function differentSymbolsNaive(str) {
    // get number of unique "characters"
    return (str === null || str === undefined) ? 0 : Array.from(new Set(str.toString().split(""))).length;
}



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

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(3);
    });
    
    it('returns count of unique characters', () => {
        // arrange
        const str = 'c1a21bca'; // string with numbers
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(5);
    });
    
    it('returns count of unique characters', () => {
        // arrange
        const str = 1233; // number
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(3);
    });
    
    it('returns count of unique characters', () => {
        // arrange
        const str = '+'; // 1 character (symbol)
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(1);
    });
    
    it('returns count of unique characters', () => {
        // arrange
        const str = ''; // empty string
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(0);
    });
    
    it('returns count of unique characters', () => {
        // arrange
        const str = null; // null
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(0);
    });
    
    it('returns count of unique characters', () => {
        // arrange
        const str = undefined; // undefined
        
        // act
        const result = differentSymbolsNaive(str);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toBe(0);
    });
});