function differentSymbolsNaive(str) {
    if (typeof str !== 'string') {
        throw 'input is expected to be a string';
    } else if (str.length === 0) {
        return 0;
    } else if (str.length === 1) {
        return 1;
    }
    
    const uniqueChars = new Set;
    
    for (char of str) {
        uniqueChars.add(char)
    }
    
    return uniqueChars.size;
}



/**
* Test Suite 
*/
describe('differentSymbolsNaive()', () => {
    it('returns count of unique characters', () => {
        // arrange
        const str = 'cabca';
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(3);
    });
    
   it('returns count of unique chars for mix of numbers, letters, and symbols', () => {
      const str = 'ief8923(*&#ief';
      
      const result = differentSymbolsNaive(str);
      
      expect(result).toEqual(11); 
   });
   
   it ('returns 0 for an empty string', () => {
       const str = '';
       
       const result = differentSymbolsNaive(str);
       
       expect(result).toBe(0);
   });
   
   it ('returns 1 for string with single char', () => {
       const str = '3';
       
       const result = differentSymbolsNaive(str);
       
       expect(result).toBe(1);
   });
   
   it ('throws an error if not passed a string', () => {
       const str = 234;
       
       const error = 'input is expected to be a string';
       
       expect(() => differentSymbolsNaive(str)).toThrow(error);
   });
});