function extractMatrixColumn(matrix, column) {
  if (matrix.length === 0 || matrix[0].length === 0) {
    throw 'input matrix is empty'
  } else if (matrix[0].length < column) {
    throw 'column is outside of matrix bounds'
  }
    
  const col = [];

  for (row of matrix) {
    col.push(row[column]);
  }

  return col;
}



/**
* Test Suite 
*/
describe('extractMatrixColumn()', () => {
    it('returns largest positive integer possible for digit count', () => {
        // arrange
        const matrix = [[1, 1, 1, 2], [0, 5, 0, 4], [2, 1, 3, 6]];
        const column = 2;
        
        // act
        const result = extractMatrixColumn(matrix, column);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toEqual([1, 0, 3]);
    });
    
    it('throws an error if matrix is empty', () => {
       const matrix = [];
       const column = 2;
       
       const error = 'input matrix is empty';
       
       expect(() => extractMatrixColumn(matrix, column)).toThrow(error);
    });
    
    it('throws an error if matrix row is empty', () => {
       const matrix = [[]];
       const column = 2;
       
       const error = 'input matrix is empty';
       
       expect(() => extractMatrixColumn(matrix, column)).toThrow(error);
    });
    
    it('throws an error if column is invalid', () => {
       const matrix = [[1],[2]];
       const column = 2;
       
       const error = 'column is outside of matrix bounds';
       
       expect(() => extractMatrixColumn(matrix, column)).toThrow(error);
    });
});