Add Renavam digit calculator (#19)

README.md

@@ -131,6 +131,19 @@ println(doc.String()) // prints 247003181023
 println(doc.Format()) // prints 247003181023
 ```
 
+### Renavam (Registro Nacional de Veículos Automotores)
+
+National Registry of Motor Vehicles
+
+```go
+doc, err := brdocs.NewRenavam("61855253306")
+if err != nil {
+    panic(err)
+}
+println(doc.String()) // prints 61855253306
+println(doc.Format()) // prints 6185.525330-6
+```
+
 ## License
 
 This project is released under the MIT licence. See [LICENSE](https://github.com/brazanation/go-documents/blob/master/LICENSE) for more details.

renavam.go

@@ -0,0 +1,40 @@
+package brdocs
+
+import (
+	"fmt"
+	"github.com/brazanation/go-documents/internal"
+	"github.com/brazanation/go-documents/internal/calculator"
+)
+
+const RenavamType internal.DocumentType = "Renavam"
+
+const (
+	renavamLength         int    = 11
+	renavamNumberOfDigits int    = 1
+	renavamValidatorRegex string = `^([\d]{4})([\d]{6})([\d]{1})$`
+	renavamFormatterRegex string = "$1.$2-$3"
+)
+
+type renavam struct {}
+
+// NewRenavam is the constructor of renavam
+func NewRenavam(number string) (internal.Document, error) {
+	d, err := internal.NewDocument(
+		RenavamType,
+		number,
+		renavamLength,
+		renavamNumberOfDigits,
+		renavamFormatterRegex,
+		renavamValidatorRegex,
+		renavam{},
+	)
+	return d, err
+}
+
+func (r renavam) CalculateDigit(base string) string {
+	m := calculator.NewModule11(base)
+	m.WithMultipliers(2, 3, 4, 5, 6, 7, 8, 9, 2, 3)
+	m.ReplaceWhen(0, 10)
+	m.MultiplySumBy(10)
+	return fmt.Sprintf("%d", m.Calculate())
+}

renavam_test.go

@@ -0,0 +1,37 @@
+package brdocs_test
+
+import (
+	"github.com/brazanation/go-documents"
+	"github.com/brazanation/go-documents/internal/test"
+
+	"testing"
+)
+
+func TestRenavamShouldBeValid(t *testing.T) {
+	renavam, err := brdocs.NewRenavam("61855253306")
+	internal_test.AssertValidDocument(t, renavam, err)
+}
+
+func TestRenavamShouldBeFormatted(t *testing.T) {
+	renavam, err := brdocs.NewRenavam("73197444810")
+	internal_test.AssertValidDocument(t, renavam, err)
+	internal_test.AssertDocumentFormatted(t, renavam, "7319.744481-0")
+}
+
+func TestRenavamShouldReturnErrorForRepeatedNumber(t *testing.T) {
+	number := "11111111111"
+	_, err := brdocs.NewRenavam(number)
+	internal_test.AssertNotValidDocument(t, number, err, "Renavam(11111111111) is invalid")
+}
+
+func TestRenavamShouldReturnErrorForInvalidNumber(t *testing.T) {
+	number := "61855253307"
+	_, err := brdocs.NewRenavam(number)
+	internal_test.AssertNotValidDocument(t, number, err, "Renavam(61855253307) is invalid")
+}
+
+func TestRenavamShouldReturnErrorForEmptyNumber(t *testing.T) {
+	number := ``
+	_, err := brdocs.NewRenavam(number)
+	internal_test.AssertNotValidDocument(t, number, err, "Renavam must not be empty")
+}