code from my first visit to Dayton Clean Coders, an implementation of the kata at http://onestepback.org/vital_testing/

implementation of TriangleClassifier

// implementation of the challenge found here: http://onestepback.org/vital_testing/

var TriangleClassifier = { 
  
  valid : function (args) {
    var sides = [ args[0], args[1], args[2] ];
    
    if (args.length != 3) {
      return false;
    }
    
    for (var i = 0; i < sides.length; i++){
      if (sides[i] <= 0 || typeof sides[i] != 'number') {
        return false;
      }
    }
    
    sides.sort();
    if (sides[0] + sides[1] <= sides[2] ) {
      return false;
    }
    
    return true;
  },
  
  classify : function(len1, len2, len3) {
    
    if ( !TriangleClassifier.valid(arguments) ) {
      return "ArgumentError";
    }
    
    if (len1 == len2 && len2 == len3 ) {
      return ":equilateral";
    }
    
    if (len1 == len2 || len2 == len3 || len3 == len1) {
      return ":isosceles";
    }
    
    return ":scalene";
    
  },
}

tests for TriangleClassifier

describe('equilateral has 3 equal sides',function(){
  it('has equal sides', function() {
    expect( 
      TriangleClassifier.classify(3, 3, 3) 
    ).toBe(':equilateral');
  });
});

describe('isosceles has two equals sides',function(){
  it('has two equal sides', function() {
    expect(
      TriangleClassifier.classify(3,3,2)
    ).toBe(':isosceles');
  });
  
});

describe('scalene has no equals sides',function(){
  it('has no equal sides', function() {
    expect(
      TriangleClassifier.classify(2,3,4)
    ).toBe(':scalene');
  });
});

describe('sides are not of a triangle',function(){

    it('raises ArgumentError for a negative length side', function() {
    expect(
      TriangleClassifier.classify(-1,1,5)
    ).toBe('ArgumentError');
  });

  it('raises ArgumentError for a zero length side', function() {
    expect(
      TriangleClassifier.classify(0,1,5)
    ).toBe('ArgumentError');
  });
  
  it('raises ArgumentError for invalid triangle', function() {
    expect(
      TriangleClassifier.classify(2,2,4)
    ).toBe('ArgumentError');
  });
  
  it('raises ArgumentError for less than 3 sides', function() {
    expect(
      TriangleClassifier.classify(2,2)
    ).toBe('ArgumentError');
  });
  
  it('raises ArgumentError for more than 3 sides', function() {
    expect(
      TriangleClassifier.classify(3,4,5,6)
    ).toBe('ArgumentError');
  });
  
    
  
  it('raises ArgumentError for invalid data type for a sides', function() {
    expect(
      TriangleClassifier.classify(3,4,'5')
    ).toBe('ArgumentError');
  });
  
});