test: add testcase for FIFO Queue in collection module (#1589)

cover the case of non-zero value for q.Header when q.Elements expands

core/collection/fifo_test.go

@@ -61,3 +61,41 @@ func TestPutMore(t *testing.T) {
 		assert.Equal(t, string(element), string(body.([]byte)))
 	}
 }
+
+func TestPutMoreWithHeaderNotZero(t *testing.T) {
+	elements := [][]byte{
+		[]byte("hello"),
+		[]byte("world"),
+		[]byte("again"),
+	}
+	queue := NewQueue(4)
+	for i := range elements {
+		queue.Put(elements[i])
+	}
+
+	// take 1
+	body, ok := queue.Take()
+	assert.True(t, ok)
+	element, ok := body.([]byte)
+	assert.True(t, ok)
+	assert.Equal(t, element, []byte("hello"))
+
+	// put more
+	queue.Put([]byte("b4"))
+	queue.Put([]byte("b5")) // will store in elements[0]
+	queue.Put([]byte("b6")) // cause expansion
+
+	results := [][]byte{
+		[]byte("world"),
+		[]byte("again"),
+		[]byte("b4"),
+		[]byte("b5"),
+		[]byte("b6"),
+	}
+
+	for _, element := range results {
+		body, ok := queue.Take()
+		assert.True(t, ok)
+		assert.Equal(t, string(element), string(body.([]byte)))
+	}
+}