import 'package:test/test.dart';

//Binary number to octal number conversion

void main() {

test("binary_to_octal -1111", () {

expect(binaryToOctal("-1111"), equals("-17"));

});

test("binary_to_octal 101011", () {

expect(binaryToOctal("101011"), equals("53"));

});

test("binary_to_octal rasies error when number is invalid", () {

expect(() => binaryToOctal("-1011a01"), throwsFormatException);

});

test("binary_to_octal of empty string raises error", () {

expect(() => binaryToOctal(""), throwsFormatException);

});

}

String binaryToOctal(String binaryString) {

binaryString = binaryString.trim();

if (binaryString.isEmpty) {

throw new FormatException("An empty value was passed to the function");

}

bool isNegative = binaryString[0] == "-";

if (isNegative) binaryString = binaryString.substring(1);

String octalValue = "";

int binary;

try {

binary = int.parse(binaryString);

} catch (e) {

throw new FormatException("An invalid value was passed to the function");

}

int currentBit;

int j = 1;

while (binary > 0) {

int code3 = 0;

for (int i = 0; i < 3; i++) {

currentBit = binary % 10;

binary = binary ~/ 10;

code3 += currentBit * j;

j *= 2;

}

octalValue = code3.toString() + octalValue;

j = 1;

}

if (isNegative) {

return "-" + octalValue;

}

return octalValue;

}