possible webmockr integration

[sckott]

@jeroen opening this to start a discussion to see if you'd be willing to incorporate changes for webmockr - if so, if you have any thoughts on the changes I've made.

A few people have requested curl integration for webmockr, suggesting there's more than that that would use it.

I want an even smaller change (few lines of code) to curl than I've made in this PR - perhaps you can advise on how.

The only thing changed right now in my fork of curl is curl_fetch_memory(): I first check if webmockr is installed, if not move on. If installed, then check if webmocking for curl is enabled; if so then proceed to call webmockr::curl_mock_req: https://github.com/ropensci/webmockr/blob/adapter-curl/R/curl_mocking.R

example:

remotes::install_github("sckott/curl@mocking-minimal-footprint")
remotes::install_github("ropensci/webmockr@adapter-curl")

library(curl)
library(webmockr)

# before mocking turned on
h <- new_handle()
curl_fetch_memory("https://httpbin.org/get?foo=bar", h)
#> normal curl response

# after mocking turned on
enable("curl")
# fails with webmockr message
curl_fetch_memory("https://httpbin.org/get?foo=bar", h) 
#> Error: Real HTTP connections are disabled.
#> Unregistered request:
#>   GET:  https://httpbin.org/get?foo=bar   with headers {accept: */*, accept-encoding: gzip, deflate, host: localhost:9359, user-agent: R (3.5.2 x86_64-apple-darwin15.6.0 x86_64 darwin15.6.0)}
#> 
#> You can stub this request with the following snippet:
#> 
#>    stub_request('get', uri = 'https://httpbin.org/get?foo=bar') %>%
#>      wi_th(
#>        headers = list('accept' = '*/*', 'accept-encoding' = 'gzip, deflate', 'host' = 'localhost:9359', 'user-agent' = 'R (3.5.2 x86_64-apple-darwin15.6.0 x86_64 darwin15.6.0)')
#>      )
#> ============================================================

# after stubbing request
stub_request("get", "https://httpbin.org/get?foo=bar")
#> <webmockr stub>
#>   method: get
#>   uri: https://httpbin.org/get?foo=bar
#>   with:
#>     query:
#>     body:
#>     request_headers:
#>   to_return:
#>     status:
#>     body:
#>     response_headers:
#>   should_timeout: FALSE
#>   should_raise: FALS

# now you get a mocked response
curl_fetch_memory("https://httpbin.org/get?foo=bar", h)
#>  $url
#>  [1] "https://httpbin.org/get?foo=bar"
#>  
#>  $status_code
#>  [1] 200
#>  
#>  $type
#>  [1] NA
#>  
#>  $headers
#>  raw(0)
#>  
#>  $modified
#>  [1] NA
#>  
#>  $times
#>  numeric(0)
#>  
#>  $content
#>  raw(0)

---

other things:

• for curl_fetch_disk I need to work out handling disk operations in a general purpose way for any pacakge adapater (mock writing to disk  ropensci/webmockr#57), then can work on mocking for curl_fetch_disk

[jeroen]

Note from call: consider conditioning the callback on a unique secret header.

[codecov-io]

Codecov Report

Merging #174 into master will decrease coverage by 0.03%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##           master     #174      +/-   ##
==========================================
- Coverage   78.81%   78.77%   -0.04%     
==========================================
  Files          35       35              
  Lines        1369     1376       +7     
==========================================
+ Hits         1079     1084       +5     
- Misses        290      292       +2

Impacted Files	Coverage Δ
R/fetch.R	40.62% <71.42%> (+8.62%)	⬆️

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[jeroen]

I'm curious, how does webmockr::curl_mock_req know what is inside the handle? How does it know what the mocked request is?

[jeroen]

If curl would provide a way to explicitly let the handle be mock-able e.g. handle_allow_mock(h) or by setting a given request header, would that work, or is that impractical for how mocking is used?

[sckott]

how does webmockr::curl_mock_req know what is inside the handle?

by running curl::curl_echo https://github.com/ropensci/webmockr/blob/adapter-curl/R/curl_mocking.R#L25

How does it know what the mocked request is?

this https://github.com/ropensci/webmockr/blob/adapter-curl/R/curl_mocking.R#L37-L38 will pick up the stub for the matched request signature from webmockr

[sckott]

If curl would provide a way to explicitly let the handle be mock-able ...

would make things easier for sure as wouldn't have to run curl_echo

[sckott]

closing for now - we talked and decided to not do this