// Teste de construção de um CNPJ e CPF Format sem view

cnpj_and_cpf_input_format.dart

class CNPJAndCPFInputFormat extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
    var value = _prepareValue(newValue);
    if (value.isNotEmpty && value.length <= 11) {
      value = _appendMask(value, '###.###.###-##');
    } else if (value.isNotEmpty && value.length <= 14) {
      value = _appendMask(value, '##.###.###/####-##');
    } else if (value.length > 14) {
      return oldValue;
    }

    return newValue.copyWith(
      text: value,
      selection: TextSelection.fromPosition(
        TextPosition(offset: value.length),
      ),
    );
  }
  String _prepareValue(TextEditingValue newValue) {
    var value = newValue.text;
    value = value.replaceAll(RegExp(r'[^\d]'), '');
    return value;
  }

  String _appendMask(String value, String mask) {
    for (var i = 0; i < value.length; i++) {
      mask = mask.replaceFirst('#', value[i]);
    }
    var lastHash = mask.indexOf('#');

    if (lastHash != -1) {
      mask = mask.characters.getRange(0, lastHash).join();
      if (RegExp(r'[^\d]').hasMatch(mask.characters.last)) {
        mask = mask.characters.getRange(0, mask.length - 1).join();
      }
    }

    return mask;
  }
}

cnpj_and_cpf_input_format_test.dart

import 'package:flutter_playground/src/cnpj_and_cpf_input_format.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  final formatter = CNPJAndCPFInputFormat();

  test('Should return empty when type letter', () {
    var newValue3 = const TextEditingValue(text: 'jac');
    newValue3 = formatter.formatEditUpdate(newValue3, newValue3);
    expect(newValue3.text, '');
  });

  group('CPF', () {
    test('Should format CPF when has 3 digit', () {
      var newValue3 = const TextEditingValue(text: '111');
      newValue3 = formatter.formatEditUpdate(newValue3, newValue3);
      expect(newValue3.text, '111');
    });
    test('Should format CPF when has 4 digit', () {
      const newValue4 = TextEditingValue(text: '1111');
      expect(formatter.formatEditUpdate(newValue4, newValue4).text, '111.1');
    });
    test('Should format CPF when has 6 digit', () {
      const newValue7 = TextEditingValue(text: '111111');
      expect(formatter.formatEditUpdate(newValue7, newValue7).text, '111.111');
    });
    test('Should format CPF when has 7 digit', () {
      const newValue7 = TextEditingValue(text: '1111111');
      expect(formatter.formatEditUpdate(newValue7, newValue7).text, '111.111.1');
    });
    test('Should format CPF when has 10 digit', () {
      const newValue10 = TextEditingValue(text: '111.111.1112');
      expect(formatter.formatEditUpdate(newValue10, newValue10).text, '111.111.111-2');
    });
    test('Should format CPF when has 11 digit', () {
      const newValue11 = TextEditingValue(text: '111.111.11122');
      expect(formatter.formatEditUpdate(newValue11, newValue11).text, '111.111.111-22');
    });
  });

  group('CNPJ', () {
    test('Should format CNPJ when has 12 digit', () {
      const newValue11 = TextEditingValue(text: '111.111.110-001');
      expect(formatter.formatEditUpdate(newValue11, newValue11).text, '11.111.111/0001');
    });
    test('Should format CNPJ when has 14 digit', () {
      const newValue11 = TextEditingValue(text: '11.111.111/000111');
      expect(formatter.formatEditUpdate(newValue11, newValue11).text, '11.111.111/0001-11');
    });
  });

  test('Should ignore if typed more less 14', () {
    const oldValue11 = TextEditingValue(text: '11.111.111/0001-11');
    const newValue11 = TextEditingValue(text: '11.111.111/0001-111');
    expect(formatter.formatEditUpdate(oldValue11, newValue11).text, '11.111.111/0001-11');
  });
}