test: add fuzzing to the test suite (#1463)

As a part of #1298, we add fuzzing based on Go test's fuzzing support to the test suite

Makefile

@@ -56,6 +56,7 @@ GO_TEST_ARGS ?= -short
 # Run tests
 test: generate fmt vet manifests
 	go test $(GO_TEST_ARGS) ./... -coverprofile cover.out
+	go test -fuzz=Fuzz -fuzztime=10s -run=Fuzz* ./controllers
 
 test-with-deps: kube-apiserver etcd kubectl
 	# See https://pkg.go.dev/sigs.k8s.io/controller-runtime/pkg/envtest#pkg-constants

controllers/schedule_test.go

@@ -605,3 +605,13 @@ func parseAndMatchRecurringPeriod(now time.Time, start, end, frequency, until st
 
 	return MatchSchedule(now, startTime, endTime, RecurrenceRule{Frequency: frequency, UntilTime: untilTime})
 }
+
+func FuzzMatchSchedule(f *testing.F) {
+	start := time.Now()
+	end := time.Now()
+	now := time.Now()
+	f.Fuzz(func(t *testing.T, freq string) {
+		// Verify that it never panics
+		_, _, _ = MatchSchedule(now, start, end, RecurrenceRule{Frequency: freq})
+	})
+}