Function GetQueryResult

testing/generation/command_docs/create_tests.go:212–255

GetQueryResult runs the query against a Postgres server to validate that the query is syntactically valid. It then tests the query against the Postgres parser and Postgres-Vitess AST converter to check the current level of support. It returns a string that may be inserted directly into a test source

(query string)

// tests the query against the Postgres parser and Postgres-Vitess AST converter to check the current level of support.
// It returns a string that may be inserted directly into a test source file (two tabs are prefixed).
func GetQueryResult(query string) (string, error) {
	var err error
	ctx := context.Background()
	if postgresVerificationConnection == nil {
		connectionString := fmt.Sprintf("postgres://postgres:password@127.0.0.1:%d/", 5432)
		postgresVerificationConnection, err = pgx.Connect(ctx, connectionString)
		if err != nil {
			return "", err
		}
	}
	testQuery := fmt.Sprintf("DO $SYNTAX_CHECK$ BEGIN RETURN; %s; END; $SYNTAX_CHECK$;", query)
	_, err = postgresVerificationConnection.Exec(ctx, testQuery)
	if err != nil && strings.Contains(err.Error(), "syntax error") {
		// We only care about syntax errors, as statements may rely on internal state, which is not what we're testing
		// There are statements that will not execute inside our DO block due to how Postgres handles some queries, so
		// to confirm that they're syntax errors, we'll run them outside the block. All such queries should be
		// non-destructive, so this should be safe. All other queries will still return a syntax error.
		_, err = postgresVerificationConnection.Exec(ctx, query)
		// Run a ROLLBACK as some commands may put the connection (not the database) in a bad state
		_, _ = postgresVerificationConnection.Exec(ctx, "ROLLBACK;")
		if err != nil && strings.Contains(err.Error(), "syntax error") {
			return "", fmt.Errorf("%s\n%s", err, query)
		}
	}
	formattedQuery := strings.ReplaceAll(query, `"`, `\"`)
	statements, err := parser.Parse(query)
	if err != nil || len(statements) == 0 {
		return fmt.Sprintf("\t\tUnimplemented(\"%s\"),\n", formattedQuery), nil
	}
	for _, statement := range statements {
		vitessAST, err := func() (vitessAST sqlparser.Statement, err error) {
			defer func() {
				if recoverVal := recover(); recoverVal != nil {
					vitessAST = nil
				}
			}()
			return ast.Convert(statement)
		}()
		if err != nil || vitessAST == nil {
			return fmt.Sprintf("\t\tParses(\"%s\"),\n", formattedQuery), nil
		}
	}
	return fmt.Sprintf("\t\tConverts(\"%s\"),\n", formattedQuery), nil
}