Fix for fetcher warning at server startup (prebid#1914)

Co-authored-by: Veronika Solovei <[email protected]>

stored_requests/config/config.go

@@ -166,6 +166,9 @@ func newFetcher(cfg *config.StoredRequests, client *http.Client, db *sql.DB) (fe
 	if cfg.Postgres.FetcherQueries.QueryTemplate != "" {
 		glog.Infof("Loading Stored %s data via Postgres.\nQuery: %s", cfg.DataType(), cfg.Postgres.FetcherQueries.QueryTemplate)
 		idList = append(idList, db_fetcher.NewFetcher(db, cfg.Postgres.FetcherQueries.MakeQuery))
+	} else if cfg.Postgres.CacheInitialization.Query != "" && cfg.Postgres.PollUpdates.Query != "" {
+		//in this case data will be loaded to cache via poll for updates event
+		idList = append(idList, empty_fetcher.EmptyFetcher{})
 	}
 	if cfg.HTTP.Endpoint != "" {
 		glog.Infof("Loading Stored %s data via HTTP. endpoint=%s", cfg.DataType(), cfg.HTTP.Endpoint)

stored_requests/config/config_test.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"context"
+	"database/sql"
 	"encoding/json"
 	"errors"
 	"net/http"
@@ -41,12 +42,79 @@ func isMemoryCacheType(cache stored_requests.CacheJSON) bool {
 }
 
 func TestNewEmptyFetcher(t *testing.T) {
-	fetcher := newFetcher(&config.StoredRequests{}, nil, nil)
-	if fetcher == nil {
-		t.Errorf("The fetcher should be non-nil, even with an empty config.")
+
+	type testCase struct {
+		config       *config.StoredRequests
+		emptyFetcher bool
+		description  string
 	}
-	if _, ok := fetcher.(empty_fetcher.EmptyFetcher); !ok {
-		t.Errorf("If the config is empty, and EmptyFetcher should be returned")
+	testCases := []testCase{
+		{
+			config:       &config.StoredRequests{},
+			emptyFetcher: true,
+			description:  "If the config is empty, an EmptyFetcher should be returned",
+		},
+		{
+			config: &config.StoredRequests{
+				Postgres: config.PostgresConfig{
+					CacheInitialization: config.PostgresCacheInitializer{
+						Query: "test query",
+					},
+					PollUpdates: config.PostgresUpdatePolling{
+						Query: "test poll query",
+					},
+					FetcherQueries: config.PostgresFetcherQueries{
+						QueryTemplate: "",
+					},
+				},
+			},
+			emptyFetcher: true,
+			description:  "If Postgres fetcher query is not defined, but Postgres Cache init query and Postgres update polling query are defined EmptyFetcher should be returned",
+		},
+		{
+			config: &config.StoredRequests{
+				Postgres: config.PostgresConfig{
+					CacheInitialization: config.PostgresCacheInitializer{
+						Query: "",
+					},
+					PollUpdates: config.PostgresUpdatePolling{
+						Query: "",
+					},
+					FetcherQueries: config.PostgresFetcherQueries{
+						QueryTemplate: "test fetcher query",
+					},
+				},
+			},
+			emptyFetcher: false,
+			description:  "If Postgres fetcher query is  defined, but Postgres Cache init query and Postgres update polling query are not defined not EmptyFetcher (DBFetcher) should be returned",
+		},
+		{
+			config: &config.StoredRequests{
+				Postgres: config.PostgresConfig{
+					CacheInitialization: config.PostgresCacheInitializer{
+						Query: "test cache query",
+					},
+					PollUpdates: config.PostgresUpdatePolling{
+						Query: "test poll query",
+					},
+					FetcherQueries: config.PostgresFetcherQueries{
+						QueryTemplate: "test fetcher query",
+					},
+				},
+			},
+			emptyFetcher: false,
+			description:  "If Postgres fetcher query is  defined and Postgres Cache init query and Postgres update polling query are  defined not EmptyFetcher (DBFetcher) should be returned",
+		},
+	}
+
+	for _, test := range testCases {
+		fetcher := newFetcher(test.config, nil, &sql.DB{})
+		assert.NotNil(t, fetcher, "The fetcher should be non-nil.")
+		if test.emptyFetcher {
+			assert.Equal(t, empty_fetcher.EmptyFetcher{}, fetcher, "Empty fetcher should be returned")
+		} else {
+			assert.NotEqual(t, empty_fetcher.EmptyFetcher{}, fetcher)
+		}
 	}
 }