capture_requests() is a context that collects the responses from requests
you make and stores them as mock files. This enables you to perform a series
of requests against a live server once and then build your test suite using
those mocks, running your tests in with_mock_api().
capture_requests(expr, simplify = TRUE)
start_capturing(simplify = TRUE)
stop_capturing()Code to run inside the context
logical: if TRUE (default), plain-text responses with status 200
will be written as just the text of the response body. In all other cases,
and when simplify is FALSE, the httr2_response object will be written out to
a .R file using base::dput().
capture_requests() returns the result of expr. start_capturing()
invisibly returns the destination directory.
stop_capturing() returns nothing; it is called for its side effects.
start_capturing() and stop_capturing() allow you to turn on/off request
recording for more convenient use in an interactive session.
Recorded responses are written out as plain-text files. By storing fixtures as plain-text files, you can more easily confirm that your mocks look correct, and you can more easily maintain them without having to re-record them. If the API changes subtly, such as when adding an additional attribute to an object, you can just touch up the mocks.
If the response has status 200 OK and the Content-Type
maps to a supported file extension---currently .json,
.html, .xml, .txt, .csv, and .tsv---just the response body will be
written out, using the appropriate extension. 204 No Content status
responses will be stored as an empty file with extension .204. Otherwise,
the response will be written as a .R file containing syntax that, when
executed, recreates the httr2_response object.
Files are saved to the first directory in .mockPaths(), which if not
otherwise specified is either "tests/testthat" if it exists
(as it should if you are in the root directory of your package),
else the current working directory.
If you have trouble when recording responses, or are unsure where the files
are being written, set options(httptest2.verbose = TRUE) to print a message
for every file that is written containing the absolute path of the file.
build_mock_url() for how requests are translated to file paths.
And see vignette("redacting", package = "httptest2")
for details on how to prune sensitive content from responses when recording.
if (FALSE) {
# Setup so that our examples clean up after themselves
tmp <- tempfile()
.mockPaths(tmp)
on.exit(unlink(tmp, recursive = TRUE))
library(httr2)
capture_requests({
request("http://httpbin.org/get") %>% req_perform()
request("http://httpbin.org/response-headers") %>%
req_headers(`Content-Type` = "application/json") %>%
req_perform()
})
# Or:
start_capturing()
request("http://httpbin.org/get") %>% req_perform()
request("http://httpbin.org/response-headers") %>%
req_headers(`Content-Type` = "application/json") %>%
req_perform()
stop_capturing()
}