# Source file src/internal/fuzz/queue_test.go

```     1  // Copyright 2021 The Go Authors. All rights reserved.
2  // Use of this source code is governed by a BSD-style
4
5  package fuzz
6
7  import "testing"
8
9  func TestQueue(t *testing.T) {
10  	// Zero valued queue should have 0 length and capacity.
11  	var q queue
12  	if n := q.len; n != 0 {
13  		t.Fatalf("empty queue has len %d; want 0", n)
14  	}
15  	if n := q.cap(); n != 0 {
16  		t.Fatalf("empty queue has cap %d; want 0", n)
17  	}
18
19  	// As we add elements, len should grow.
20  	N := 32
21  	for i := 0; i < N; i++ {
22  		q.enqueue(i)
23  		if n := q.len; n != i+1 {
24  			t.Fatalf("after adding %d elements, queue has len %d", i, n)
25  		}
26  		if v, ok := q.peek(); !ok {
27  			t.Fatalf("couldn't peek after adding %d elements", i)
28  		} else if v.(int) != 0 {
29  			t.Fatalf("after adding %d elements, peek is %d; want 0", i, v)
30  		}
31  	}
32
33  	// As we remove and add elements, len should shrink and grow.
34  	// We should also remove elements in the same order they were added.
35  	want := 0
36  	for _, r := range []int{1, 2, 3, 5, 8, 13, 21} {
37  		s := make([]int, 0, r)
38  		for i := 0; i < r; i++ {
39  			if got, ok := q.dequeue(); !ok {
40  				t.Fatalf("after removing %d of %d elements, could not dequeue", i+1, r)
41  			} else if got != want {
42  				t.Fatalf("after removing %d of %d elements, got %d; want %d", i+1, r, got, want)
43  			} else {
44  				s = append(s, got.(int))
45  			}
46  			want = (want + 1) % N
47  			if n := q.len; n != N-i-1 {
48  				t.Fatalf("after removing %d of %d elements, len is %d; want %d", i+1, r, n, N-i-1)
49  			}
50  		}
51  		for i, v := range s {
52  			q.enqueue(v)
53  			if n := q.len; n != N-r+i+1 {
54  				t.Fatalf("after adding back %d of %d elements, len is %d; want %d", i+1, r, n, n-r+i+1)
55  			}
56  		}
57  	}
58  }
59
```

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