private static void TestIntervalOps(S1Interval x, S1Interval y, string expected_relation, S1Interval expected_union, S1Interval expected_intersection)
{
// Test all of the interval operations on the given pair of intervals.
// "expected_relation" is a sequence of "T" and "F" characters corresponding
// to the expected results of Contains(), InteriorContains(), Intersects(),
// and InteriorIntersects() respectively.
Assert.Equal(x.Contains(y), expected_relation[0] == 'T');
Assert.Equal(x.InteriorContains(y), expected_relation[1] == 'T');
Assert.Equal(x.Intersects(y), expected_relation[2] == 'T');
Assert.Equal(x.InteriorIntersects(y), expected_relation[3] == 'T');
// bounds() returns a reference to a member variable, so we need to
// make a copy when invoking it on a temporary object.
Assert.Equal(R2Point.FromCoords(x.Union(y).Bounds()).Bounds(), expected_union.Bounds());
Assert.Equal(R2Point.FromCoords(x.Intersection(y).Bounds()).Bounds(),
expected_intersection.Bounds());
Assert.Equal(x.Contains(y), x.Union(y) == x);
Assert.Equal(x.Intersects(y), !x.Intersection(y).IsEmpty());
if (y.Lo == y.Hi)
{
var r = S1Interval.AddPoint(x, y.Lo);
Assert.Equal(r.Bounds(), expected_union.Bounds());
}
}