Add tests to diode

server/events/diode.go

@@ -20,6 +20,14 @@ func (d *diode) set(data message) {
 	d.d.Set(diodes.GenericDataType(&data))
 }
 
+func (d *diode) tryNext() (*message, bool) {
+	data, ok := d.d.TryNext()
+	if !ok {
+		return nil, ok
+	}
+	return (*message)(data), true
+}
+
 func (d *diode) next() *message {
 	data := d.d.Next()
 	return (*message)(data)

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())
+	})
+})

server/events/sse.go

@@ -148,7 +148,7 @@ func (b *broker) subscribe(r *http.Request) client {
 		address:   r.RemoteAddr,
 		userAgent: r.UserAgent(),
 	}
-	c.diode = newDiode(r.Context(), 1000, diodes.AlertFunc(func(missed int) {
+	c.diode = newDiode(r.Context(), 1024, diodes.AlertFunc(func(missed int) {
 		log.Trace("Dropped SSE events", "client", c.String(), "missed", missed)
 	}))