An isosceles triangle has at least two sides the same length. (It is sometimes specified as having exactly two sides the same length, but for the purposes of this exercise we’ll say at least two.)
The test that fail is like this
procedure IsoscelesTests.FirstTriangleInequalityViolation; begin Assert.AreEqual(false, Triangle.Sides(Isosceles, 1, 1, 3)); end;
A triangle with sides 1,1 and 3 have 2 sides equal. So isn’t that Isosceles and true result is expected ?