Author: Víctor Coelho

These solutions require Python and Pytest to be installed.

Exercise solutions can be run from the main.py in conjunction with the input.txt that contains an assortment of CNPJ strings. From the root of the repository, use the command:
python main.py < input.txt

To see the ouput in your terminal.

Both Solutions also come with Pytest tests. To run these tests, from the root of the repository, use the command in your terminal:
pytest -v

Pytest will then display the results of all tests created for the solutions of exercises. Below all test functions are described.

This link leads to a video explanation of both Exercise Solutions and, also, an example of running Pytest and the main.py function.

To skip the Solution Explanation and watch only the Execution, you can access via this or skip to 9:05 in the video.

File: ex1_test.py

test_invalid_punct(): Test for invalid characters where it should be a punctiation character. test_invalid_size(): Test for invalid CNPJ string size. test_invalid_characters(): Tests for invalid characters - there should be only numbers or the correct punctuation characters. test_valid_formatted_string(): Tests for valid input of a formatted CNPJ string test_valid_numbers_only_string(): Tests for valid input of a numbers only CNPJ string
test_valid_numbers_only_string(): Tests for valid input of a numbers only CNPJ string

File: ex2_test.py

test_correct_format(): Checks if format_cnpj() outputs the correct integer list from a cnpj string
test_invalid_string_size(): Checks if format_cnpj() outputs an empty list when it encounters invalid cnpj string sizes.
test_correct_validate_cnpj(): Checks if validate_cnpj() outputs the correct message when it receives a valid CNPJ string. test_invalid_validate_cnpj(): Checks if validate_cnpj() correctly outputs an invalid message when the input CNPJ is invalid.

File name: ex1_function.py
Function name: check_cnpj_string()cnpj - receives a cnpj string as input, returns if the CNPJ format is valid or invalid.

Exercise 1 solution involved creating an algorithm to run through each CNPJ string passed as parameter, checking for possible inconsistencies when compared to two possible expected formats:

Formatted CNPJ string: "xx.xxx.xxx/xxxx-xx"
Number only CNPJ string: "xxxxxxxxxxxxxx"
Where x must be a valid number between 0-9.

These are the conditions and the algorithm checks for:

There are only two accepted string sizes - 18 characters for formatted CNPJ strings and 14 characters for numbers only CNPJ strings.

For formatted CNPJ strings, checks if all correct punctuation characters are on their correct positions.

For formatted CNPJ strings, checks if all digits are numbers

Checks if a number only CNPJ string contains only numbers.

If the string passes all inconsistency tests, it is correctly formatted.

File name: ex2_function.py
Functions: format_cnpj(cnpj) - receives a cnpj string as input. Outputs a list of integers based on input string.
generate_validation_digit(cnpj, digit_number) - receives a cnpj integer list and a digit_number informing what validation digit should be generated. Outputs integer with generated validation number.
validate_cnpj(cnpj) - receives a cnpj string as input. Outputs a message informing if it is a valid cnpj string based on its validation digits.

Exercise 2 solution involved utilizing an algorithm to generate validation digits for a given CNPJ string and compare the generated digits with the actual validation digits from the input CNPJ string.

The validate_cnpj function invokes generate_validation_digit to generate the two validation digits that are the last two digits from a CNPJ. Compares the generated validation digits with the actual input validation digits. If they are the same, outputs a message that the CNPJ is valid. Otherwise, outputs a message that the CNPJ is invalid.

The algorithm used to generate the validation digits is obtained from a Modulo-11 operation.