added missing test file

tests/ic/mmethupref.nim

@@ -0,0 +1,23 @@
+# Helper for tmethupref: a `{.base.}` method whose body contains a closure
+# iterator that in turn contains a nested closure capturing a method-local.
+# The capture forces an `up` reference chain (nested closure -> iterator env ->
+# method env). The method also gets a dispatcher (a `copySym` clone that shares
+# the method's body sub-tree, including the iterator). Under `nim ic` the
+# dispatcher used to be treated as an owned runtime routine and lambda-lifted in
+# the per-module lower stage, lifting the SHARED iterator a second time under a
+# different owner identity -> "up references do not agree" / "could not determine
+# closure type". See nifbackend.ownsRuntimeRoutine (sfDispatcher exclusion).
+
+type Base* = ref object of RootObj
+  val*: int
+
+method compute*(b: Base): int {.base.} =
+  var acc = b.val
+  iterator steps(): int {.closure.} =
+    proc bump() =
+      acc += 1
+    bump()
+    bump()
+    yield acc
+  for s in steps():
+    result = s