safename: consistent within same test, and, dashes

Make safename() invocations consistent within the same
test. This puts the onus on the caller to add a unique
element when calling multiple times, e.g. "ctr1-$(safename)".
This is not too much of a burden. Major benefit is making
it easy for a reader to associate containers, pods, volumes,
images within a given test.

And, use dashes, not underscores. "podman generate kube"
removes underscores, making it very difficult to do
things like "podman inspect $podname" (because we need
to generate "$podname_with_underscores_removed")

Signed-off-by: Ed Santiago <santiago@redhat.com>

test/system/helpers.bash

@@ -1157,14 +1157,22 @@ function random_string() {
 #  safename  #  Returns a pseudorandom string suitable for container/image/etc names
 ##############
 #
-# Name will include the bats test number, eg "t123_xyz123". When/if we
-# ever parallelize system tests, this will make it possible to check
-# for leaks and identify the test that leaked.
+# Name will include the bats test number and a pseudorandom element,
+# eg "t123-xyz123". safename() will return the same string across
+# multiple invocations within a given test; this makes it easier for
+# a maintainer to see common name patterns.
 #
 # String is lower-case so it can be used as an image name
 #
 function safename() {
-    echo "t${BATS_SUITE_TEST_NUMBER}_$(random_string 8 | tr A-Z a-z)"
+    # FIXME: I don't think these can ever fail. Remove checks once I'm sure.
+    test -n "$BATS_SUITE_TMPDIR"
+    test -n "$BATS_SUITE_TEST_NUMBER"
+    safenamepath=$BATS_SUITE_TMPDIR/.safename.$BATS_SUITE_TEST_NUMBER
+    if [[ ! -e $safenamepath ]]; then
+        echo -n "t${BATS_SUITE_TEST_NUMBER}-$(random_string 8 | tr A-Z a-z)" >$safenamepath
+    fi
+    cat $safenamepath
 }
 
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