10-Dev: `make check` in mgmt2 removes files installed by `make install`

[bneradt]

The 10-Dev coverage builds are failing in opensource CI. Here's a current example:
https://ci.trafficserver.apache.org/view/10-Dev/job/10-Dev/job/coverage/13/console

The reason it fails is because the run of the regression tests fails because the installed traffic_server binary no longer exists at the time it tries to run them:

+ /tmp/ats/bin/traffic_server -K -k -R 1
/home/jenkins/workspace/10-Dev/coverage/src@tmp/durable-5ab76cb8/script.sh: line 4: /tmp/ats/bin/traffic_server: No such file or directory

The --prefix configure the CI uses is /tmp/ats. Experimenting with things locally, I notice that the previous make install call does indeed populate /tmp/ats/bin/traffic_server along with the other installed files, but the latter make check call deletes the files from that directory. Further, I notice that the make check call in mgmt2 removes those files.

Here's a session demonstrating this:

$ git show --no-patch --oneline
1e6620bf2 (HEAD -> fix_10dev_coverage, upstream/10-Dev) Fixes the cache unit tests by removing an undeclared class function, (#8782)

$ make install > /dev/null 2>&1
$ ls /tmp/ats
bin  etc  include  lib  libexec  share  var

$ make check > /dev/null 2>&1

$ ls /tmp/ats
lib

Notice that after make check, only lib remains in the install directory.

This problem does not happen on master. Only for 10-Dev.

[bneradt]

With some further experimentation, it looks like the mgmt2's test_jsonrpcserver test removes the installed files:

$ make install > /dev/null 2>&1
$ ls /tmp/ats
bin  etc  include  lib  libexec  share  var

$ ./mgmt2/rpc/.libs/test_jsonrpcserver > /dev/null 2>&1

$ ls /tmp/ats
lib

[bneradt]

I see. The problem is setting sandboxDir to fs::temp_directory_path here which will be /tmp/

trafficserver/mgmt2/rpc/server/unit_tests/test_rpcserver.cc

Line 506 in 1e6620b

fs::path sandboxDir = fs::temp_directory_path();

Then removing it here:

trafficserver/mgmt2/rpc/server/unit_tests/test_rpcserver.cc

Line 536 in 1e6620b

REQUIRE(fs::remove(sandboxDir, ec));

Rather it should use getTemporaryDir() (or something like it) which returns a temporary directory (i.e., not /tmp/ but something from mkdtemp) like here:

trafficserver/proxy/http/remap/unit-tests/test_PluginFactory.cc

Line 105 in 1e6620b

static fs::path sandboxDir = getTemporaryDir();