Alerting: recalculate EndsAt (#35830)

* setEndsAt

* one more test case

* add should clause to tests

pkg/services/ngalert/state/state_test.go

@@ -4,6 +4,8 @@ import (
 	"testing"
 	"time"
 
+	ngmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
+
 	"github.com/grafana/grafana/pkg/services/ngalert/eval"
 
 	"github.com/stretchr/testify/assert"
@@ -73,3 +75,93 @@ func TestNeedsSending(t *testing.T) {
 		})
 	}
 }
+
+func TestSetEndsAt(t *testing.T) {
+	evaluationTime, _ := time.Parse("2006-01-02", "2021-03-25")
+	testCases := []struct {
+		name       string
+		expected   time.Time
+		testState  *State
+		testRule   *ngmodels.AlertRule
+		testResult eval.Result
+	}{
+		{
+			name:      "For: unset Interval: 10s EndsAt should be evaluation time + 2X IntervalSeconds",
+			expected:  evaluationTime.Add(20 * time.Second),
+			testState: &State{},
+			testRule: &ngmodels.AlertRule{
+				IntervalSeconds: 10,
+			},
+			testResult: eval.Result{
+				EvaluatedAt: evaluationTime,
+			},
+		},
+		{
+			name:      "For: 0s Interval: 10s EndsAt should be evaluation time + 2X IntervalSeconds",
+			expected:  evaluationTime.Add(20 * time.Second),
+			testState: &State{},
+			testRule: &ngmodels.AlertRule{
+				For:             0 * time.Second,
+				IntervalSeconds: 10,
+			},
+			testResult: eval.Result{
+				EvaluatedAt: evaluationTime,
+			},
+		},
+		{
+			name:      "For: 1s Interval: 10s EndsAt should be evaluation time + 2X IntervalSeconds",
+			expected:  evaluationTime.Add(20 * time.Second),
+			testState: &State{},
+			testRule: &ngmodels.AlertRule{
+				For:             0 * time.Second,
+				IntervalSeconds: 10,
+			},
+			testResult: eval.Result{
+				EvaluatedAt: evaluationTime,
+			},
+		},
+		{
+			name:      "For: 10s Interval: 10s EndsAt should be evaluation time + 2X IntervalSeconds",
+			expected:  evaluationTime.Add(20 * time.Second),
+			testState: &State{},
+			testRule: &ngmodels.AlertRule{
+				For:             10 * time.Second,
+				IntervalSeconds: 10,
+			},
+			testResult: eval.Result{
+				EvaluatedAt: evaluationTime,
+			},
+		},
+		{
+			name:      "For: 11s Interval: 10s EndsAt should be evaluation time + For duration",
+			expected:  evaluationTime.Add(11 * time.Second),
+			testState: &State{},
+			testRule: &ngmodels.AlertRule{
+				For:             11 * time.Second,
+				IntervalSeconds: 10,
+			},
+			testResult: eval.Result{
+				EvaluatedAt: evaluationTime,
+			},
+		},
+		{
+			name:      "For: 20s Interval: 10s EndsAt should be evaluation time + For duration",
+			expected:  evaluationTime.Add(20 * time.Second),
+			testState: &State{},
+			testRule: &ngmodels.AlertRule{
+				For:             20 * time.Second,
+				IntervalSeconds: 10,
+			},
+			testResult: eval.Result{
+				EvaluatedAt: evaluationTime,
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			tc.testState.setEndsAt(tc.testRule, tc.testResult)
+			assert.Equal(t, tc.expected, tc.testState.EndsAt)
+		})
+	}
+}