diff --git a/src/autorouter/board.rs b/src/autorouter/board.rs
index 0ef014d..b4aacef 100644
--- a/src/autorouter/board.rs
+++ b/src/autorouter/board.rs
@@ -183,7 +183,7 @@ impl<R: RulesTrait> Board<R> {
         self.net_to_netname.get(&net)
     }
 
-    pub fn band_between_pins(&self, pinname1: &String, pinname2: &String) -> Option<BandIndex> {
+    pub fn band_between_pins(&self, pinname1: &str, pinname2: &str) -> Option<BandIndex> {
         if let Some(band) = self
             .pinname_pair_to_band
             .get(&(pinname1.to_string(), pinname2.to_string()))
diff --git a/tests/four_3rd_order_smd_lc_filters.rs b/tests/four_3rd_order_smd_lc_filters.rs
index 2df0451..99e4b46 100644
--- a/tests/four_3rd_order_smd_lc_filters.rs
+++ b/tests/four_3rd_order_smd_lc_filters.rs
@@ -12,6 +12,8 @@ use topola::{
     triangulation::GetTrianvertexIndex,
 };
 
+mod common;
+
 #[test]
 fn test() {
     let design = DsnDesign::load_from_file(
@@ -26,65 +28,5 @@ fn test() {
 
     let (mut autorouter, ..) = invoker.destruct();
 
-    for ratline in autorouter.ratsnest().graph().edge_indices() {
-        // Accessing endpoints may create new dots because apex construction is lazy, so we access
-        // tem all before starting unionfind, as it requires a constant index bound.
-        let _ = autorouter.ratline_endpoints(ratline);
-    }
-
-    let mut unionfind = UnionFind::new(
-        autorouter
-            .board()
-            .layout()
-            .drawing()
-            .geometry()
-            .graph()
-            .node_bound(),
-    );
-
-    for primitive in autorouter.board().layout().drawing().primitive_nodes() {
-        dbg!(primitive);
-        for joined in autorouter
-            .board()
-            .layout()
-            .drawing()
-            .geometry()
-            .joineds(primitive)
-        {
-            dbg!(joined);
-            unionfind.union(primitive.node_index(), joined.node_index());
-        }
-    }
-
-    for ratline in autorouter.ratsnest().graph().edge_indices() {
-        let (source_dot, target_dot) = autorouter.ratline_endpoints(ratline);
-        let source_net = autorouter
-            .board()
-            .layout()
-            .drawing()
-            .primitive(source_dot)
-            .maybe_net();
-        let target_net = autorouter
-            .board()
-            .layout()
-            .drawing()
-            .primitive(target_dot)
-            .maybe_net();
-
-        assert_eq!(source_net, target_net);
-        let net = source_net.unwrap();
-
-        if let Some(netname) = autorouter.board().netname(net) {
-            dbg!(netname);
-
-            // We don't route GND.
-            if netname != "GND" {
-                dbg!(source_dot, target_dot);
-                assert_eq!(
-                    unionfind.find(source_dot.node_index()),
-                    unionfind.find(target_dot.node_index())
-                );
-            }
-        }
-    }
+    common::assert_single_layer_groundless_autoroute(&mut autorouter, "F.Cu");
 }
diff --git a/tests/single_layer_tht_diode_bridge_rectifier.rs b/tests/single_layer_tht_diode_bridge_rectifier.rs
index 4b6c94b..bfc14ba 100644
--- a/tests/single_layer_tht_diode_bridge_rectifier.rs
+++ b/tests/single_layer_tht_diode_bridge_rectifier.rs
@@ -16,6 +16,8 @@ use topola::{
     triangulation::GetTrianvertexIndex,
 };
 
+mod common;
+
 #[test]
 fn test() {
     let design = DsnDesign::load_from_file(
@@ -30,103 +32,6 @@ fn test() {
 
     let (mut autorouter, ..) = invoker.destruct();
 
-    for ratline in autorouter.ratsnest().graph().edge_indices() {
-        // Accessing endpoints may create new dots because apex construction is lazy, so we access
-        // tem all before starting unionfind, as it requires a constant index bound.
-        let _ = autorouter.ratline_endpoints(ratline);
-    }
-
-    let mut unionfind = UnionFind::new(
-        autorouter
-            .board()
-            .layout()
-            .drawing()
-            .geometry()
-            .graph()
-            .node_bound(),
-    );
-
-    for primitive in autorouter.board().layout().drawing().primitive_nodes() {
-        dbg!(primitive);
-        for joined in autorouter
-            .board()
-            .layout()
-            .drawing()
-            .geometry()
-            .joineds(primitive)
-        {
-            dbg!(joined);
-            unionfind.union(primitive.node_index(), joined.node_index());
-        }
-    }
-
-    for ratline in autorouter.ratsnest().graph().edge_indices() {
-        let (source_dot, target_dot) = autorouter.ratline_endpoints(ratline);
-
-        let source_layer = autorouter
-            .board()
-            .layout()
-            .drawing()
-            .primitive(source_dot)
-            .layer();
-        let target_layer = autorouter
-            .board()
-            .layout()
-            .drawing()
-            .primitive(target_dot)
-            .layer();
-
-        let Some(source_layername) = autorouter.board().layername(source_layer) else {
-            continue;
-        };
-
-        let Some(target_layername) = autorouter.board().layername(target_layer) else {
-            continue;
-        };
-
-        if source_layername != "F.Cu" || target_layername != "F.Cu" {
-            continue;
-        }
-
-        let source_net = autorouter
-            .board()
-            .layout()
-            .drawing()
-            .primitive(source_dot)
-            .maybe_net();
-        let target_net = autorouter
-            .board()
-            .layout()
-            .drawing()
-            .primitive(target_dot)
-            .maybe_net();
-
-        assert_eq!(source_net, target_net);
-        let net = source_net.unwrap();
-
-        if let Some(netname) = autorouter.board().netname(net) {
-            dbg!(netname);
-            dbg!(source_dot, target_dot);
-            assert_eq!(
-                unionfind.find(source_dot.node_index()),
-                unionfind.find(target_dot.node_index())
-            );
-        }
-
-        let source_pinname = autorouter
-            .board()
-            .node_pinname(NodeIndex::Primitive(source_dot.into()))
-            .unwrap();
-        let target_pinname = autorouter
-            .board()
-            .node_pinname(NodeIndex::Primitive(target_dot.into()))
-            .unwrap();
-        dbg!(source_pinname, target_pinname);
-
-        let band = autorouter
-            .board()
-            .band_between_pins(source_pinname, target_pinname)
-            .unwrap();
-        dbg!(autorouter.board().layout().band_length(band));
-    }
+    common::assert_single_layer_groundless_autoroute(&mut autorouter, "F.Cu");
+    common::assert_band_length(autorouter.board(), "J2-2", "D4-2", 15511.0, 0.5);
 }