Base JobBatch#complete? on the presence of completed_at.

The old logic was designed to figure out when to mark the
job batch as complete by setting the timestamp -- but
that has been moved into the lua script. Basing `complete?`
on the job jid sets is potentially risky since we have
discussed making some of the job batch redis keys expire
sooner than others. If the job jid set keys vanished from
redis the old logic would wrongly report the job batch
was not complete even though it was. The new logic
relies only on the `meta` key which is the primary key
used by a job batch to track its state.

lib/plines/job_batch.rb

@@ -132,7 +132,7 @@ def complete_job(qless_job)
     end
 
     def complete?
-      _complete?(pending_job_jids.length, completed_job_jids.length)
+      !!completed_at
     end
 
     def resolve_external_dependency(dep_name)
@@ -319,10 +319,6 @@ def update_external_dependency(dep_name, meth, jids)
       end
     end
 
-    def _complete?(pending_size, complete_size)
-      pending_size == 0 && complete_size > 0
-    end
-
     def time_from(meta_entry)
       date_string = meta[meta_entry]
       Time.iso8601(date_string) if date_string

spec/unit/plines/job_batch_spec.rb

@@ -501,23 +501,16 @@ def create_batch_with_job
     end
 
     describe "#complete?" do
-      it 'returns false when there are no pending or completed jobs' do
+      it 'returns true if the job batch has a completed_at timestamp' do
         batch = JobBatch.create(qless, pipeline_module, "foo", {})
-        expect(batch).not_to be_complete
+        batch.meta['completed_at'] = Time.now.getutc.iso8601
+        expect(batch).to be_complete
       end
 
-      it 'returns false when there are pending jobs and completed jobs' do
+      it 'returns false if it lacks a completed_at timestamp' do
         batch = JobBatch.create(qless, pipeline_module, "foo", {})
-        batch.pending_job_jids << "a"
-        batch.completed_job_jids << "b"
         expect(batch).not_to be_complete
       end
-
-      it 'returns true when there are only completed jobs' do
-        batch = JobBatch.create(qless, pipeline_module, "foo", {})
-        batch.completed_job_jids << "b"
-        expect(batch).to be_complete
-      end
     end
 
     describe "#pending_qless_jobs" do
@@ -742,7 +735,7 @@ def update_dependency(batch, name)
       end
 
       it 'returns true for a complete job batch' do
-        batch.completed_job_jids << "a"
+        batch.meta['completed_at'] = Time.now.getutc.iso8601
         expect(batch.in_terminal_state?).to be_true
       end