Allow adding an index to a table created in the same migration (#451)

Allow the `create_index` operation to add an index to a table that was
created by an operation earlier in the same migration.

The following migration would previously have failed to start:

```json
{
  "name": "43_multiple_ops",
  "operations": [
    {
      "create_table": {
        "name": "players",
        "columns": [
          {
            "name": "id",
            "type": "serial",
            "pk": true
          },
          {
            "name": "name",
            "type": "varchar(255)",
            "check": {
              "name": "name_length_check",
              "constraint": "length(name) > 2"
            }
          }
        ]
      }
    },
    {
      "create_index": {
        "name": "idx_player_name",
        "table": "players",
        "columns": [
          "name"
        ]
      }
    }
  ]
}
```

As of this PR the migration can be started.

The above migration does not validate yet, but it can be started
successfully with the --skip-validation flag to the start command.

Part of #239

pkg/migrations/op_create_index.go

@@ -16,14 +16,16 @@ import (
 var _ Operation = (*OpCreateIndex)(nil)
 
 func (o *OpCreateIndex) Start(ctx context.Context, conn db.DB, latestSchema string, tr SQLTransformer, s *schema.Schema, cbs ...CallbackFn) (*schema.Table, error) {
+	table := s.GetTable(o.Table)
+
 	// create index concurrently
 	stmtFmt := "CREATE INDEX CONCURRENTLY %s ON %s"
 	if o.Unique != nil && *o.Unique {
 		stmtFmt = "CREATE UNIQUE INDEX CONCURRENTLY %s ON %s"
 	}
 	stmt := fmt.Sprintf(stmtFmt,
 		pq.QuoteIdentifier(o.Name),
-		pq.QuoteIdentifier(o.Table))
+		pq.QuoteIdentifier(table.Name))
 
 	if o.Method != nil {
 		stmt += fmt.Sprintf(" USING %s", string(*o.Method))

pkg/migrations/op_create_index_test.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 
 	"github.com/xataio/pgroll/pkg/migrations"
+	"github.com/xataio/pgroll/pkg/roll"
 )
 
 func TestCreateIndex(t *testing.T) {
@@ -313,3 +314,52 @@ func TestCreateIndexOnMultipleColumns(t *testing.T) {
 		},
 	}})
 }
+
+func TestCreateIndexOnTableCreatedInSameMigration(t *testing.T) {
+	t.Parallel()
+
+	ExecuteTests(t, TestCases{
+		{
+			name: "create index on newly created table",
+			migrations: []migrations.Migration{
+				{
+					Name: "01_add_table",
+					Operations: migrations.Operations{
+						&migrations.OpCreateTable{
+							Name: "users",
+							Columns: []migrations.Column{
+								{
+									Name: "id",
+									Type: "serial",
+									Pk:   ptr(true),
+								},
+								{
+									Name:     "name",
+									Type:     "varchar(255)",
+									Nullable: ptr(false),
+								},
+							},
+						},
+						&migrations.OpCreateIndex{
+							Name:    "idx_users_name",
+							Table:   "users",
+							Columns: []string{"name"},
+						},
+					},
+				},
+			},
+			afterStart: func(t *testing.T, db *sql.DB, schema string) {
+				// The index has been created on the underlying table.
+				IndexMustExist(t, db, schema, migrations.TemporaryName("users"), "idx_users_name")
+			},
+			afterRollback: func(t *testing.T, db *sql.DB, schema string) {
+				// The index has been dropped from the the underlying table.
+				IndexMustNotExist(t, db, schema, "users", "idx_users_name")
+			},
+			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
+				// The index remains on the underlying table.
+				IndexMustExist(t, db, schema, "users", "idx_users_name")
+			},
+		},
+	}, roll.WithSkipValidation(true)) // TODO: Remove once this migration passes validation
+}