golox/interpreter/interpreter_test.go

// FILE: interpreter_test.go
package interpreter_test

import (
	"golox/ast"
	"golox/interpreter"
	"golox/token"
	"testing"
)

func TestInterpretLiteralExpr(t *testing.T) {
	i := interpreter.New()
	literal := &ast.LiteralExpr{Value: 42}

	result := i.VisitLiteralExpr(literal)
	if result != 42 {
		t.Errorf("expected 42, got %v", result)
	}
}

func TestInterpretGroupingExpr(t *testing.T) {
	i := interpreter.New()
	literal := &ast.LiteralExpr{Value: 42}
	grouping := &ast.GroupingExpr{Expression: literal}

	result := i.VisitGroupingExpr(grouping)
	if result != 42 {
		t.Errorf("expected 42, got %v", result)
	}
}

func TestInterpretUnaryExpr(t *testing.T) {
	i := interpreter.New()
	literal := &ast.LiteralExpr{Value: 42.0}
	unary := &ast.UnaryExpr{
		Operator: token.Token{Type: token.MINUS, Lexeme: "-"},
		Right:    literal,
	}

	result := i.VisitUnaryExpr(unary)
	if result != -42.0 {
		t.Errorf("expected -42, got %v", result)
	}
}

func TestInterpretUnaryExprBang(t *testing.T) {
	i := interpreter.New()
	literal := &ast.LiteralExpr{Value: true}
	unary := &ast.UnaryExpr{
		Operator: token.Token{Type: token.BANG, Lexeme: "!"},
		Right:    literal,
	}

	result := i.VisitUnaryExpr(unary)
	if result != false {
		t.Errorf("expected false, got %v", result)
	}
}

func TestInterpretErrorExpr(t *testing.T) {
	i := interpreter.New()
	errorExpr := &ast.ErrorExpr{Value: "error"}

	defer func() {
		if r := recover(); r != "error" {
			t.Errorf("expected panic with 'error', got %v", r)
		}
	}()

	i.VisitErrorExpr(errorExpr)
}

func TestInterpretExpr(t *testing.T) {
	i := interpreter.New()
	literal := &ast.LiteralExpr{Value: 42.0}

	defer func() {
		if r := recover(); r != nil {
			t.Errorf("unexpected panic: %v", r)
		}
	}()

	result := i.InterpretExpr(literal)
	if result != "42" {
		t.Errorf("expected '42', got %v", result)
	}
}

func TestInterpretBinaryExpr(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 2.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.STAR, Lexeme: "*"},
		Right:    right,
	}

	result := i.VisitBinaryExpr(binary)
	if result != 84.0 {
		t.Errorf("expected 84, got %v", result)
	}
}

func TestInterpretBinaryExprDivisionByZero(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 0.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.SLASH, Lexeme: "/"},
		Right:    right,
	}

	defer func() {
		if r := recover(); r != "Division by zero [line 0]" {
			t.Errorf("expected panic with 'division by zero', got %v", r)
		}
	}()

	i.VisitBinaryExpr(binary)
}

func TestInterpretBinaryExprAddition(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 2.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.PLUS, Lexeme: "+"},
		Right:    right,
	}

	result := i.VisitBinaryExpr(binary)
	if result != 44.0 {
		t.Errorf("expected 44, got %v", result)
	}
}

func TestInterpretBinaryExprSubtraction(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 2.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.MINUS, Lexeme: "-"},
		Right:    right,
	}

	result := i.VisitBinaryExpr(binary)
	if result != 40.0 {
		t.Errorf("expected 40, got %v", result)
	}
}

func TestInterpretBinaryExprStringConcatenation(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: "foo"}
	right := &ast.LiteralExpr{Value: "bar"}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.PLUS, Lexeme: "+"},
		Right:    right,
	}

	result := i.VisitBinaryExpr(binary)
	if result != "foobar" {
		t.Errorf("expected 'foobar', got %v", result)
	}
}

func TestInterpretBinaryExprInvalidOperands(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: "foo"}
	right := &ast.LiteralExpr{Value: 42.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.PLUS, Lexeme: "+"},
		Right:    right,
	}

	defer func() {
		if r := recover(); r != "Operands must be two numbers or two strings [line 0]" {
			t.Errorf("expected panic with 'operands must be two numbers or two strings', got %v", r)
		}
	}()

	i.VisitBinaryExpr(binary)
}

func TestInterpretBinaryExprComparison(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 2.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.GREATER, Lexeme: ">"},
		Right:    right,
	}

	result := i.VisitBinaryExpr(binary)
	if result != true {
		t.Errorf("expected true, got %v", result)
	}
}

func TestInterpretBinaryExprComparisonEqual(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 42.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.EQUAL_EQUAL, Lexeme: "=="},
		Right:    right,
	}

	result := i.VisitBinaryExpr(binary)
	if result != true {
		t.Errorf("expected true, got %v", result)
	}
}

func TestInterpretBinaryExprComparisonNotEqual(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 2.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.BANG_EQUAL, Lexeme: "!="},
		Right:    right,
	}

	result := i.VisitBinaryExpr(binary)
	if result != true {
		t.Errorf("expected true, got %v", result)
	}
}

func TestInterpretBinaryExprComparisonInvalidOperands(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: "foo"}
	right := &ast.LiteralExpr{Value: 42.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.GREATER, Lexeme: ">"},
		Right:    right,
	}

	defer func() {
		if r := recover(); r != "Operands of operator '>' must be numbers [line 0]" {
			t.Errorf("expected panic with 'operands must be numbers', got %v", r)
		}
	}()

	i.VisitBinaryExpr(binary)
}

func TestInterpretBinaryExprInvalidOperatorType(t *testing.T) {
	i := interpreter.New()
	left := &ast.LiteralExpr{Value: 42.0}
	right := &ast.LiteralExpr{Value: 2.0}
	binary := &ast.BinaryExpr{
		Left:     left,
		Operator: token.Token{Type: token.EOF, Lexeme: ""},
		Right:    right,
	}

	defer func() {
		if r := recover(); r != "Unknown binary operator '' [line 0]" {
			t.Errorf("expected panic with 'unknown operator type', got %v", r)
		}
	}()

	i.VisitBinaryExpr(binary)
}