Removing mxpic_forge from dependency

tests/test_eda_router_contract.py

@@ -221,6 +221,62 @@ class EdaRouterPinsContractTest(unittest.TestCase):
         )
         self.assertEqual(_metadata_pins(metadata, r"D:\mxpic\some_project_layout"), {})
 
+    def test_route_backend_falls_back_to_nazca_interconnect_when_forge_is_absent(self):
+        import mxpic_router.builder as builder
+
+        class FakeInterconnect:
+            calls = []
+
+            def __init__(self, radius=None, width=None, xs=None, PCB=False):
+                self.radius = radius
+                self.width = width
+                self.xs = xs
+                self.PCB = PCB
+
+            def strt_p2p(self, **kwargs):
+                self.calls.append(("strt_p2p", kwargs))
+                return "straight"
+
+            def sbend_p2p(self, **kwargs):
+                self.calls.append(("sbend_p2p", kwargs))
+                return "sbend"
+
+            def ubend_p2p(self, **kwargs):
+                self.calls.append(("ubend_p2p", kwargs))
+                return "ubend"
+
+            def bend_strt_bend_p2p(self, **kwargs):
+                self.calls.append(("bend_strt_bend_p2p", kwargs))
+                return "bend"
+
+        class FakeInterconnects:
+            Interconnect = FakeInterconnect
+
+        class FakeNazca:
+            interconnects = FakeInterconnects
+
+        original_import = builder._import_mxpic_forge_route
+        original_create = builder._NazcaInterconnectRoute._create_interconnect
+        try:
+            builder._import_mxpic_forge_route = lambda: (_ for _ in ()).throw(ImportError("no forge"))
+            builder._NazcaInterconnectRoute._create_interconnect = staticmethod(
+                lambda **kwargs: FakeInterconnect(**kwargs)
+            )
+
+            route_backend = builder._import_route_backend(FakeNazca)
+            route = route_backend(radius=20, width=0.7, xs="strip", PCB=False)
+
+            self.assertEqual(route.backend_name, "nazca Interconnect")
+            self.assertEqual(route.strt_p2p(pin1="a", pin2="b", arrow=False), "straight")
+            self.assertEqual(route.bend_p2p(pin1="a", pin2="b", radius=10, arrow=False), "bend")
+            self.assertEqual(FakeInterconnect.calls[0][0], "strt_p2p")
+            self.assertEqual(FakeInterconnect.calls[0][1]["width"], 0.7)
+            self.assertEqual(FakeInterconnect.calls[1][0], "bend_strt_bend_p2p")
+            self.assertEqual(FakeInterconnect.calls[1][1]["radius"], 10)
+        finally:
+            builder._import_mxpic_forge_route = original_import
+            builder._NazcaInterconnectRoute._create_interconnect = original_create
+
 
 if __name__ == "__main__":
     unittest.main()