Add more unit tests for rounding values to pixel grid (facebook#1776)

Summary:

# Changelog:
[Internal] - 

I was looking into some profiling results and noticed that Yoga has some quirky custom logic when it comes to rounding to the pixel grid, especially for the values that are halfway through.

There are already unit tests in place, but those cases weren't covered, so I am adding these extra corner cases here, to make sure they are covered in case that the actual rounding function may get modified (which it might make sense to, as it's currently can be more expensive than it could have been in some scenarios).

Differential Revision: D67712673

tests/YGRoundingFunctionTest.cpp

@@ -39,6 +39,44 @@ TEST(YogaTest, rounding_value) {
   ASSERT_FLOAT_EQ(-6.0, YGRoundValueToPixelGrid(-5.99, 2.0, false, false));
   ASSERT_FLOAT_EQ(-5.5, YGRoundValueToPixelGrid(-5.99, 2.0, true, false));
   ASSERT_FLOAT_EQ(-6.0, YGRoundValueToPixelGrid(-5.99, 2.0, false, true));
+
+  // Rounding up/down halfway values is as expected for both positive and
+  // negative numbers
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.5, 1.0, false, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.4, 1.0, false, false));
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.6, 1.0, false, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.499999, 1.0, false, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.500001, 1.0, false, false));
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.5001, 1.0, false, false));
+
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.5, 1.0, true, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.4, 1.0, true, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.6, 1.0, true, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.499999, 1.0, true, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.500001, 1.0, true, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.5001, 1.0, true, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.00001, 1.0, true, false));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3, 1.0, true, false));
+
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.5, 1.0, false, true));
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.4, 1.0, false, true));
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.6, 1.0, false, true));
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.499999, 1.0, false, true));
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.500001, 1.0, false, true));
+  ASSERT_FLOAT_EQ(-4, YGRoundValueToPixelGrid(-3.5001, 1.0, false, true));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3.00001, 1.0, false, true));
+  ASSERT_FLOAT_EQ(-3, YGRoundValueToPixelGrid(-3, 1.0, false, true));
+
+  // NAN is treated as expected:
+  ASSERT_TRUE(std::isnan(YGRoundValueToPixelGrid(
+      std::numeric_limits<double>::quiet_NaN(), 1.5, false, false)));
+  ASSERT_TRUE(std::isnan(YGRoundValueToPixelGrid(
+      1.5, std::numeric_limits<double>::quiet_NaN(), false, false)));
+  ASSERT_TRUE(std::isnan(YGRoundValueToPixelGrid(
+      std::numeric_limits<double>::quiet_NaN(),
+      std::numeric_limits<double>::quiet_NaN(),
+      false,
+      false)));
 }
 
 static YGSize measureText(