET request sent to httr by gh:
gh_get <- function(endpoint, ..., per_page = NULL, .token = NULL, .destfile = NULL,
.overwrite = FALSE, .api_url = NULL, .method = "GET",
.limit = NULL, .accept = "application/vnd.github.v3+json",
.send_headers = NULL, .progress = TRUE, .params = list()) {
params <- c(list(...), .params)
params <- gh:::drop_named_nulls(params)
if (is.null(per_page)) {
if (!is.null(.limit)) {
per_page <- max(min(.limit, 100), 1)
}
}
if (!is.null(per_page)) {
params <- c(params, list(per_page = per_page))
}
req <- gh:::gh_build_request(
endpoint = endpoint, params = params,
token = .token, destfile = .destfile,
overwrite = .overwrite, accept = .accept,
send_headers = .send_headers,
api_url = .api_url, method = .method
)
req
}
req <- gh_get("GET /repos/r-lib/gh")
req
#$method
#[1] "GET"
#$url
#[1] "https://api.github.com/repos/r-lib/gh"
#$headers
# User-Agent Accept
# "https://github.com/r-lib/gh" "application/vnd.github.v3+json"
#$query
#NULL
#$body
#NULL
#$dest
#<request>
#Output: write_memory
This allows with the example you provided to use httr2 to send the same request :
library(httr2)
resp_httr2 <- request(base_url=req$url) %>%
req_perform() %>%
resp_body_json()
If you are mainly interested in json content, the results are the same, only the attributes differ :
resp_gh <- gh::gh("GET /repos/r-lib/gh")
all.equal(resp_gh,resp_httr2,check.attributes=FALSE)
#[1] TRUE
If you want to use httptest2, switching to httr2 would work:
with_mock_dir("gh", {
test_that("api works", {
resp <- request(base_url=req$url) %>%
req_perform() %>%
resp_body_json()
expect_equal(resp$full_name,"r-lib/gh")})
})
#Test passed 🎉
#[1] TRUE
Offline testing now works because gh\api.github.com directory was created by httptest2.

Answer 2

Maybe you can take inspiration from tests/testthat/test-mock-repos.R
res <- gh(
TMPL("/repos/{owner}/{repo}"),
owner = "gh-testing",
repo = test_repo,
.token = tt()
)
expect_equal(res$name, test_repo)
expect_equal(res$description, "Test repo for gh")
expect_equal(res$homepage, "https://github.com/r-lib/gh")
expect_false(res$private)
expect_false(res$has_issues)
expect_false(res$has_wiki)
A GET method would not create any directory.