🐐 Step in for loop

tests.py

@@ -894,6 +894,8 @@ error_tests = [
   ('CVM RETE\nAVSCVLTA(LXXX)', CentvrionError),                               # AVSCVLTA: no routes registered
   ('AVSCVLTA(LXXX)', CentvrionError),                                         # RETE required for AVSCVLTA
   ('CVM RETE\nPETITVR("/", FVNCTIO (r) VT {\nREDI("hi")\n})\nAVSCVLTA("text")', CentvrionError),  # AVSCVLTA port must be integer
+  ("DONICVM i VT I VSQVE X GRADV I - I FAC { DIC(i) }", CentvrionError),  # GRADV zero step
+  ('DONICVM i VT I VSQVE X GRADV "foo" FAC { DIC(i) }', CentvrionError),  # GRADV non-integer step
 ]
 
 class TestErrors(unittest.TestCase):
@@ -1705,6 +1707,90 @@ loop_edge_tests = [
       ExpressionStatement(Invoca(ID("f"), [])),
     ]),
     ValInt(4)),  # returns b=IV when a=III
+  # DONICVM GRADV II, endpoint hit exactly: [I, III, V]
+  ("DONICVM i VT I VSQVE V GRADV II FAC { DIC(i) }",
+    Program([], [PerStatement(
+      DataRangeArray(Numeral("I"), Numeral("V"), Numeral("II")),
+      ID("i"),
+      [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("V"), "I\nIII\nV\n"),
+  # DONICVM GRADV II, endpoint overshot: VI excluded, stops at V
+  ("DONICVM i VT I VSQVE VI GRADV II FAC { DIC(i) }",
+    Program([], [PerStatement(
+      DataRangeArray(Numeral("I"), Numeral("VI"), Numeral("II")),
+      ID("i"),
+      [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("V"), "I\nIII\nV\n"),
+  # DONICVM GRADV I is equivalent to default step
+  ("DONICVM i VT I VSQVE III GRADV I FAC { DIC(i) }",
+    Program([], [PerStatement(
+      DataRangeArray(Numeral("I"), Numeral("III"), Numeral("I")),
+      ID("i"),
+      [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("III"), "I\nII\nIII\n"),
+  # DONICVM descending by I
+  ("CVM SVBNVLLA\nDONICVM i VT V VSQVE I GRADV - I FAC { DIC(i) }",
+    Program([ModuleCall("SVBNVLLA")], [PerStatement(
+      DataRangeArray(Numeral("V"), Numeral("I"), UnaryMinus(Numeral("I"))),
+      ID("i"),
+      [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("I"), "V\nIV\nIII\nII\nI\n"),
+  # DONICVM descending by II, endpoint overshot
+  ("CVM SVBNVLLA\nDONICVM i VT X VSQVE I GRADV - II FAC { DIC(i) }",
+    Program([ModuleCall("SVBNVLLA")], [PerStatement(
+      DataRangeArray(Numeral("X"), Numeral("I"), UnaryMinus(Numeral("II"))),
+      ID("i"),
+      [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("II"), "X\nVIII\nVI\nIV\nII\n"),
+  # DONICVM with step bound to a variable
+  ("DESIGNA s VT II\nDONICVM i VT I VSQVE V GRADV s FAC { DIC(i) }",
+    Program([], [
+      Designa(ID("s"), Numeral("II")),
+      PerStatement(
+        DataRangeArray(Numeral("I"), Numeral("V"), ID("s")),
+        ID("i"),
+        [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("V"), "I\nIII\nV\n"),
+  # DONICVM from == to with nonzero step: single iteration
+  ("DONICVM i VT III VSQVE III GRADV II FAC { DIC(i) }",
+    Program([], [PerStatement(
+      DataRangeArray(Numeral("III"), Numeral("III"), Numeral("II")),
+      ID("i"),
+      [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("III"), "III\n"),
+  # DONICVM direction mismatch — negative step with ascending bounds: body never runs
+  ("CVM SVBNVLLA\nDESIGNA x VT NVLLVS\nDONICVM i VT I VSQVE X GRADV - I FAC { DESIGNA x VT x + i }\nx",
+    Program([ModuleCall("SVBNVLLA")], [
+      Designa(ID("x"), Nullus()),
+      PerStatement(
+        DataRangeArray(Numeral("I"), Numeral("X"), UnaryMinus(Numeral("I"))),
+        ID("i"),
+        [Designa(ID("x"), BinOp(ID("x"), ID("i"), "SYMBOL_PLUS"))]),
+      ExpressionStatement(ID("x"))]),
+    ValNul(), ""),
+  # Range-array literal with GRADV used via PER
+  ("PER i IN [I VSQVE V GRADV II] FAC { DIC(i) }",
+    Program([], [PerStatement(
+      DataRangeArray(Numeral("I"), Numeral("V"), Numeral("II")),
+      ID("i"),
+      [ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("V"), "I\nIII\nV\n"),
+  # DONICVM GRADV II with CONTINVA: skip value V, print the others
+  ("DONICVM i VT I VSQVE IX GRADV II FAC {\nSI i EST V TVNC { CONTINVA }\nDIC(i)\n}",
+    Program([], [PerStatement(
+      DataRangeArray(Numeral("I"), Numeral("IX"), Numeral("II")),
+      ID("i"),
+      [SiStatement(BinOp(ID("i"), Numeral("V"), "KEYWORD_EST"), [Continva()], None),
+       ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("IX"), "I\nIII\nVII\nIX\n"),
+  # DONICVM GRADV II with ERVMPE: stop at V (last successful DIC was III)
+  ("DONICVM i VT I VSQVE IX GRADV II FAC {\nSI i EST V TVNC { ERVMPE }\nDIC(i)\n}",
+    Program([], [PerStatement(
+      DataRangeArray(Numeral("I"), Numeral("IX"), Numeral("II")),
+      ID("i"),
+      [SiStatement(BinOp(ID("i"), Numeral("V"), "KEYWORD_EST"), [Erumpe()], None),
+       ExpressionStatement(BuiltIn("DIC", [ID("i")]))])]),
+    ValStr("III"), "I\nIII\n"),
 ]
 
 class TestLoopEdge(unittest.TestCase):