Renamed /tests/tests.R to /tests/main.R and added long note to NEWS a…

…bout why test_package(data.table) will now fail for users and what to do.

NEWS.md

@@ -329,6 +329,8 @@
   38. Logical `i` is no longer recycled. Instead an error message if it isn't either length 1 or `nrow(DT)`. This was hiding more bugs than was worth the rare convenience. The error message suggests to recycle explcitly; i.e. `DT[rep(<logical>,length=.N),...]`.
 
   39. Thanks to Mark Landry and Michael Chirico for finding and reporting a problem in dev before release with auto `with=FALSE` (item 3 above) when `j` starts with with `!` or `-`, [#1864](https://github.com/Rdatatable/data.table/issues/1864). Fixed and tests added.
+
+  40. Following latest recommended testthat practices and to avoid a warning that it now issues, `inst/tests/testthat` has been moved to `/tests/testthat`. This means that testthat tests won't be installed for use by users by default and that `test_package("data.table")` will now fail with error `No matching test file in dir` and also a warning `Placing tests in inst/tests/ is deprecated. Please use tests/testthat/ instead`. (That warning seems to be misleading since we already have made that move.) To install testthat tests (and this applies to all packages using testthat not just data.table) you need to follow the [deleted instructions](https://github.com/hadley/testthat/commit/0a7d27bb9ea545be7da1a10e511962928d888302) in testthat's README; i.e., reinstall data.table either with `--install-tests` passed to `R CMD INSTALL` or `INSTALL_opts = "--install-tests"` passed to `install.packages()`. After that, `test_package("data.table")` will work. However, the main test suite of data.table (5,000+ tests) doesn't use testthat at all. Those tests are always installed so that `test.data.table()` can always be run by users at any time to confirm your installation on your platform is working correctly. Sometimes when supporting you, you may be asked to run `test.data.table()` and provide the output. Particularly now that data.table uses OpenMP. The file `/tests/tests.R` (which just calls `test.data.table()`) has been renamed to `/tests/main.R` to make this clearer to those looking at the GitHub repository and a comment has been added to `/tests/main.R` pointing to `/inst/tests/tests.Rraw` where those tests live. Some of these tests test data.table's compability with other packages and that is the reason those packages are listed in `DESCRIPTION:Suggests`. If you don't have some of those packages installed, `test.data.table()` will print output that it has skipped tests of compatibility with those packages. On CRAN all Suggests packages are available and data.table's tests of compatibility with them are tested by CRAN every day.
 
 ### Changes in v1.9.6  (on CRAN 19 Sep 2015)
 

tests/tests.R → tests/main.R

@@ -1,7 +1,7 @@
 require(data.table)
-test.data.table()
+test.data.table()  # runs the main test suite of 5,000+ tests in /inst/tests/tests.Rraw
 
-# Turn off verbose repeat to save time (particularly Travis, but also CRAN)
+# Turn off verbose repeat to save time (particularly Travis, but also CRAN) :
 # test.data.table(verbose=TRUE)
 # Calling it again in the past revealed some memory bugs but also verbose mode checks the verbose messages run ok
 # TO DO: check we test each verbose message at least once, instead of a full repeat of all tests