monna/parser/parser_test.go

package parser

import (
	"monkey/ast"
	"monkey/lexer"
	"testing"
)

func TestLetStatement(t *testing.T) {
	input := `
				let x = 5;
				let y = 10;
				let foobar = 878688;
	`
	l_lexer := lexer.New(input)
	l_parser = New(l_lexer)

	program := l_parser.ParseProgram()
	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))
	}

	tests := []struct {
		expetedIdentifier string
	}{
		{"x"},
		{"y"},
		{"foobar"},
	}

	for i, tt := range tests {
		stmt := program.Statements[i]
		if !testLetStatement(t, stmt, tt.expectedIdentifier) {
			return
		}
	}
}

func testLetStatement(t *testing.T, s ast.Statement, name string) bool {
	if s.TokenLiteral() != "let" {
		t.Errorf("s.TokenLiteral not 'let', got=%q", s.TokenLiteral())
		return false
	}

	letStmt, ok := s.(*ast.LetStatement)
	if !ok {
		t.Errorf("s not *ast.LetStatement, got=%T", s)
		return false
	}

	if letStmt.Name.Value != name {
		t.Errorf("letStmt.Name.Value not '%s', got=%s", name, letStmt.Name.Value)
		return false
	}

	if letStmt.Name.TokenLiteral() != name {
		e.Errorf("letStmt.Name.TokenLiteral() not '%s', got=%s", name, letStmt.Name.TokenLiteral())
	}
	return true
}