function alphabetSubsequence(str) {
    //  write code here.
    //Assume all input should have at least two characters and 
    //be lower case without any non-alphabetic characters
    if (typeof str !== 'string') return false
    if (str.length < 2) return false
    str = str.replace(/[^A-Za-z]/g, '').toLowerCase();
    
    for(let i = 0; i < str.length - 1; i++) {
        if ((str[i] >= str[i + 1])) return false
    }
    return true
}



/**
* Test Suite 
// */
describe('alphabetSubsequence()', () => {
    it('returns false when it has duplicate letters', () => {
        // arrange
        const str = 'effg';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 1: ", result);
        
        // assert
        expect(result).toBe(false);
    });

    it('returns false when NOT in ascending a - z order', () => {
        // arrange
        const str = 'cdce';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 2: ", result);
        
        // assert
        expect(result).toBe(false);
    });
    
    it('returns true whenno duplicates and is ascending a - z order ', () => {
        // arrange
        const str = 'ace';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 3: ", result);
        
        // assert
        expect(result).toBe(true);
    });
    
    it('returns true whenno duplicates and is ascending a - z order ', () => {
        // arrange
        const str = 'xyza';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 4: ", result);
        
        // assert
        expect(result).toBe(false);
    });
    
     it('returns true whenno duplicates and is ascending a - z order ', () => {
        // arrange
        const str = '';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 5: ", result);
        
        // assert
        expect(result).toBe(false);
    });
    
     it('returns true whenno duplicates and is ascending a - z order ', () => {
        // arrange
        const str = null
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 5: ", result);
        
        // assert
        expect(result).toBe(false);
    });
    
     it('returns true whenno duplicates and is ascending a - z order ', () => {
        // arrange
        const str = 'ab xyz';
        
        // act
        const result = alphabetSubsequence(str);

        // log
        console.log("result 6: ", result);
        
        // assert
        expect(result).toBe(true);
    });
});