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package resolver
import (
"strconv"
"testing"
)
func TestTopoSortEmpty(t *testing.T) {
sorted := topoSort(nil)
if len(sorted) != 0 {
t.Fatalf("expected empty slice, got %v", sorted)
}
}
func TestTopoSortSimple(t *testing.T) {
sorted := topoSort(map[string]map[string]struct{}{
"a": {"b": struct{}{}},
"b": {"c": struct{}{}},
})
if len(sorted) != 3 {
t.Fatalf("expected 3 items, got %d", len(sorted))
}
assertBefore(t, sorted, "c", "b")
assertBefore(t, sorted, "b", "a")
}
func TestTopoSortComplex(t *testing.T) {
sorted := topoSort(map[string]map[string]struct{}{
"a": {"b": struct{}{}, "c": struct{}{}},
"c": {"d": struct{}{}},
"f": {"g": struct{}{}, "h": struct{}{}},
"g": {},
"h": {},
})
if len(sorted) != 7 {
t.Fatalf("expected 7 items, got %d", len(sorted))
}
assertBefore(t, sorted, "g", "f")
assertBefore(t, sorted, "h", "f")
assertBefore(t, sorted, "d", "c")
assertBefore(t, sorted, "c", "a")
assertBefore(t, sorted, "b", "a")
}
func assertBefore(t *testing.T, sorted []string, x, y string) {
xi := strIndex(sorted, x)
if xi < 0 {
t.Fatalf("expected %q to be in result", x)
}
yi := strIndex(sorted, y)
if yi < 0 {
t.Fatalf("expected %q to be in result", y)
}
if xi >= yi {
t.Fatalf("expected %q to come before %q, got indexes %d and %d", x, y, xi, yi)
}
}
func strIndex(slice []string, s string) int {
for i, item := range slice {
if s == item {
return i
}
}
return -1
}
func TestTopoSortCycle(t *testing.T) {
sorted := topoSort(map[string]map[string]struct{}{
"a": {"b": struct{}{}, "c": struct{}{}},
"c": {"a": struct{}{}},
})
if len(sorted) != 3 {
t.Fatalf("expected 3 items, got %d", len(sorted))
}
assertBefore(t, sorted, "b", "a")
c := strIndex(sorted, "a")
if c < 0 {
t.Fatalf("expected %q to be in result", c)
}
}
func TestTopoSortLarge(t *testing.T) {
const num = 1000
graph := make(map[string]map[string]struct{})
for i := 0; i < num; i++ {
graph[strconv.Itoa(i)] = map[string]struct{}{strconv.Itoa(i + 1): {}}
}
graph[strconv.Itoa(num)] = map[string]struct{}{}
sorted := topoSort(graph)
if len(sorted) != num+1 {
t.Fatalf("expected %d items, got %d", num+1, len(sorted))
}
for i := 0; i < num+1; i++ {
expected := num - i
if sorted[i] != strconv.Itoa(expected) {
t.Fatalf("expected %d to be at index %d, got %s", num-1, i, sorted[i])
}
}
}
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