Add tests to diode

server/events/diodo_test.go

@@ -0,0 +1,51 @@
+package events
+
+import (
+	"context"
+
+	"code.cloudfoundry.org/go-diodes"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("diode", func() {
+	var diode *diode
+	var ctx context.Context
+	var ctxCancel context.CancelFunc
+	var missed int
+
+	BeforeEach(func() {
+		missed = 0
+		ctx, ctxCancel = context.WithCancel(context.Background())
+		diode = newDiode(ctx, 2, diodes.AlertFunc(func(m int) { missed = m }))
+	})
+
+	It("enqueues the data correctly", func() {
+		diode.set(message{Data: "1"})
+		diode.set(message{Data: "2"})
+		Expect(diode.next()).To(Equal(&message{Data: "1"}))
+		Expect(diode.next()).To(Equal(&message{Data: "2"}))
+		Expect(missed).To(BeZero())
+	})
+
+	It("drops messages when diode is full", func() {
+		diode.set(message{Data: "1"})
+		diode.set(message{Data: "2"})
+		diode.set(message{Data: "3"})
+		next, ok := diode.tryNext()
+		Expect(ok).To(BeTrue())
+		Expect(next).To(Equal(&message{Data: "3"}))
+
+		_, ok = diode.tryNext()
+		Expect(ok).To(BeFalse())
+
+		Expect(missed).To(Equal(2))
+	})
+
+	It("returns nil when diode is empty and the context is canceled", func() {
+		diode.set(message{Data: "1"})
+		ctxCancel()
+		Expect(diode.next()).To(Equal(&message{Data: "1"}))
+		Expect(diode.next()).To(BeNil())
+	})
+})