fix(pkg/sshd/circuit_test.go): add concurrency test for the circuit

Author: Aaron Schlesinger

pkg/sshd/circuit_test.go

@@ -1,9 +1,21 @@
 package sshd
 
 import (
+	"math/rand"
+	"sync"
+	"sync/atomic"
 	"testing"
+	"time"
 )
 
+const (
+	numConcurrents = 1000
+)
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
 func TestOpenCloseSerial(t *testing.T) {
 	c := NewCircuit()
 	if c.State() != OpenState {
@@ -24,5 +36,25 @@ func TestOpenCloseSerial(t *testing.T) {
 }
 
 func TestOpenCloseConcurrent(t *testing.T) {
-
+	c := NewCircuit()
+	var wg sync.WaitGroup
+	state := uint32(0)
+	for i := 0; i < numConcurrents; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			r := rand.Int() % 2
+			if r == 0 {
+				c.Open()
+				atomic.StoreUint32(&state, OpenState.toUint32())
+			} else {
+				c.Close()
+				atomic.StoreUint32(&state, ClosedState.toUint32())
+			}
+		}(i)
+	}
+	wg.Wait()
+	if state != c.State().toUint32() {
+		t.Fatalf("expected state %d wasn't equal to actual %d", state, c.State().toUint32())
+	}
 }