From 944b704a393dccd673716081b13a86d3fa59a7d4 Mon Sep 17 00:00:00 2001
From: Nick Gerleman <ngerlem@meta.com>
Date: Mon, 22 Jan 2024 15:11:50 -0800
Subject: [PATCH] Fix flooring of border (#1562)

Summary:
X-link: https://github.com/facebook/react-native/pull/42411


I added a small regression D52605596, where negative border would not be correctly floored. This fixes that, and starts adding tests specifically targeting the computed style API, now decoupled from the yoga node.

Reviewed By: joevilches

Differential Revision: D52930827
---
 tests/StyleTest.cpp | 44 ++++++++++++++++++++++++++++++++++++++++++++
 yoga/style/Style.h  | 28 ++++++++++++++++------------
 2 files changed, 60 insertions(+), 12 deletions(-)
 create mode 100644 tests/StyleTest.cpp

diff --git a/tests/StyleTest.cpp b/tests/StyleTest.cpp
new file mode 100644
index 0000000000..b0c60355e8
--- /dev/null
+++ b/tests/StyleTest.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <gtest/gtest.h>
+#include <yoga/style/Style.h>
+
+namespace facebook::yoga {
+
+TEST(Style, computed_padding_is_floored) {
+  yoga::Style style;
+  style.setPadding(Edge::All, value::points(-1.0f));
+  auto paddingStart = style.computeInlineStartPadding(
+      FlexDirection::Row, Direction::LTR, 0.0f /*widthSize*/);
+  ASSERT_EQ(paddingStart, 0.0f);
+}
+
+TEST(YogaTest, computed_border_is_floored) {
+  yoga::Style style;
+  style.setBorder(Edge::All, value::points(-1.0f));
+  auto borderStart =
+      style.computeInlineStartBorder(FlexDirection::Row, Direction::LTR);
+  ASSERT_EQ(borderStart, 0.0f);
+}
+
+TEST(YogaTest, computed_gap_is_floored) {
+  yoga::Style style;
+  style.setGap(Gutter::Column, value::points(-1.0f));
+  auto gapBetweenColumns = style.computeGapForAxis(FlexDirection::Row);
+  ASSERT_EQ(gapBetweenColumns, 0.0f);
+}
+
+TEST(YogaTest, computed_margin_is_not_floored) {
+  yoga::Style style;
+  style.setMargin(Edge::All, value::points(-1.0f));
+  auto marginStart = style.computeInlineStartMargin(
+      FlexDirection::Row, Direction::LTR, 0.0f /*widthSize*/);
+  ASSERT_EQ(marginStart, -1.0f);
+}
+
+} // namespace facebook::yoga
diff --git a/yoga/style/Style.h b/yoga/style/Style.h
index 028fcf17c1..113a8e1df1 100644
--- a/yoga/style/Style.h
+++ b/yoga/style/Style.h
@@ -312,28 +312,32 @@ class YG_EXPORT Style {
   }
 
   float computeFlexStartBorder(FlexDirection axis, Direction direction) const {
-    return computeBorder(flexStartEdge(axis), direction)
-        .resolve(0.0f)
-        .unwrapOrDefault(0.0f);
+    return maxOrDefined(
+        computeBorder(flexStartEdge(axis), direction).resolve(0.0f).unwrap(),
+        0.0f);
   }
 
   float computeInlineStartBorder(FlexDirection axis, Direction direction)
       const {
-    return computeBorder(inlineStartEdge(axis, direction), direction)
-        .resolve(0.0f)
-        .unwrapOrDefault(0.0f);
+    return maxOrDefined(
+        computeBorder(inlineStartEdge(axis, direction), direction)
+            .resolve(0.0f)
+            .unwrap(),
+        0.0f);
   }
 
   float computeFlexEndBorder(FlexDirection axis, Direction direction) const {
-    return computeBorder(flexEndEdge(axis), direction)
-        .resolve(0.0f)
-        .unwrapOrDefault(0.0f);
+    return maxOrDefined(
+        computeBorder(flexEndEdge(axis), direction).resolve(0.0f).unwrap(),
+        0.0f);
   }
 
   float computeInlineEndBorder(FlexDirection axis, Direction direction) const {
-    return computeBorder(inlineEndEdge(axis, direction), direction)
-        .resolve(0.0f)
-        .unwrapOrDefault(0.0f);
+    return maxOrDefined(
+        computeBorder(inlineEndEdge(axis, direction), direction)
+            .resolve(0.0f)
+            .unwrap(),
+        0.0f);
   }
 
   float computeFlexStartPadding(