Mocking writing to disk
Scott Chamberlain
2024-11-24
Source:vignettes/write-to-disk.Rmd
write-to-disk.Rmd
Request matching
If you have http requests for which you write the response to disk,
then use vcr_configure()
to set the
write_disk_path
option. See more about the write_disk_path
configuration option in
vignette("configuration", package = "vcr")
.
Here, we create a temporary directory, then set the fixtures
tmpdir <- tempdir()
vcr_configure(
dir = file.path(tmpdir, "fixtures"),
write_disk_path = file.path(tmpdir, "files")
)
#> <vcr configuration>
#> Cassette Dir: /tmp/RtmppSk4rz/fixtures
#> Record: once
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: method, uri
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path: /tmp/RtmppSk4rz/files
Then pass a file path (that doesn’t exist yet) to crul’s
disk
parameter. vcr
will take care of handling
writing the response to that file in addition to the cassette.
library(crul)
## make a temp file
f <- tempfile(fileext = ".json")
## make a request
cas <- use_cassette("test_write_to_disk", {
out <- HttpClient$new("https://httpbin.org/get")$get(disk = f)
})
file.exists(out$content)
#> [1] TRUE
out$parse()
#> [1] "{\n \"args\": {}, \n \"headers\": {\n \"Accept\": \"application/json, text/xml, application/xml, */*\", \n \"Accept-Encoding\": \"gzip, deflate\", \n \"Host\": \"httpbin.org\", \n \"User-Agent\": \"libcurl/8.5.0 r-curl/6.0.1 crul/1.5.0.91\", \n \"X-Amzn-Trace-Id\": \"Root=1-6742b8f0-64a1468179dd8b0725fe29ab\"\n }, \n \"origin\": \"68.154.24.198\", \n \"url\": \"https://httpbin.org/get\"\n}\n"
This also works with httr
. The only difference is that
you write to disk with a function httr::write_disk(path)
rather than a parameter.
Note that when you write to disk when using vcr
, the
cassette is slightly changed. Instead of holding the http response body
itself, the cassette has the file path with the response body.
http_interactions:
- request:
method: get
uri: https://httpbin.org/get
response:
headers:
status: HTTP/1.1 200 OK
access-control-allow-credentials: 'true'
body:
encoding: UTF-8
file: yes
string: /private/var/folders/fc/n7g_vrvn0sx_st0p8lxb3ts40000gn/T/Rtmp5W4olr/files/file177e2e5d97ec.json
And the file has the response body that otherwise would have been in
the string
yaml field above:
{
"args": {},
"headers": {
"Accept": "application/json, text/xml, application/xml, */*",
"Accept-Encoding": "gzip, deflate",
"Host": "httpbin.org",
"User-Agent": "libcurl/7.54.0 r-curl/4.3 crul/0.9.0"
},
"origin": "24.21.229.59, 24.21.229.59",
"url": "https://httpbin.org/get"
}
More documentation
Check out the http
testing book for a lot more documentation on vcr
,
webmockr
, and crul