feat(18.1-01): task 3 flat reorder on the server

- config_reorder.yaml without parentColumn on a record with no parent_id
  column compiles as a flat (WinterCMS Sortable) reorder; maxDepth above 0
  on it fails boot, an explicit parentColumn still means a tree
- ListReorder.Flat and AdminReorderTree.Flat (flat, omitempty); flat nodes
  carry parent_id null, a save writes only the sort column, a parent is a
  422 on nodes (reorder.flat_parent); 409 and duplicate rules unchanged
- swag descriptions, OpenAPI and schema.d.ts regenerated
- acme.catalog badges reorder fixture, TestReorderFlatCompile and
  TestReorderFlatSmoke; docs Flat reorder section and cabana README

modules/cabana/reorder_flat_test.go

@@ -0,0 +1,79 @@
+package cabana_test
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"git.golem15.com/golem15/summercms/modules/cabana"
+	"git.golem15.com/golem15/summercms/modules/party"
+)
+
+// Smoke tests of the flat (WinterCMS Sortable) reorder (Phase 18.1 D-17),
+// Docker-free: the inference rule and the flat flag. The Postgres routes are
+// TestReorderFlatSmoke in catalog_smoke_test.go. Full unit coverage is plan
+// 06. No application names appear in framework tests.
+
+// TestReorderFlatCompile pins the flat inference: a config_reorder.yaml
+// without parentColumn on a record without a parent_id column compiles as
+// flat and the list schema says so; maxDepth on it and an explicit
+// parentColumn that is not a column fail boot; the tree fixture still
+// compiles as a tree whose list schema carries no flat key.
+func TestReorderFlatCompile(t *testing.T) {
+	const cfg = "controllers/badges/config_reorder.yaml"
+	list, err := cabana.CompiledListSchema([]party.Plugin{catalogFSPlugin{fsys: catalogOverlay(t, nil)}}, "acme.catalog.badges")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if list.Reorder == nil || !list.Reorder.Flat || list.Reorder.Title != "Reorder badges" {
+		t.Fatalf("badges reorder = %+v", list.Reorder)
+	}
+	raw, err := json.Marshal(list.Reorder)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(string(raw), `"flat":true`) {
+		t.Fatalf("flat list schema JSON: %s", raw)
+	}
+	if err := activateCatalog(t, catalogFSPlugin{fsys: catalogOverlay(t, nil)}); err != nil {
+		t.Fatalf("catalog boot: %v", err)
+	}
+
+	src := catalogFile(t, cfg)
+	for _, tc := range []struct {
+		name, add string
+		want      []string
+	}{
+		{"maxDepth on a flat reorder", "maxDepth: 2\n", []string{cfg, "maxDepth needs a tree reorder"}},
+		{"an explicit parentColumn that is not a column", "parentColumn: parent_id\n", []string{cfg, "parentColumn parent_id is not a column of the record"}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			err := activateCatalog(t, catalogFSPlugin{fsys: catalogOverlay(t, map[string]string{cfg: src + tc.add})})
+			if err == nil {
+				t.Fatal("boot accepted the reorder config")
+			}
+			for _, part := range tc.want {
+				if !strings.Contains(err.Error(), part) {
+					t.Fatalf("err = %v, want %q", err, part)
+				}
+			}
+		})
+	}
+
+	t.Run("the tree fixture stays a tree", func(t *testing.T) {
+		tree, err := cabana.CompiledListSchema([]party.Plugin{companionsFSPlugin{fsys: companionsOverlay(t, nil)}}, "acme.companions.links")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if tree.Reorder == nil || tree.Reorder.Flat {
+			t.Fatalf("links reorder = %+v", tree.Reorder)
+		}
+		raw, err := json.Marshal(tree)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if strings.Contains(string(raw), `"flat"`) {
+			t.Fatalf("tree list schema carries a flat key: %s", raw)
+		}
+	})
+}