1 files changed, 58 insertions, 1 deletions
diff --git a/Tests/varLib/varLib_test.py b/Tests/varLib/varLib_test.py
index da1f94f4..b8e7183b 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
+import fontTools.varLib.errors as varLibErrors
 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
@@ -10,6 +10,7 @@ from fontTools.designspaceLib import (
 )
 from fontTools.feaLib.builder import addOpenTypeFeaturesFromString
 import difflib
+from io import BytesIO
 import os
 import shutil
 import sys
@@ -813,6 +814,62 @@ class BuildTest(unittest.TestCase):
 
         assert ds_loaded.instances[0].location == {"weight": 0, "width": 50}
 
+    def test_varlib_build_incompatible_features(self):
+        with pytest.raises(
+            varLibErrors.ShouldBeConstant,
+            match = """
+
+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.
+"""):
+
+            self._run_varlib_build_test(
+                designspace_name="IncompatibleFeatures",
+                font_name="IncompatibleFeatures",
+                tables=["GPOS"],
+                expected_ttx_name="IncompatibleFeatures",
+                save_before_dump=True,
+            )
+
+    def test_varlib_build_incompatible_lookup_types(self):
+        with pytest.raises(
+            varLibErrors.MismatchedTypes,
+            match = r"MarkBasePos, instead saw PairPos"
+        ):
+            self._run_varlib_build_test(
+                designspace_name="IncompatibleLookupTypes",
+                font_name="IncompatibleLookupTypes",
+                tables=["GPOS"],
+                expected_ttx_name="IncompatibleLookupTypes",
+                save_before_dump=True,
+            )
+
+    def test_varlib_build_incompatible_arrays(self):
+        with pytest.raises(
+            varLibErrors.ShouldBeConstant,
+            match = """
+
+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.ScriptList.ScriptCount
+
+The problem is likely to be in Simple Two Axis Bold:
+Expected to see .ScriptCount==1, instead saw 0"""
+        ):
+            self._run_varlib_build_test(
+                designspace_name="IncompatibleArrays",
+                font_name="IncompatibleArrays",
+                tables=["GPOS"],
+                expected_ttx_name="IncompatibleArrays",
+                save_before_dump=True,
+            )
 
 def test_load_masters_layerName_without_required_font():
     ds = DesignSpaceDocument()