Fix lint issues

Author: ivanahuckova

pkg/googlesheets/googlesheets.go

@@ -9,7 +9,6 @@ import (
 	"time"
 
 	"github.com/grafana/google-sheets-datasource/pkg/models"
-	"golang.org/x/oauth2"
 
 	"github.com/araddon/dateparse"
 	"github.com/davecgh/go-spew/spew"
@@ -18,6 +17,7 @@ import (
 	"github.com/grafana/grafana-plugin-sdk-go/data"
 	"github.com/grafana/grafana-plugin-sdk-go/experimental/errorsource"
 	"github.com/patrickmn/go-cache"
+	"golang.org/x/oauth2"
 	"google.golang.org/api/googleapi"
 	"google.golang.org/api/sheets/v4"
 )
@@ -94,10 +94,13 @@ func (gs *GoogleSheets) GetSpreadsheets(ctx context.Context, config models.Datas
 func (gs *GoogleSheets) getSheetData(client client, qm *models.QueryModel) (*sheets.GridData, map[string]any, error) {
 	cacheKey := qm.Spreadsheet + qm.Range
 	if item, expires, found := gs.Cache.GetWithExpiration(cacheKey); found && qm.CacheDurationSeconds > 0 {
-		return item.(*sheets.GridData), map[string]any{
-			"hit":     true,
-			"expires": expires.Unix(),
-		}, nil
+		if gridData, ok := item.(*sheets.GridData); ok {
+			return gridData, map[string]any{
+				"hit":     true,
+				"expires": expires.Unix(),
+			}, nil
+		} 
+		return nil, nil, errors.New("invalid cache item not type of *sheets.GridData")
 	}
 
 	result, err := client.GetSpreadsheet(qm.Spreadsheet, qm.Range, true)

pkg/googlesheets/googlesheets_test.go

@@ -29,7 +29,10 @@ type fakeClient struct {
 
 func (f *fakeClient) GetSpreadsheet(spreadSheetID string, sheetRange string, includeGridData bool) (*sheets.Spreadsheet, error) {
 	args := f.Called(spreadSheetID, sheetRange, includeGridData)
-	return args.Get(0).(*sheets.Spreadsheet), args.Error(1)
+	if spreadsheet, ok := args.Get(0).(*sheets.Spreadsheet); ok {
+		return spreadsheet, args.Error(1)
+	}
+	return nil, args.Error(1)
 }
 
 func loadTestSheet(path string) (*sheets.Spreadsheet, error) {
@@ -281,7 +284,8 @@ func TestGooglesheets(t *testing.T) {
 		})
 
 		t.Run("meta warnings field is populated correctly", func(t *testing.T) {
-			warnings := meta["warnings"].([]string)
+			warnings, ok := meta["warnings"].([]string)
+			require.True(t, ok)
 			assert.Equal(t, 3, len(warnings))
 			assert.Equal(t, "Multiple data types found in column \"MixedDataTypes\". Using string data type", warnings[0])
 			assert.Equal(t, "Multiple units found in column \"MixedUnits\". Formatted value will be used", warnings[1])