Extract queryData function

pkg/opensearch/opensearch.go

@@ -60,17 +60,22 @@ func (ds *OpenSearchDatasource) CheckHealth(ctx context.Context, req *backend.Ch
 // The QueryDataResponse contains a map of RefID to the response for each query, and each response
 // contains Frames ([]*Frame).
 func (ds *OpenSearchDatasource) QueryData(ctx context.Context, req *backend.QueryDataRequest) (*backend.QueryDataResponse, error) {
-	if len(req.Queries) == 0 {
+	return queryData(ctx, req.Queries, req.PluginContext.DataSourceInstanceSettings, ds.httpClient)
+}
+
+// separate function to allow testing the whole transformation and query flow
+func queryData(ctx context.Context, queries []backend.DataQuery, dsSettings *backend.DataSourceInstanceSettings, httpClient *http.Client) (*backend.QueryDataResponse, error) {
+	if len(queries) == 0 {
 		return nil, fmt.Errorf("query contains no queries")
 	}
 
-	timeRange := req.Queries[0].TimeRange
-	osClient, err := client.NewClient(ctx, req.PluginContext.DataSourceInstanceSettings, ds.httpClient, &timeRange)
+	timeRange := queries[0].TimeRange
+	osClient, err := client.NewClient(ctx, dsSettings, httpClient, &timeRange)
 	if err != nil {
 		return nil, err
 	}
 
-	query := newTimeSeriesQuery(osClient, req.Queries, intervalCalculator)
+	query := newTimeSeriesQuery(osClient, queries, intervalCalculator)
 	response, err := wrapError(query.execute())
 	return response, err
 }