feat: add the admin columns and the frontend permissions table

- users.permissions and users.last_seen as additive columns
- golem15_user_frontend_permissions (code, label, tab, comment)
- User gains LastSeen, read-only CreatedAt and UpdatedAt and the
  filterByGroup list scope; none of them is serialized
- migration tests roll back by position past the three new steps

updates/admin_columns_test.go

@@ -0,0 +1,109 @@
+package updates
+
+import (
+	"testing"
+
+	"git.golem15.com/golem15/summercms/modules/lagoon"
+	"github.com/go-gormigrate/gormigrate/v2"
+)
+
+// TestAdminColumnsMigrations applies the three admin migrations on a real
+// Postgres, checks what each one adds, rolls each one back on its own and
+// applies them again.
+func TestAdminColumnsMigrations(t *testing.T) {
+	sqlDB := dedicatedDB(t, "user_admin_columns")
+	gdb, err := lagoon.Use(t.Context(), sqlDB)
+	if err != nil {
+		t.Fatal(err)
+	}
+	m := gormigrate.New(gdb, &gormigrate.Options{
+		TableName:      "summer_migrations_golem15_user",
+		UseTransaction: true,
+	}, All())
+	if err := m.Migrate(); err != nil {
+		t.Fatal(err)
+	}
+
+	columnType := func(table, column string) (string, string) {
+		t.Helper()
+		var row struct {
+			DataType   string
+			IsNullable string
+		}
+		if err := gdb.Raw(`SELECT data_type, is_nullable FROM information_schema.columns WHERE table_name = ? AND column_name = ?`, table, column).Scan(&row).Error; err != nil {
+			t.Fatal(err)
+		}
+		return row.DataType, row.IsNullable
+	}
+	if typ, null := columnType("users", "permissions"); typ != "text" || null != "YES" {
+		t.Fatalf("users.permissions = %q nullable %q", typ, null)
+	}
+	if typ, null := columnType("users", "last_seen"); typ != "timestamp with time zone" || null != "YES" {
+		t.Fatalf("users.last_seen = %q nullable %q", typ, null)
+	}
+	const table = "golem15_user_frontend_permissions"
+	want := map[string][2]string{
+		"id":         {"integer", "NO"},
+		"code":       {"character varying", "NO"},
+		"label":      {"character varying", "NO"},
+		"tab":        {"character varying", "NO"},
+		"comment":    {"character varying", "YES"},
+		"created_at": {"timestamp with time zone", "YES"},
+		"updated_at": {"timestamp with time zone", "YES"},
+	}
+	for column, shape := range want {
+		if typ, null := columnType(table, column); typ != shape[0] || null != shape[1] {
+			t.Fatalf("%s.%s = %q nullable %q", table, column, typ, null)
+		}
+	}
+	insert := `INSERT INTO golem15_user_frontend_permissions (code, label, tab) VALUES (?, ?, ?)`
+	if err := gdb.Exec(insert, "blog.post", "Post", "Blog").Error; err != nil {
+		t.Fatal(err)
+	}
+	if err := gdb.Exec(insert, "blog.post", "Post again", "Blog").Error; err == nil {
+		t.Fatal("a duplicate permission code was accepted")
+	}
+	// An existing user keeps working with both columns empty.
+	if err := gdb.Exec(`INSERT INTO users (email) VALUES ('columns@example.test')`).Error; err != nil {
+		t.Fatal(err)
+	}
+	var empty int64
+	if err := gdb.Raw(`SELECT COUNT(*) FROM users WHERE permissions IS NULL AND last_seen IS NULL`).Scan(&empty).Error; err != nil || empty != 1 {
+		t.Fatalf("users with empty admin columns = %d err = %v", empty, err)
+	}
+
+	if err := m.RollbackMigration(frontendPermissionsMigrations[0]); err != nil {
+		t.Fatal(err)
+	}
+	if gdb.Migrator().HasTable(table) {
+		t.Fatalf("%s survived rollback", table)
+	}
+	if err := m.RollbackMigration(usersLastSeenMigrations[0]); err != nil {
+		t.Fatal(err)
+	}
+	if gdb.Migrator().HasColumn("users", "last_seen") || !gdb.Migrator().HasColumn("users", "permissions") {
+		t.Fatal("last_seen rollback touched the wrong column")
+	}
+	if err := m.RollbackMigration(usersPermissionsMigrations[0]); err != nil {
+		t.Fatal(err)
+	}
+	if gdb.Migrator().HasColumn("users", "permissions") {
+		t.Fatal("users.permissions survived rollback")
+	}
+	for _, kept := range []string{"users", "user_groups", "user_throttle", "user_api_tokens"} {
+		if !gdb.Migrator().HasTable(kept) {
+			t.Fatalf("rollback dropped %s", kept)
+		}
+	}
+	var users int64
+	if err := gdb.Raw(`SELECT COUNT(*) FROM users`).Scan(&users).Error; err != nil || users != 1 {
+		t.Fatalf("users after rollback = %d err = %v", users, err)
+	}
+
+	if err := m.Migrate(); err != nil {
+		t.Fatalf("re-up: %v", err)
+	}
+	if !gdb.Migrator().HasTable(table) || !gdb.Migrator().HasColumn("users", "permissions") || !gdb.Migrator().HasColumn("users", "last_seen") {
+		t.Fatal("re-up did not restore the admin columns")
+	}
+}