diff --git a/controllers/cron_test.go b/controllers/cron_test.go
new file mode 100644
index 0000000..43e2e84
--- /dev/null
+++ b/controllers/cron_test.go
@@ -0,0 +1,81 @@
+/*
+Copyright 2021 Daisuke Taniwaki.
+
+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 controllers
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"k8s.io/apimachinery/pkg/types"
+)
+
+func TestCron(t *testing.T) {
+	cron := NewCron()
+	err := cron.Add(types.NamespacedName{Name: "foo", Namespace: "ns"}, "patch-1", "0 * * * *", &CronContext{
+		reconciler: nil,
+		cronhpa:    nil,
+		patchName:  "patch-1",
+	})
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	err = cron.Add(types.NamespacedName{Name: "foo", Namespace: "ns"}, "patch-2", "0 * * * *", &CronContext{
+		reconciler: nil,
+		cronhpa:    nil,
+		patchName:  "patch-2",
+	})
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	err = cron.Add(types.NamespacedName{Name: "foo", Namespace: "ns"}, "patch-3", "0 * * * *", &CronContext{
+		reconciler: nil,
+		cronhpa:    nil,
+		patchName:  "patch-3",
+	})
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	err = cron.Add(types.NamespacedName{Name: "bar", Namespace: "ns"}, "patch-4", "0 * * * *", &CronContext{
+		reconciler: nil,
+		cronhpa:    nil,
+		patchName:  "patch-4",
+	})
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	resourceEntry := cron.ListResourceEntry(types.NamespacedName{Name: "foo", Namespace: "ns"})
+	assert.Equal(t, ResourceEntry{
+		"patch-1": 1,
+		"patch-2": 2,
+		"patch-3": 3,
+	}, resourceEntry)
+
+	cron.Remove(types.NamespacedName{Name: "foo", Namespace: "ns"}, "patch-1")
+	resourceEntry = cron.ListResourceEntry(types.NamespacedName{Name: "foo", Namespace: "ns"})
+	assert.Equal(t, ResourceEntry{
+		"patch-2": 2,
+		"patch-3": 3,
+	}, resourceEntry)
+	cron.Remove(types.NamespacedName{Name: "foo", Namespace: "ns"}, "paptch-1")
+
+	cron.RemoveResourceEntry(types.NamespacedName{Name: "foo", Namespace: "ns"})
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	resourceEntry = cron.ListResourceEntry(types.NamespacedName{Name: "foo", Namespace: "ns"})
+	assert.Equal(t, ResourceEntry{}, resourceEntry)
+}