static PolygonXorFacts() {
     _polyPairData = PolyOperationTestUtility.GeneratePolyPairXorTestDataCollection();
     _xorOperation = new PolygonXorOperation();
 }
 static PolygonUnionFacts() {
     _polyPairData = PolyOperationTestUtility.GeneratePolyPairUnionTestDataCollection();
     _unionOperation = new PolygonUnionOperation();
 }
 static PolygonIntersectionFacts() {
     _polyPairData = PolyOperationTestUtility.GeneratePolyPairIntersectionTestDataCollection();
     _intersectionOperation = new PolygonIntersectionOperation();
 }
 static PolygonDifferenceFacts() {
     _polyPairData = PolyOperationTestUtility.GeneratePolyPairDifferenceTestDataCollection();
     _differenceOperation = new PolygonDifferenceOperation();
 }