From 07096d4af47b7b7aa2e34934d3182bac75560dbc Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 3 Feb 2023 14:02:08 -0700
Subject: [PATCH] Add test for compile/decompile toXML/fromXML of VarComposites

---
 Tests/ttLib/scaleUpem_test.py | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/Tests/ttLib/scaleUpem_test.py b/Tests/ttLib/scaleUpem_test.py
index a403cf1f2..7b4a706d3 100644
--- a/Tests/ttLib/scaleUpem_test.py
+++ b/Tests/ttLib/scaleUpem_test.py
@@ -2,6 +2,7 @@ from fontTools.ttLib import TTFont
 from fontTools.ttLib.scaleUpem import scale_upem
 import difflib
 import os
+from io import BytesIO
 import shutil
 import sys
 import tempfile
@@ -75,9 +76,24 @@ class ScaleUpemTest(unittest.TestCase):
         expected_ttx_path = self.get_path("varc-ac00-ac01-500upem.ttx")
         self.expect_ttx(font, expected_ttx_path, tables)
 
-        # While here just test that we can read the ttx
+        # While here, test a couple roundtrips
+        tables = [
+            table_tag for table_tag in tables if table_tag not in {"maxp", "hhea"}
+        ]
+        xml = BytesIO()
+        font.saveXML(xml)
+        xml1 = BytesIO()
+        font.saveXML(xml1, tables=tables)
+        xml.seek(0)
         font = TTFont()
-        font.importXML(expected_ttx_path)
+        font.importXML(xml)
+        ttf = BytesIO()
+        font.save(ttf)
+        ttf.seek(0)
+        font = TTFont(ttf)
+        xml2 = BytesIO()
+        font.saveXML(xml2, tables=tables)
+        assert xml1.getvalue() == xml2.getvalue()
 
         # Scale our other varComposite font as well; without checking the expected
         font = TTFont(self.get_path("varc-6868.ttf"))