libjob: duration is not optional in jobspecV1

Problem: Per RFC25, attributes.system.duration is not optional
in jobspecV1.  However, libjob considers it optional in its parsing.

Solution: Update parsing to make attributes.system.duration a
requirement.  Also check for jobspec version 1 before parsing
job duration.

Update expected output in t/t0022-jj-reader.t and t/t2300-sched-simple.t
as expected error message will now be different.

Author: chu11

src/common/libjob/jj.c

@@ -124,18 +124,20 @@ int jj_get_counts_json (json_t *jobspec, struct jj_counts *jj)
         errno = EINVAL;
         return -1;
     }
-    if (json_unpack_ex (jobspec, &error, 0, "{s:{s?{s?F}}}",
-                        "attributes",
-                          "system",
-                            "duration", &jj->duration) < 0) {
+    if (version != 1) {
         snprintf (jj->error, sizeof (jj->error) - 1,
-                  "at top level: getting duration: %s", error.text);
+                 "Invalid version: expected 1, got %d", version);
         errno = EINVAL;
         return -1;
     }
-    if (version != 1) {
+    /* N.B. attributes.system is generally optional, but
+     * attributes.system.duration is required in jobspec version 1 */
+    if (json_unpack_ex (jobspec, &error, 0, "{s:{s:{s:F}}}",
+                        "attributes",
+                          "system",
+                            "duration", &jj->duration) < 0) {
         snprintf (jj->error, sizeof (jj->error) - 1,
-                 "Invalid version: expected 1, got %d", version);
+                  "at top level: getting duration: %s", error.text);
         errno = EINVAL;
         return -1;
     }

t/t0022-jj-reader.t

@@ -66,7 +66,7 @@ test_expect_success 'jj-reader: wrong count type throws error' '
 # jobspec.yaml ==<expected error>
 #
 cat <<EOF>invalid.txt
-jobspec/valid/basic.yaml        ==jj-reader: Unable to determine slot size
+jobspec/valid/basic.yaml        ==jj-reader: at top level: getting duration: Object item not found: system
 jobspec/valid/example2.yaml     ==jj-reader: Unable to determine slot size
 jobspec/valid/use_case_1.2.yaml ==jj-reader: level 0: Expected integer, got object
 jobspec/valid/use_case_1.3.yaml ==jj-reader: level 2: Expected integer, got object

t/t2300-sched-simple.t

@@ -78,7 +78,7 @@ test_expect_success 'sched-simple: invalid minimal jobspec is canceled' '
 	${Y2J}<${SPEC} | jq ".version = 1" | flux job submit >job00.id &&
 	jobid=$(cat job00.id) &&
 	flux job wait-event --timeout=5.0 $jobid exception &&
-	flux job eventlog $jobid | grep "Unable to determine slot size"
+	flux job eventlog $jobid | grep "getting duration: Object item not found: system"
 '
 test_expect_success 'sched-simple: submit 5 jobs' '
 	flux job submit basic.json >job1.id &&