Add merge alert test

types/types.go

@@ -183,7 +183,7 @@ func (a *Alert) Merge(o *Alert) *Alert {
 		res.StartsAt = a.StartsAt
 	}
 
-	// An non-timeout resolved timestamp always rules.
+	// A non-timeout resolved timestamp always rules.
 	// The latest explicit resolved timestamp wins.
 	if a.EndsAt.After(o.EndsAt) && !a.Timeout {
 		res.EndsAt = a.EndsAt

types/types_test.go

@@ -0,0 +1,63 @@
+// Copyright 2015 Prometheus Team
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package types
+
+import (
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/prometheus/common/model"
+)
+
+func TestAlertMerge(t *testing.T) {
+	now := time.Now()
+
+	pairs := []struct {
+		A, B, Res *Alert
+	}{
+		{
+			A: &Alert{
+				Alert: model.Alert{
+					StartsAt: now.Add(-time.Minute),
+					EndsAt:   now.Add(2 * time.Minute),
+				},
+				UpdatedAt: now,
+				Timeout:   true,
+			},
+			B: &Alert{
+				Alert: model.Alert{
+					StartsAt: now.Add(-time.Minute),
+					EndsAt:   now.Add(3 * time.Minute),
+				},
+				UpdatedAt: now.Add(time.Minute),
+				Timeout:   true,
+			},
+			Res: &Alert{
+				Alert: model.Alert{
+					StartsAt: now.Add(-time.Minute),
+					EndsAt:   now.Add(3 * time.Minute),
+				},
+				UpdatedAt: now.Add(time.Minute),
+				Timeout:   true,
+			},
+		},
+	}
+
+	for _, p := range pairs {
+		if res := p.A.Merge(p.B); !reflect.DeepEqual(p.Res, res) {
+			t.Errorf("unexpected merged alert %#v", res)
+		}
+	}
+}