waiig15/parser/parser_return_test.go

package parser

import (
	"testing"

	"code.osinet.fr/fgm/waiig15/ast"
	"code.osinet.fr/fgm/waiig15/lexer"
)

func TestReturnStatements(t *testing.T) {
	// Try removing the ident, the =, or both, to get human-readable errors.
	input := `
return 5;
return 10;
return 993322;
`
	l := lexer.New(input)
	p := New(l)

	program := p.ParseProgram()
	checkParserErrors(t, p)
	if program == nil {
		t.Fatalf("ParseProgram() returned nil.")
	}

	if len(program.Statements) != 3 {
		t.Fatalf("program.Statements does not contain 3 statements, got=%d",
			len(program.Statements))
	}

	for _, stmt := range program.Statements {
		// Statement is an interface, we need a concrete type for the value, and
		// our test input only contains Let statements.
		returnStmt, ok := stmt.(*ast.ReturnStatement)
		if !ok {
			t.Errorf("s not *ast.ReturnStatement{}, got=%T", stmt)
			continue
		}
		if returnStmt.TokenLiteral() != "return" {
			t.Errorf("s.TokenLiteral not 'return', got=%q",
				stmt.TokenLiteral())
		}
	}
}