ast/ast_test.go

package ast

import (
	"matheval/token"
	"testing"
)

// Compile-time check: both types satisfy Node.
var (
	_ Node = (*NumberLit)(nil)
	_ Node = (*BinaryExpr)(nil)
)

func TestNumberLit(t *testing.T) {
	n := &NumberLit{Value: 3.14}
	if n.Value != 3.14 {
		t.Fatalf("expected 3.14, got %f", n.Value)
	}
}

func TestBinaryExpr(t *testing.T) {
	left := &NumberLit{Value: 1}
	right := &NumberLit{Value: 2}
	expr := &BinaryExpr{
		Op:    token.Plus,
		Left:  left,
		Right: right,
	}

	if expr.Op != token.Plus {
		t.Fatalf("expected Plus, got %v", expr.Op)
	}
	if expr.Left != left {
		t.Fatal("Left child mismatch")
	}
	if expr.Right != right {
		t.Fatal("Right child mismatch")
	}
}

func TestNestedBinaryExpr(t *testing.T) {
	// Represents: (1 + 2) * 3
	tree := &BinaryExpr{
		Op: token.Star,
		Left: &BinaryExpr{
			Op:    token.Plus,
			Left:  &NumberLit{Value: 1},
			Right: &NumberLit{Value: 2},
		},
		Right: &NumberLit{Value: 3},
	}

	if tree.Op != token.Star {
		t.Fatalf("expected Star, got %v", tree.Op)
	}

	inner, ok := tree.Left.(*BinaryExpr)
	if !ok {
		t.Fatal("Left should be *BinaryExpr")
	}
	if inner.Op != token.Plus {
		t.Fatalf("expected Plus, got %v", inner.Op)
	}
}