harden and speed up path op unit tests

tests/PathOpsDVectorTest.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+#include "PathOpsTestCommon.h"
 #include "SkPathOpsPoint.h"
 #include "Test.h"
 
 static const SkDPoint tests[] = {
     {0, 0},
     {1, 0},
     {0, 1},
     {2, 1},
     {1, 2},
     {1, 1},
     {2, 2}
 };
 
 static const size_t tests_count = SK_ARRAY_COUNT(tests);
 
 static void PathOpsDVectorTest(skiatest::Reporter* reporter) {
     for (size_t index = 0; index < tests_count - 1; ++index) {
         SkDVector v1 = tests[index + 1] - tests[index];
+        SkASSERT(ValidVector(v1));
         SkDVector v2 = tests[index] - tests[index + 1];
+        SkASSERT(ValidVector(v2));
         v1 += v2;
         REPORTER_ASSERT(reporter, v1.fX == 0 && v1.fY == 0);
         SkDPoint p = tests[index + 1] + v2;
         REPORTER_ASSERT(reporter, p == tests[index]);
         v2 -= v2;
         REPORTER_ASSERT(reporter, v2.fX == 0 && v2.fY == 0);
         v1 = tests[index + 1] - tests[index];
         v1 /= 2;
         v1 *= 2;
         v1 -= tests[index + 1] - tests[index];
         REPORTER_ASSERT(reporter, v1.fX == 0 && v1.fY == 0);
         SkVector sv = v1.asSkVector();
         REPORTER_ASSERT(reporter, sv.fX == 0 && sv.fY == 0);
         v1 = tests[index + 1] - tests[index];
         double lenSq = v1.lengthSquared();
         double v1Dot = v1.dot(v1);
         REPORTER_ASSERT(reporter, lenSq == v1Dot);
         REPORTER_ASSERT(reporter, approximately_equal(sqrt(lenSq), v1.length()));
         double v1Cross = v1.cross(v1);
         REPORTER_ASSERT(reporter, v1Cross == 0);
     }
 }
 
 #include "TestClassDef.h"
 DEFINE_TESTCLASS_SHORT(PathOpsDVectorTest)