From 5b3176f4fdc27505700594cb93f83fa51253db1d Mon Sep 17 00:00:00 2001
From: Cosimo Lupo <clupo@google.com>
Date: Tue, 4 Feb 2025 10:20:41 +0000
Subject: [PATCH] add test for parsing and compiling DeviceTable's DeltaValue

---
 Lib/fontTools/misc/testTools.py     |  3 +
 Tests/ttLib/tables/otTables_test.py | 88 +++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)

diff --git a/Lib/fontTools/misc/testTools.py b/Lib/fontTools/misc/testTools.py
index 7d7872148..f4127fe61 100644
--- a/Lib/fontTools/misc/testTools.py
+++ b/Lib/fontTools/misc/testTools.py
@@ -58,6 +58,9 @@ class FakeFont:
         self.tables = {}
         self.cfg = Config()
 
+    def __contains__(self, tag):
+        return tag in self.tables
+
     def __getitem__(self, tag):
         return self.tables[tag]
 
diff --git a/Tests/ttLib/tables/otTables_test.py b/Tests/ttLib/tables/otTables_test.py
index db33e4c65..01bc97db8 100644
--- a/Tests/ttLib/tables/otTables_test.py
+++ b/Tests/ttLib/tables/otTables_test.py
@@ -4,6 +4,7 @@ from fontTools.misc.xmlWriter import XMLWriter
 from fontTools.ttLib.tables.otBase import OTTableReader, OTTableWriter
 import fontTools.ttLib.tables.otTables as otTables
 from io import StringIO
+from textwrap import dedent
 import unittest
 
 
@@ -735,6 +736,93 @@ class ColrV1Test(unittest.TestCase):
         assert len(visited) == 1
 
 
+def test_parse_Device_DeltaValue_from_XML_and_compile():
+    # https://github.com/fonttools/fonttools/pull/3757
+    font = FakeFont([".notdef", "five"])
+
+    gpos_xml = dedent(
+        """\
+        <Version value="0x00010000"/>
+        <ScriptList>
+          <!-- ScriptCount=1 -->
+          <ScriptRecord index="0">
+            <ScriptTag value="DFLT"/>
+            <Script>
+              <DefaultLangSys>
+                <ReqFeatureIndex value="65535"/>
+                <!-- FeatureCount=1 -->
+                <FeatureIndex index="0" value="0"/>
+              </DefaultLangSys>
+              <!-- LangSysCount=0 -->
+            </Script>
+          </ScriptRecord>
+        </ScriptList>
+        <FeatureList>
+          <!-- FeatureCount=1 -->
+          <FeatureRecord index="0">
+            <FeatureTag value="curs"/>
+            <Feature>
+              <!-- LookupCount=1 -->
+              <LookupListIndex index="0" value="0"/>
+            </Feature>
+          </FeatureRecord>
+        </FeatureList>
+        <LookupList>
+          <!-- LookupCount=1 -->
+          <Lookup index="0">
+            <LookupType value="3"/>
+            <LookupFlag value="0"/>
+            <!-- SubTableCount=1 -->
+            <CursivePos index="0" Format="1">
+              <Coverage>
+                <Glyph value="five"/>
+              </Coverage>
+              <!-- EntryExitCount=1 -->
+              <EntryExitRecord index="0">
+                <EntryAnchor Format="3">
+                  <XCoordinate value="124"/>
+                  <YCoordinate value="-4"/>
+                  <XDeviceTable>
+                    <StartSize value="8"/>
+                    <EndSize value="9"/>
+                    <DeltaFormat value="2"/>
+                    <DeltaValue value="[1, 2]"/>
+                  </XDeviceTable>
+                  <YDeviceTable>
+                    <StartSize value="7"/>
+                    <EndSize value="7"/>
+                    <DeltaFormat value="2"/>
+                    <DeltaValue value="[3]"/>
+                  </YDeviceTable>
+                </EntryAnchor>
+                <ExitAnchor Format="2">
+                  <XCoordinate value="3"/>
+                  <YCoordinate value="4"/>
+                  <AnchorPoint value="2"/>
+                </ExitAnchor>
+              </EntryExitRecord>
+            </CursivePos>
+          </Lookup>
+        </LookupList>"""
+    )
+
+    gpos = parseXmlInto(font, otTables.GPOS(), gpos_xml)
+
+    anchor = gpos.LookupList.Lookup[0].SubTable[0].EntryExitRecord[0].EntryAnchor
+    assert anchor.XDeviceTable.DeltaValue == [1, 2]
+    assert anchor.YDeviceTable.DeltaValue == [3]
+
+    writer = OTTableWriter()
+    gpos.compile(writer, font)
+    data = writer.getAllData()
+
+    reader = OTTableReader(data, tableTag="GPOS")
+    gpos2 = otTables.GPOS()
+    gpos2.decompile(reader, font)
+
+    assert dedent("\n".join(getXML(gpos2.toXML, font)[1:-1])) == gpos_xml
+
+
 if __name__ == "__main__":
     import sys