initial structure

queue/queue_test.go

@@ -0,0 +1,49 @@
+package queue
+
+import (
+	"container/heap"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestQueue(t *testing.T) {
+	// Some items and their priorities.
+	items := map[string]int64{
+		"id0": 2,
+		"id1": 5,
+		"id2": 4,
+	}
+
+	// Create a priority queue, put the items in it, and
+	// establish the priority queue (heap) invariants.
+	pq := make(PriorityQueue, len(items))
+	i := 0
+	for value, priority := range items {
+		pq[i] = &Item{
+			value:    value,
+			priority: priority,
+			index:    i,
+		}
+		i++
+	}
+	heap.Init(&pq)
+
+	assert.Equal(t, pq.Look().value, "id0")
+
+	// Insert a new item and then modify its priority.
+	item := &Item{
+		value:    "id3",
+		priority: 3,
+	}
+	heap.Push(&pq, item)
+	pq.update(item, item.value, 1)
+	assert.Equal(t, pq.Look().value, "id3")
+
+	// Take the items out; they arrive in increasing priority order.
+	for pq.Len() > 0 {
+		_ = heap.Pop(&pq).(*Item)
+		// fmt.Println("priority", item.priority, ":", item.value)
+	}
+	assert.Nil(t, pq.Look())
+}