tests/compose: Use workdir in tmpdir

This way when debugging if I want to preserve the state so I can
go there and rerun command under gdb for exmaple, all I need
to do is set `env TEST_SKIP_CLEANUP=1` rather than also needing
to find a separate dir and also set `env RPMOSTREE_PRESERVE_TMPDIR=1`.

Closes: #1630
Approved by: jlebon

tests/compose-tests/libcomposetest.sh

@@ -63,10 +63,14 @@ EOF
 }
 
 composejson=$(pwd)/compose.json
-compose_base_argv="--repo ${repobuild} --write-composejson-to ${composejson}"
+compose_workdir=${test_tmpdir}/workdir
+compose_base_argv="--workdir ${compose_workdir} --repo ${repobuild} --write-composejson-to ${composejson}"
 runcompose() {
     echo "$(date): starting compose"
-    rpm-ostree compose tree ${compose_base_argv} ${treefile} "$@"
+    # The workdir will be cleaned up (or not) with the overall test dir
+    rm ${compose_workdir} -rf
+    mkdir ${test_tmpdir}/workdir
+    env RPMOSTREE_PRESERVE_TMPDIR=1 rpm-ostree compose tree ${compose_base_argv} ${treefile} "$@"
     commit=$(jq -r '.["ostree-commit"]' < "${composejson}")
     ostree --repo=${repo} pull-local ${repobuild} "${treeref:-${commit}}"
     echo "$(date): finished compose"

tests/compose-tests/test-machineid-compat.sh

@@ -12,6 +12,8 @@ pysetjsonmember "units" '["tuned.service"]'
 
 # Do the compose -- we call compose directly because `set -e` has no effect when
 # calling functions within an if condition context
+rm ${compose_workdir} -rf
+mkdir ${test_tmpdir}/workdir
 if rpm-ostree compose tree ${compose_base_argv} ${treefile} |& tee err.txt; then
     assert_not_reached err.txt "Successfully composed with units and machineid-compat=False?"
 fi