SVV_lab1

import static org.junit.Assert.*;

import java.nio.BufferOverflowException;

import org.junit.Test;

public class StringConv {
     public int strToInt(String str) throws NumberFormatException, BufferOverflowException {
      double sum=0;

      boolean negative = false;
      if(str == null || str.isEmpty())
    	  throw new NumberFormatException();
      if(str.charAt(0) == '-')
    	  negative = true;
      int digit;
       for (int i = 0; i < str.length(); i++) {

    	if(Character.isLetter(str.charAt(i)))
    		throw new NumberFormatException();
        if(negative == true && i == str.length()-1)
        	continue;
        else
        	digit = (int)str.charAt(str.length()-i-1) - (int)'0';
         sum = sum + digit * (int)Math.pow(10, i);
       }

      if(negative == true)
    	sum = sum * (-1);

      if(Double.compare(sum, new Double(Integer.MAX_VALUE)) == 1)
    	  throw new BufferOverflowException();

       return (int)sum;
     }

     @Test(expected=NumberFormatException.class)
     public void testStringFormat()
     {
    	 strToInt("ab");
     }

     @Test
     public void testSingleDigit()
     {
    	 assertEquals("Single Digit Test", 5, strToInt("5"));
     }

     @Test
     public void testString()
     {
    	 assertEquals("String Test", 12, strToInt("12"));
     }

     @Test
     public void testNegative()
     {
    	 assertEquals("Negative Test", -20, strToInt("-20"));
     }


     @Test(expected=NumberFormatException.class)
     public void testNull()
     {
    	 strToInt(null);
     }

     @Test(expected=NumberFormatException.class)
     public void testEmpty()
     {
    	 strToInt("");
     }

     @Test(expected=BufferOverflowException.class)
     public void testBigNumber()
     {
    	 strToInt("1234567891");
     }
  }