diff --git a/Tests/varLib/data/IncompatibleFeatures.designspace b/Tests/varLib/data/IncompatibleFeatures.designspace
new file mode 100644
index 000000000..ab275164a
--- /dev/null
+++ b/Tests/varLib/data/IncompatibleFeatures.designspace
@@ -0,0 +1,22 @@
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diff --git a/Tests/varLib/data/master_incompatible_features/IncompatibleFeatures-Bold.ttx b/Tests/varLib/data/master_incompatible_features/IncompatibleFeatures-Bold.ttx
new file mode 100644
index 000000000..a1803e9e9
--- /dev/null
+++ b/Tests/varLib/data/master_incompatible_features/IncompatibleFeatures-Bold.ttx
@@ -0,0 +1,578 @@
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+ 1.000;NONE;SimpleTwoAxis-Bold
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diff --git a/Tests/varLib/data/master_incompatible_features/IncompatibleFeatures-Regular.ttx b/Tests/varLib/data/master_incompatible_features/IncompatibleFeatures-Regular.ttx
new file mode 100644
index 000000000..7186a3e97
--- /dev/null
+++ b/Tests/varLib/data/master_incompatible_features/IncompatibleFeatures-Regular.ttx
@@ -0,0 +1,626 @@
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+ 1.000;NONE;SimpleTwoAxis-Regular
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+ Version 1.000
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+ SimpleTwoAxis-Regular
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diff --git a/Tests/varLib/varLib_test.py b/Tests/varLib/varLib_test.py
index da1f94f4a..76d951def 100644
--- a/Tests/varLib/varLib_test.py
+++ b/Tests/varLib/varLib_test.py
@@ -1,7 +1,7 @@
from fontTools.misc.py23 import *
from fontTools.ttLib import TTFont, newTable
from fontTools.varLib import build, load_designspace
-from fontTools.varLib.errors import VarLibValidationError
+from fontTools.varLib.errors import VarLibValidationError, VarLibMergeError
from fontTools.varLib.mutator import instantiateVariableFont
from fontTools.varLib import main as varLib_main, load_masters
from fontTools.varLib import set_default_weight_width_slant
@@ -813,7 +813,32 @@ class BuildTest(unittest.TestCase):
assert ds_loaded.instances[0].location == {"weight": 0, "width": 50}
+ def test_varlib_build_incompatible_features(self):
+ try:
+ self._run_varlib_build_test(
+ designspace_name="IncompatibleFeatures",
+ font_name="IncompatibleFeatures",
+ tables=["GPOS"],
+ expected_ttx_name="IncompatibleFeatures",
+ save_before_dump=True,
+ )
+ except VarLibMergeError as e:
+ assert str(e) == """
+Couldn't merge the fonts, because some values were different, but should have
+been the same. This happened while performing the following operation:
+GPOS.table.FeatureList.FeatureCount
+
+The problem is likely to be in Simple Two Axis Bold:
+
+Incompatible features between masters.
+Expected: kern, mark.
+Got: kern.
+"""
+ except Exception:
+ self.fail('unexpected exception raised')
+ else:
+ self.fail('ExpectedException not raised')
def test_load_masters_layerName_without_required_font():
ds = DesignSpaceDocument()
s = SourceDescriptor()