add test for pathops simplify bug workaround

Tests/ttLib/removeOverlaps_test.py

@@ -0,0 +1,53 @@
+import logging
+from fontTools.ttLib.removeOverlaps import _simplify
+import pathops
+import pytest
+
+
+def test_pathops_simplify_bug_workaround(caplog):
+    # Paths extracted from Noto Sans Ethiopic instance that fails skia-pathops
+    # https://github.com/google/fonts/issues/3365
+    # https://bugs.chromium.org/p/skia/issues/detail?id=11958
+    path = pathops.Path()
+    path.moveTo(550.461, 0)
+    path.lineTo(550.461, 366.308)
+    path.lineTo(713.229, 366.308)
+    path.lineTo(713.229, 0)
+    path.close()
+    path.moveTo(574.46, 0)
+    path.lineTo(574.46, 276.231)
+    path.lineTo(737.768, 276.231)
+    path.quadTo(820.075, 276.231, 859.806, 242.654)
+    path.quadTo(899.537, 209.077, 899.537, 144.154)
+    path.quadTo(899.537, 79, 853.46, 39.5)
+    path.quadTo(807.383, 0, 712.383, 0)
+    path.close()
+
+    # check that it fails without workaround
+    with pytest.raises(pathops.PathOpsError):
+        pathops.simplify(path)
+
+    # check our workaround works (but with a warning)
+    with caplog.at_level(logging.DEBUG, logger="fontTools.ttLib.removeOverlaps"):
+        result = _simplify(path, debugGlyphName="a")
+
+    assert "skia-pathops failed to simplify 'a' with float coordinates" in caplog.text
+
+    expected = pathops.Path()
+    expected.moveTo(550, 0)
+    expected.lineTo(550, 366)
+    expected.lineTo(713, 366)
+    expected.lineTo(713, 276)
+    expected.lineTo(738, 276)
+    expected.quadTo(820, 276, 860, 243)
+    expected.quadTo(900, 209, 900, 144)
+    expected.quadTo(900, 79, 853, 40)
+    expected.quadTo(807.242, 0.211, 713, 0.001)
+    expected.lineTo(713, 0)
+    expected.close()
+
+    rounded_result = pathops.Path()
+    for verb, pts in result:
+        rounded_result.add(verb, *((round(p[0], 3), round(p[1], 3)) for p in pts))
+
+    assert expected == rounded_result