[LayoutNG] Add forced breakpoint tests

Break-before, break-after, and break-inside don't apply to absolute
positioned elements, so we don't need to add any special handling for
these when fragmenting OOF positioned elements. This change adds tests
to ensure that these forced breaks don't apply to abspos elements, as
expected, but do still apply to the children of abspos elements.

Bug: 1079031
Change-Id: Iaee4dfa67244e1999f659978c7cb3bbfce55ad8d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2327818
Commit-Queue: Alison Maher <almaher@microsoft.com>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795544}

third_party/blink/renderer/core/layout/ng/ng_out_of_flow_layout_part_test.cc

@@ -317,5 +317,253 @@ TEST_F(NGOutOfFlowLayoutPartTest, PositionedFragmentationWithNewEmptyColumns) {
   EXPECT_EQ(expectation, dump);
 }
 
+// Break-inside does not apply to absolute positioned elements.
+TEST_F(NGOutOfFlowLayoutPartTest, BreakInsideAvoid) {
+  SetBodyInnerHTML(
+      R"HTML(
+      <style>
+        #multicol {
+          column-count:2; column-fill:auto; column-gap:16px; height:40px;
+        }
+        .rel {
+          position: relative;
+        }
+        .abs {
+          position:absolute; break-inside:avoid;
+        }
+      </style>
+      <div id="container">
+        <div id="multicol">
+          <div style="width:20px; height:10px;"></div>
+          <div class="rel" style="width:30px;">
+            <div class="abs" style="width:40px; height:40px;"></div>
+          </div>
+        </div>
+      </div>
+      )HTML");
+  String dump = DumpFragmentTree(GetElementById("container"));
+
+  // TODO(bebeaudr): The abspos should have an offset of (0,10), and
+  // break into a second column, ignoring "break-inside:avoid".
+  String expectation = R"DUMP(.:: LayoutNG Physical Fragment Tree ::.
+  offset:unplaced size:1000x40
+    offset:0,0 size:1000x40
+      offset:0,0 size:492x40
+        offset:0,0 size:20x10
+        offset:0,10 size:30x0
+        offset:0,0 size:40x40
+)DUMP";
+  EXPECT_EQ(expectation, dump);
+}
+
+// Break-before does not apply to absolute positioned elements.
+TEST_F(NGOutOfFlowLayoutPartTest, BreakBeforeColumn) {
+  SetBodyInnerHTML(
+      R"HTML(
+      <style>
+        #multicol {
+          column-count:2; column-fill:auto; column-gap:16px; height:40px;
+        }
+        .rel {
+          position: relative;
+        }
+        .abs {
+          position:absolute; break-before:column;
+        }
+      </style>
+      <div id="container">
+        <div id="multicol">
+          <div style="width:10px; height:30px;"></div>
+          <div class="rel" style="width:30px;">
+            <div class="abs" style="width:40px; height:30px;"></div>
+          </div>
+        </div>
+      </div>
+      )HTML");
+  String dump = DumpFragmentTree(GetElementById("container"));
+
+  // TODO(bebeaudr): The abspos should have an offset of (0,30) in the first
+  // column, ignoring "break-before:column", and break into a second column.
+  String expectation = R"DUMP(.:: LayoutNG Physical Fragment Tree ::.
+  offset:unplaced size:1000x40
+    offset:0,0 size:1000x40
+      offset:0,0 size:492x40
+        offset:0,0 size:10x30
+        offset:0,30 size:30x0
+        offset:0,0 size:40x30
+)DUMP";
+  EXPECT_EQ(expectation, dump);
+}
+
+// Break-after does not apply to absolute positioned elements.
+TEST_F(NGOutOfFlowLayoutPartTest, BreakAfterColumn) {
+  SetBodyInnerHTML(
+      R"HTML(
+      <style>
+        #multicol {
+          column-count:2; column-fill:auto; column-gap:16px; height:40px;
+        }
+        .rel {
+          position: relative;
+        }
+        .abs {
+          position:absolute; break-after:column;
+        }
+      </style>
+      <div id="container">
+        <div id="multicol">
+          <div style="width:10px; height:20px;"></div>
+          <div class="rel" style="width:30px; height:10px;">
+            <div class="abs" style="width:40px; height:10px;"></div>
+          </div>
+          <div style="width:20px; height:10px;"></div>
+        </div>
+      </div>
+      )HTML");
+  String dump = DumpFragmentTree(GetElementById("container"));
+
+  // TODO(bebeaudr): The abspos should have an offset of (0,20).
+  String expectation = R"DUMP(.:: LayoutNG Physical Fragment Tree ::.
+  offset:unplaced size:1000x40
+    offset:0,0 size:1000x40
+      offset:0,0 size:492x40
+        offset:0,0 size:10x20
+        offset:0,20 size:30x10
+        offset:0,30 size:20x10
+        offset:0,0 size:40x10
+)DUMP";
+  EXPECT_EQ(expectation, dump);
+}
+
+// Break-inside should still apply to children of absolute positioned elements.
+TEST_F(NGOutOfFlowLayoutPartTest, ChildBreakInsideAvoid) {
+  SetBodyInnerHTML(
+      R"HTML(
+      <style>
+        #multicol {
+          column-count:2; column-fill:auto; column-gap:16px; height:100px;
+        }
+        .rel {
+          position: relative;
+        }
+        .abs {
+          position:absolute;
+        }
+      </style>
+      <div id="container">
+        <div id="multicol">
+          <div class="rel" style="width:30px;">
+            <div class="abs" style="width:40px; height:150px;">
+              <div style="width:15px; height:50px;"></div>
+              <div style="break-inside:avoid; width:20px; height:100px;"></div>
+            </div>
+          </div>
+        </div>
+      </div>
+      )HTML");
+  String dump = DumpFragmentTree(GetElementById("container"));
+
+  String expectation = R"DUMP(.:: LayoutNG Physical Fragment Tree ::.
+  offset:unplaced size:1000x100
+    offset:0,0 size:1000x100
+      offset:0,0 size:492x100
+        offset:0,0 size:30x0
+        offset:0,0 size:40x100
+          offset:0,0 size:15x50
+      offset:508,0 size:492x100
+        offset:0,0 size:40x50
+          offset:0,0 size:20x100
+)DUMP";
+  EXPECT_EQ(expectation, dump);
+}
+
+// Break-before should still apply to children of absolute positioned elements.
+TEST_F(NGOutOfFlowLayoutPartTest, ChildBreakBeforeAvoid) {
+  SetBodyInnerHTML(
+      R"HTML(
+      <style>
+        #multicol {
+          column-count:2; column-fill:auto; column-gap:16px; height:100px;
+        }
+        .rel {
+          position: relative;
+        }
+        .abs {
+          position:absolute;
+        }
+      </style>
+      <div id="container">
+        <div id="multicol">
+          <div class="rel" style="width:30px;">
+            <div class="abs" style="width:40px; height:150px;">
+              <div style="width:15px; height:50px;"></div>
+              <div style="width:20px; height:50px;"></div>
+              <div style="break-before:avoid; width:10px; height:20px;"></div>
+            </div>
+          </div>
+        </div>
+      </div>
+      )HTML");
+  String dump = DumpFragmentTree(GetElementById("container"));
+
+  String expectation = R"DUMP(.:: LayoutNG Physical Fragment Tree ::.
+  offset:unplaced size:1000x100
+    offset:0,0 size:1000x100
+      offset:0,0 size:492x100
+        offset:0,0 size:30x0
+        offset:0,0 size:40x100
+          offset:0,0 size:15x50
+      offset:508,0 size:492x100
+        offset:0,0 size:40x50
+          offset:0,0 size:20x50
+          offset:0,50 size:10x20
+)DUMP";
+  EXPECT_EQ(expectation, dump);
+}
+
+// Break-after should still apply to children of absolute positioned elements.
+TEST_F(NGOutOfFlowLayoutPartTest, ChildBreakAfterAvoid) {
+  SetBodyInnerHTML(
+      R"HTML(
+      <style>
+        #multicol {
+          column-count:2; column-fill:auto; column-gap:16px; height:100px;
+        }
+        .rel {
+          position: relative;
+        }
+        .abs {
+          position:absolute;
+        }
+      </style>
+      <div id="container">
+        <div id="multicol">
+          <div class="rel" style="width:30px;">
+            <div class="abs" style="width:40px; height:150px;">
+              <div style="width:15px; height:50px;"></div>
+              <div style="break-after:avoid; width:20px; height:50px;"></div>
+              <div style="width:10px; height:20px;"></div>
+            </div>
+          </div>
+        </div>
+      </div>
+      )HTML");
+  String dump = DumpFragmentTree(GetElementById("container"));
+
+  String expectation = R"DUMP(.:: LayoutNG Physical Fragment Tree ::.
+  offset:unplaced size:1000x100
+    offset:0,0 size:1000x100
+      offset:0,0 size:492x100
+        offset:0,0 size:30x0
+        offset:0,0 size:40x100
+          offset:0,0 size:15x50
+      offset:508,0 size:492x100
+        offset:0,0 size:40x50
+          offset:0,0 size:20x50
+          offset:0,50 size:10x20
+)DUMP";
+  EXPECT_EQ(expectation, dump);
+}
+
 }  // namespace
 }  // namespace blink