handle cases when httr/crul writes to disk

[sckott]

investigate if same problem occurs with httr or not.

use case right now is rnoaa, where many functions write to disk - vcr is throwing erors like: with this block https://github.com/ropensci/rnoaa/blob/master/tests/testthat/test-buoy.R#L26-L41

test-buoy.R:33: error: buoy works
argument 'x' must be a raw vector
1: vcr::use_cassette("buoys_parameters", {
       one <- buoy(dataset = "cwind", buoyid = 41001, year = 1997, datatype = "c") at tests/testthat/test-buoy.R:33
2: cassette$call_block(...)
3: lazyeval::lazy_eval(tmp)
4: lapply(x, lazy_eval, data = data)
5: FUN(X[[i]], ...)
6: eval(x$expr, x$env, emptyenv())
7: eval(x$expr, x$env, emptyenv())
8: buoy(dataset = "cwind", buoyid = 41001, year = 1997, datatype = "c") at tests/testthat/test-buoy.R:34
9: get_ncdf_file(path = toget, buoyid, file = files[[1]], output, ...) at /Users/sckott/github/ropensci/rnoaa/R/buoy.R:89
10: crul::HttpClient$new(path, opts = list(...))$get(disk = outpath) at /Users/sckott/github/ropensci/rnoaa/R/buoy.R:146
11: private$make_request(rr)
12: adap$handle_request(opts)
13: vcr::RequestHandlerCrul$new(req)$handle()
14: eval(parse(text = req_type_fun))(self$request)
15: cas$record_http_interaction(response)
16: self$make_http_interaction(x)
17: VcrResponse$new(if (inherits(x, "response")) httr::http_status(x) else unclass(x$status_http()),
       if (inherits(x, "response")) x$headers else x$response_headers, rawToChar(x$content),
18: .subset2(public_bind_env, "initialize")(...)
19: inherits(body, "list")
20: rawToChar(x$content)

[sckott]

possible plan:

• check class inherits(x$content, "character"), and then
• check if the file exists file.exists(x$content)
• if file exists
  • create hashed file name (for now: fff) from ???
  • copy file to fff
  • make sure file path in cassette is fff
• if file doesn't exist
  • fail out (e.g., "you attempted to write to disk but the file does not exist")
• On reuse of a cassette with a file on disk, make sure to read the file on disk first, and place bytes in $content slot before returning to the calling function

location o f cached files (e.g., fff) should be in a folder at the root of the user given directory, so if they give the dir as fixtures, then we do

fixtures
└── file_cache
    └── fff

this is def. going to be slow, but overall speeds up test suite, so fine

should also tell users that they can alternatively just read into memory then write to disk after and vcr will work already as is

[sckott]

applies to both:

• crul
• httr

and

• curl if we integrate it here (and in webmockr)

[sckott]

• crul: needs to have the file path in content slot in HttpResponse object
• httr: same but path has to have s3 "path" class attached

[sckott]

related fix in crul ropensci/crul#115

[sckott]

here's a tough case: where the fxn caches a file from the HTTP request somewhere on disk - how do we deal with this in a vcr testing context?

an example is rnoaa::cpc_prcp - see experiments on branch vcr-write-disk