Fix TMPDIR in test_genrule_default_env

TMPDIR is not just an arbitrary environment variable that we expect to be passed
to tests; it is the place where we temporary files may be stored. This semantic
rule also applies to bazel itself. So TMPDIR has to point to a directory where
we can write to. Unfortunately, the only way we have to find out a directory to
write to is TMPDIR itself. So, create a fresh directory there and pass that
directory on as new value for TMPDIR to see if it is passed through to the
action.

Also, fix up the resetting of TMPDIR: do not assume unset is the same
as set to the empty string.

--
Change-Id: I378ae9196c33d988686e8a2a6d3c142238fe8aab
Reviewed-on: https://bazel-review.googlesource.com/#/c/4030
MOS_MIGRATED_REVID=127196634

1 files changed, 14 insertions, 5 deletions

diff --git a/src/test/shell/bazel/bazel_rules_test.sh b/src/test/shell/bazel/bazel_rules_test.sh
index 6b7c04ed1d..cd510872fe 100755
--- a/src/test/shell/bazel/bazel_rules_test.sh
+++ b/src/test/shell/bazel/bazel_rules_test.sh
@@ -229,18 +229,27 @@ genrule(
   cmd = "(echo \"PATH=$$PATH\"; echo \"TMPDIR=$$TMPDIR\") > $@",
 )
 EOF
-  local old_path="${PATH-}"
+  local old_path="${PATH}"
   local old_tmpdir="${TMPDIR-}"
+  local effective_tmpdir="${TMPDIR:-/tmp}"
+  local new_tmpdir=$(mktemp -d "${effective_tmpdir}/newfancytmpdirXXXXXX")
+  [ -d "${new_tmpdir}" ] || \
+    fail "Could not create new temporary directory ${new_tmpdir}"
   export PATH="/bin:/usr/bin:/random/path"
-  export TMPDIR="/some/path"
+  export TMPDIR="${new_tmpdir}"
   # batch mode to force reload of the environment
   bazel --batch build //pkg:test || fail "Failed to build //pkg:test"
-  export PATH="$old_path"
-  export TMPDIR="$old_tmpdir"
   assert_contains "PATH=/bin:/usr/bin:/random/path" \
     bazel-genfiles/pkg/test.out
-  assert_contains "TMPDIR=/some/path" \
+  assert_contains "TMPDIR=.*newfancytmpdir" \
     bazel-genfiles/pkg/test.out
+  if [ -n "${old_tmpdir}" ]
+  then
+    export TMPDIR="${old_tmpdir}"
+  else
+    unset TMPDIR
+  fi
+  export PATH="${old_path}"
 }
 
 function test_genrule_remote() {