DeletePanendromeTest

// Question at:
//  https://www.facebook.com/groups/Javagroup123/permalink/10156296803156664/

import junit.framework.TestCase;

public class DeletePanendromeTest extends TestCase {

    public boolean validPalindrome(String s) {
        int len = s.length();
        int left = 0,right = len-1;

        while(left < right){
            if(s.charAt(left) == s.charAt(right)){
                left++;
                right--;
            }else{
                return isPalindrome(s.substring(0,left) + s.substring(left+1,len)) ||
                        isPalindrome(s.substring(0,right) + s.substring(right+1,len));
            }
        }


        return true;
    }

    private boolean isPalindrome(String s){
        int left = 0,right = s.length()-1;
        while(left < right){
            if(s.charAt(left++) != s.charAt(right--)) return false;
        }
        return true;
    }

    public void testEmpty() {
        assertPalendromeResultEquals("Delete no characters; is still a palendrome;", true, "");
    }

    public void testOneChar() {
        assertPalendromeResultEquals("Do nothing or delete one to get empty string;", true, "x");
    }

    public void test_xy() {
        assertPalendromeResultEquals("Delete either char;", true, "xy");
    }

    public void test_xx() {
        assertPalendromeResultEquals("Do nothing or delete either char;", true, "xx");
    }

    public void test_xyz() {
        assertPalendromeResultEquals("Can't be made a palendrome;", false, "xyz");
    }

    public void test_xyx() {
        assertPalendromeResultEquals("Do nothing or delete middle char;", true, "xyx");
    }

    public void test_xyy() {
        assertPalendromeResultEquals("Delete 1st char;", true, "xyy");
    }

    public void test_xxy() {
        assertPalendromeResultEquals("Delete last char;", true, "xxy");
    }

    public void test_abba() {
        assertPalendromeResultEquals("Do nothing or delete either 'b';", true, "abba");
    }

    public void test_abcba() {
        assertPalendromeResultEquals("Do nothing or delete the center 'c';", true, "abcba");
    }

    public void test_abccba() {
        assertPalendromeResultEquals("Do nothing or delete either center 'c';", true, "abccba");
    }

    public void test_abaaaaafa() {
        assertPalendromeResultEquals("Can't delete both 'b' and 'f';", false, "abaaaaafa");
    }

    public void test_ababababab() {
        assertPalendromeResultEquals("Delete first or last char;", true, "ababababab");
    }

    public void test_abababxbabab() {
        assertPalendromeResultEquals("Must delete first char;", true, "abababxbabab");
    }

    public void test_ababaxababab() {
        assertPalendromeResultEquals("Must delete last char;", true, "ababaxababab");
    }

    public void test_abcdedcbfa() {
        assertPalendromeResultEquals("Delete the 'f';", true, "abcdedcbfa");
    }

    void assertPalendromeResultEquals(final String message, final boolean expected, final String inputString) {

        if (isPalindrome(inputString)) {
            final String doNothingPrefix = "Do nothing or ";
            assertTrue("Expecting the message <" + message + "> to start with the text <" + doNothingPrefix + ">;",
                    message.startsWith(doNothingPrefix) || inputString.length() == 0);
        }

        assertEquals(message, expected, validPalindrome(inputString));
    }

}