Chore: Use interfaces where possible (#26392)

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/services/alerting/alerting_usage.go

@@ -3,7 +3,6 @@ package alerting
 import (
 	"encoding/json"
 
-	"github.com/grafana/grafana/pkg/components/simplejson"
 	"github.com/grafana/grafana/pkg/models"
 )
 
@@ -75,7 +74,7 @@ func (ae *AlertEngine) mapRulesToUsageStats(rules []*models.Alert) (DatasourceAl
 	return result, nil
 }
 
-func (ae *AlertEngine) parseAlertRuleModel(settings *simplejson.Json) ([]int64, error) {
+func (ae *AlertEngine) parseAlertRuleModel(settings json.Marshaler) ([]int64, error) {
 	datasourceIDs := []int64{}
 	model := alertJSONModel{}
 
@@ -85,7 +84,7 @@ func (ae *AlertEngine) parseAlertRuleModel(settings *simplejson.Json) ([]int64,
 
 	bytes, err := settings.MarshalJSON()
 	if err != nil {
-		return datasourceIDs, err
+		return nil, err
 	}
 
 	err = json.Unmarshal(bytes, &model)

pkg/services/alerting/alerting_usage_test.go

@@ -1,6 +1,7 @@
 package alerting
 
 import (
+	"encoding/json"
 	"io/ioutil"
 	"testing"
 
@@ -95,8 +96,7 @@ func TestParsingAlertRuleSettings(t *testing.T) {
 			shouldErr: require.NoError,
 		},
 		{
-			name:      "can parse blank content",
-			file:      "testdata/settings/invalid_format.json",
+			name:      "can handle nil content",
 			expected:  []int64{},
 			shouldErr: require.NoError,
 		},
@@ -108,12 +108,16 @@ func TestParsingAlertRuleSettings(t *testing.T) {
 
 	for _, tc := range tcs {
 		t.Run(tc.name, func(t *testing.T) {
-			content, err := ioutil.ReadFile(tc.file)
-			require.NoError(t, err, "expected to be able to read file")
+			var settings json.Marshaler
+			if tc.file != "" {
+				content, err := ioutil.ReadFile(tc.file)
+				require.NoError(t, err, "expected to be able to read file")
 
-			j, _ := simplejson.NewJson(content)
+				settings, err = simplejson.NewJson(content)
+				require.NoError(t, err)
+			}
 
-			result, err := ae.parseAlertRuleModel(j)
+			result, err := ae.parseAlertRuleModel(settings)
 
 			tc.shouldErr(t, err)
 			diff := cmp.Diff(tc.expected, result)

pkg/services/alerting/extractor.go

@@ -1,6 +1,7 @@
 package alerting
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"time"
@@ -64,7 +65,7 @@ func findPanelQueryByRefID(panel *simplejson.Json, refID string) *simplejson.Jso
 	return nil
 }
 
-func copyJSON(in *simplejson.Json) (*simplejson.Json, error) {
+func copyJSON(in json.Marshaler) (*simplejson.Json, error) {
 	rawJSON, err := in.MarshalJSON()
 	if err != nil {
 		return nil, err