You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: slippy_test.go
    path of file: ./repos/tegola/cmd/tegola/cmd/cache
    
    the code of the file until where you have to start completion: package cache

import (
	"testing"

	"github.com/go-spatial/geom/slippy"
)

func TestRangeFamilyAt(t *testing.T) {
	type coord struct {
		z, x, y uint
	}

	type tcase struct {
		tile     *slippy.Tile
		zoomAt   uint
		expected []coord
	}

	isIn := func(arr []coord, c coord) bool {
		for _, v := range arr {
			if v == c {
				return true
			}
		}

		return false
	}

	fn := func(tc tcase) func(t *testing.T) {
		return func(t *testing.T) {

			coordList := make([]coord, 0, len(tc.expected))
			rangeFamilyAt(tc.tile, tc.zoomAt, func(tile *slippy.Tile) error {
				z, x, y := tile.ZXY()
				c := coord{z, x, y}

				coordList = append(coordList, c)

				return nil
			})

			if len(coordList) != len(tc.expected) {
				t.Fatalf("coordinate list length, expected %d, got %d: %v \n\n %v", len(tc.expected), len(coordList), tc.expected, coordList)
			}

			for _, v := range tc.expected {
				if !isIn(coordList, v) {
					t.Logf("coordinates: %v", coordList)
					t.Fatalf("coordinate exists, expected %v,  got missing", v)
				}
			}

		}
	}

	testcases := map[string]tcase{
		"children 1": {
			tile:   slippy.NewTile(0, 0, 0),
			zoomAt: 1,
			expected: []coord{
				{1, 0, 0},
				{1, 0, 1},
				{1, 1, 0},
				{1, 1, 1},
			},
		},
		"children 2": {
			tile:   slippy.NewTile(8, 3, 5),
			zoomAt: 10,
			expected: []coord{
				{10, 12, 20},
				{10, 12, 21},
				{10, 12, 22},
				{10, 12, 23},
				//
				{10, 13, 20},
				{10, 13, 21},
				{10, 13, 22},
				{10, 13, 23},
				//
				{10, 14, 20},
				{10, 14, 21},
				{10, 14, 22},
				{10, 14, 23},
				//
				{10, 15, 20},
				{10, 15, 21},
				{10, 15, 22},
				{10, 15, 23},
			},
		},
		"parent 1": {
			tile:   slippy.NewTile(1, 0, 0),
			zoomAt: 0,
			expected: []coord{
				{0, 0, 0},
			},
		},
		"parent 2": {
			tile:   
    
func TestRangeFamilyAt(t *testing.T) {
	type coord struct {
		z, x, y uint
	}

	type tcase struct {
		tile     *slippy.Tile
		zoomAt   uint
		expected []coord
	}

	isIn := func(arr []coord, c coord) bool {
		for _, v := range arr {
			if v == c {
				return true
			}
		}

		return false
	}

	fn := func(tc tcase) func(t *testing.T) {
		return func(t *testing.T) {

			coordList := make([]coord, 0, len(tc.expected))
			rangeFamilyAt(tc.tile, tc.zoomAt, func(tile *slippy.Tile) error {
				z, x, y := tile.ZXY()
				c := coord{z, x, y}

				coordList = append(coordList, c)

				return nil
			})

			if len(coordList) != len(tc.expected) {
				t.Fatalf("coordinate list length, expected %d, got %d: %v \n\n %v", len(tc.expected), len(coordList), tc.expected, coordList)
			}

			for _, v := range tc.expected {
				if !isIn(coordList, v) {
					t.Logf("coordinates: %v", coordList)
					t.Fatalf("coordinate exists, expected %v,  got missing", v)
				}
			}

		}
	}

	testcases := map[string]tcase{
		"children 1": {
			tile:   slippy.NewTile(0, 0, 0),
			zoomAt: 1,
			expected: []coord{
				{1, 0, 0},
				{1, 0, 1},
				{1, 1, 0},
				{1, 1, 1},
			},
		},
		"children 2": {
			tile:   slippy.NewTile(8, 3, 5),
			zoomAt: 10,
			expected: []coord{
				{10, 12, 20},
				{10, 12, 21},
				{10, 12, 22},
				{10, 12, 23},
				//
				{10, 13, 20},
				{10, 13, 21},
				{10, 13, 22},
				{10, 13, 23},
				//
				{10, 14, 20},
				{10, 14, 21},
				{10, 14, 22},
				{10, 14, 23},
				//
				{10, 15, 20},
				{10, 15, 21},
				{10, 15, 22},
				{10, 15, 23},
			},
		},
		"parent 1": {
			tile:   slippy.NewTile(1, 0, 0),
			zoomAt: 0,
			expected: []coord{
				{0, 0, 0},
			},
		},
		"parent 2": {
			tile:   slippy.NewTile(3, 3, 5),
			zoomAt: 1,
			expected: []coord{
				{1, 0, 1},
			},
		},
	}

	for name, tc := range testcases {
		t.Run(name, fn(tc))
	}
}