clientv3: translate Snapshot API gRPC status error

[gyuho]

To be consistent with other APIs.

Related discussion #9024 (comment).

[fanminshi]

I don't think it is needed to write data cluster. this tests should care about about context canceled and deadline exceeded.

[gyuho]

We need test canceling the inflight snapshot stream. Without data, it's hard to simulate concurrent context cancel while snapshot is in progress. This manual mvcc writes give us about >1 second window where we can inject concurrent context cancel.

[fanminshi]

we can use ioutil.Discard instead.

[gyuho]

Good idea. Will change.

[fanminshi]

I was able to shorten the test with suggestions above to the following:

func TestMaintenanceSnapshotError(t *testing.T) {
	defer testutil.AfterTest(t)

	clus := integration.NewClusterV3(t, &integration.ClusterConfig{Size: 1})
	defer clus.Terminate(t)

	// reading snapshot with canceled context should error out
	ctx, cancel := context.WithCancel(context.Background())
	rc1, err := clus.RandClient().Snapshot(ctx)
	if err != nil {
		t.Fatal(err)
	}
	defer rc1.Close()

	cancel()
	_, err = io.Copy(ioutil.Discard, rc1)
	if err != context.Canceled {
		t.Errorf("expected %v, got %v", context.Canceled, err)
	}

	// reading snapshot with deadline exceeded should error out
	ctx, cancel = context.WithTimeout(context.Background(), 100*time.Millisecond)
	defer cancel()
	rc2, err := clus.RandClient().Snapshot(ctx)
	if err != nil {
		t.Fatal(err)
	}
	defer rc2.Close()

	time.Sleep(200 * time.Millisecond)

	_, err = io.Copy(ioutil.Discard, rc2)
	if err != nil && err != context.DeadlineExceeded {
		t.Errorf("expected %v, got %v", context.DeadlineExceeded, err)
	}
}

[fanminshi]

also prefer small timeout. so test runs faster. i suggest 100ms.

[xiang90]

lgtm

[fanminshi]

lgtm