test: add test case for exponentiation-expr

Author: link-duan

lexer.go

@@ -87,6 +87,9 @@ func (l *lexer) next() (*Token, error) {
 	case '&':
 		l.nextch()
 		return newToken(l.pos, l.pos, Concat, "&"), nil
+	case '^':
+		l.nextch()
+		return newToken(l.pos, l.pos, Exponentiation, "^"), nil
 	case '%':
 		l.nextch()
 		return newToken(l.pos, l.pos, Percent, "%"), nil

parser_test.go

@@ -7,6 +7,7 @@ func TestParse(t *testing.T) {
 		src      string
 		expected string
 	}{
+		{"=A1^B1", "BinaryExpr(Left: CellExpr(A1), Operator: ^, Right: CellExpr(B1))"},
 		{"=A1&B1", "BinaryExpr(Left: CellExpr(A1), Operator: &, Right: CellExpr(B1))"},
 		{"=1<>2", "BinaryExpr(Left: LiteralExpr(Value: 1), Operator: <>, Right: LiteralExpr(Value: 2))"},
 		{"=$A:$A", "RangeExpr(CellExpr($A):CellExpr($A))"},