Add pubsub package to handle robust publisher

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

pubsub/publisher_test.go

@@ -0,0 +1,63 @@
+package pubsub
+
+import (
+	"testing"
+	"time"
+)
+
+func TestSendToOneSub(t *testing.T) {
+	p := NewPublisher(100*time.Millisecond, 10)
+	c := p.Subscribe()
+
+	p.Publish("hi")
+
+	msg := <-c
+	if msg.(string) != "hi" {
+		t.Fatalf("expected message hi but received %v", msg)
+	}
+}
+
+func TestSendToMultipleSubs(t *testing.T) {
+	p := NewPublisher(100*time.Millisecond, 10)
+	subs := []chan interface{}{}
+	subs = append(subs, p.Subscribe(), p.Subscribe(), p.Subscribe())
+
+	p.Publish("hi")
+
+	for _, c := range subs {
+		msg := <-c
+		if msg.(string) != "hi" {
+			t.Fatalf("expected message hi but received %v", msg)
+		}
+	}
+}
+
+func TestEvictOneSub(t *testing.T) {
+	p := NewPublisher(100*time.Millisecond, 10)
+	s1 := p.Subscribe()
+	s2 := p.Subscribe()
+
+	p.Evict(s1)
+	p.Publish("hi")
+	if _, ok := <-s1; ok {
+		t.Fatal("expected s1 to not receive the published message")
+	}
+
+	msg := <-s2
+	if msg.(string) != "hi" {
+		t.Fatalf("expected message hi but received %v", msg)
+	}
+}
+
+func TestClosePublisher(t *testing.T) {
+	p := NewPublisher(100*time.Millisecond, 10)
+	subs := []chan interface{}{}
+	subs = append(subs, p.Subscribe(), p.Subscribe(), p.Subscribe())
+	p.Close()
+
+	for _, c := range subs {
+		if _, ok := <-c; ok {
+			t.Fatal("expected all subscriber channels to be closed")
+		}
+	}
+}