[varLib.featureVars] Add quadratic test

We get the optimal solution.

Tests/varLib/featureVars_test.py

@@ -4,34 +4,56 @@ from fontTools.varLib.featureVars import (
     overlayFeatureVariations)
 
 
-def test_explosion(n = 10):
+def test_linear(n = 10):
     conds = []
     for i in range(n):
         end = i / n
         start = end - 1.
-        region = [{'axis': (start, end)}]
+        region = [{'X': (start, end)}]
         subst = {'g%.2g'%start: 'g%.2g'%end}
         conds.append((region, subst))
     overlaps = overlayFeatureVariations(conds)
     assert len(overlaps) == 2 * n - 1, overlaps
     return conds, overlaps
 
-if __name__ == "__main__":
-    import sys
-    from pprint import pprint
-    quiet = False
-    args = {}
-    if len(sys.argv) > 1:
-        if sys.argv[1] == '-q':
-            quiet = True
-            del sys.argv[1]
-        args['n'] = int(sys.argv[1])
-    input, output = test_explosion(**args)
+def test_quadratic(n = 10):
+    conds = []
+    for i in range(1, n + 1):
+        region = [{'X': (0, i / n),
+                   'Y': (0, (n + 1 - i) / n)}]
+        subst = {str(i): str(n + 1 - i)}
+        conds.append((region, subst))
+    overlaps = overlayFeatureVariations(conds)
+    assert len(overlaps) == n * (n + 1) // 2, overlaps
+    return conds, overlaps
+
+
+def run(test, n, quiet):
+
+    print()
+    print("%s:" % test.__name__)
+    input, output = test(n)
     if quiet:
         print(len(output))
     else:
+        print()
         print("Input:")
         pprint(input)
         print()
         print("Output:")
         pprint(output)
+        print()
+
+if __name__ == "__main__":
+    import sys
+    from pprint import pprint
+    quiet = False
+    n = 3
+    if len(sys.argv) > 1 and sys.argv[1] == '-q':
+        quiet = True
+        del sys.argv[1]
+    if len(sys.argv) > 1:
+        n = int(sys.argv[1])
+
+    run(test_linear, n=n, quiet=quiet)
+    run(test_quadratic, n=n, quiet=quiet)