api: fix wrong pageCount in /list endpoints (#1813)

internal/core/api.go

@@ -84,7 +84,10 @@ func paginate2(itemsPtr interface{}, itemsPerPage int, page int) int {
 		return 0
 	}
 
-	pageCount := (itemsLen / itemsPerPage) + 1
+	pageCount := (itemsLen / itemsPerPage)
+	if (itemsLen % itemsPerPage) != 0 {
+		pageCount++
+	}
 
 	min := page * itemsPerPage
 	if min >= itemsLen {

internal/core/api_test.go

@@ -78,6 +78,38 @@ func httpRequest(method string, ur string, in interface{}, out interface{}) erro
 	return json.NewDecoder(res.Body).Decode(out)
 }
 
+func TestPagination(t *testing.T) {
+	items := make([]int, 5)
+	for i := 0; i < 5; i++ {
+		items[i] = i
+	}
+
+	pageCount, err := paginate(&items, "1", "1")
+	require.NoError(t, err)
+	require.Equal(t, 5, pageCount)
+	require.Equal(t, []int{1}, items)
+
+	items = make([]int, 5)
+	for i := 0; i < 5; i++ {
+		items[i] = i
+	}
+
+	pageCount, err = paginate(&items, "3", "2")
+	require.NoError(t, err)
+	require.Equal(t, 2, pageCount)
+	require.Equal(t, []int{4}, items)
+
+	items = make([]int, 6)
+	for i := 0; i < 6; i++ {
+		items[i] = i
+	}
+
+	pageCount, err = paginate(&items, "3", "3")
+	require.NoError(t, err)
+	require.Equal(t, 2, pageCount)
+	require.Equal(t, []int{5}, items)
+}
+
 func TestAPIConfigGet(t *testing.T) {
 	// since the HTTP server is created and deleted multiple times,
 	// we can't reuse TCP connections.