Squashed commit of the following:

commit 10456b1e9240886432f565dd17689080bbb133b9
Merge: 312c1a9bdf8 a5f4627857b
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Thu Nov 29 14:33:21 2018 +0900

    Merge branch 'master-ce' into add-counter-for-trace-chunks

commit 312c1a9bdf8efc45c3fed5ff50f05cc589bbb4ed
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Wed Nov 28 20:06:18 2018 +0900

    Fix coding offence

commit e397cc2ccc1b2cf7f8b3558b8fa81fe2aa0ab366
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Wed Nov 28 14:40:24 2018 +0900

    Fix tracking archive failure

1 files changed, 39 insertions, 0 deletions

diff --git a/spec/services/ci/archive_trace_service_spec.rb b/spec/services/ci/archive_trace_service_spec.rb
new file mode 100644
index 00000000000..6389d7a921f
--- /dev/null
+++ b/spec/services/ci/archive_trace_service_spec.rb
@@ -0,0 +1,39 @@
+require 'spec_helper'
+
+describe Ci::ArchiveTraceService, '#execute' do
+  subject { described_class.new.execute(job) }
+
+  context 'when job is finished' do
+    let(:job) { create(:ci_build, :success, :trace_live) }
+
+    it 'creates an archived trace' do
+      expect { subject }.not_to raise_error
+
+      expect(job.reload.job_artifacts_trace).to be_exist
+    end
+  end
+
+  context 'when job is running' do
+    let(:job) { create(:ci_build, :running, :trace_live) }
+
+    it 'increments Prometheus counter, sends crash report to Sentry and ignore an error for continuing to archive' do
+      expect(Gitlab::Sentry)
+        .to receive(:track_exception)
+        .with(::Gitlab::Ci::Trace::ArchiveError,
+              issue_url: 'https://gitlab.com/gitlab-org/gitlab-ce/issues/51502',
+              extra: { job_id: job.id } ).once
+
+      expect(Rails.logger)
+        .to receive(:error)
+        .with("Failed to archive trace. id: #{job.id} message: Job is not finished yet")
+        .and_call_original
+
+      expect(Gitlab::Metrics)
+        .to receive(:counter)
+        .with(:job_trace_archive_failed_total, "Counter of failed attempts of trace archiving")
+        .and_call_original
+
+      expect { subject }.not_to raise_error
+    end
+  end
+end