diff --git a/src/db/unit_tests/dbDeepEdgesTests.cc b/src/db/unit_tests/dbDeepEdgesTests.cc
index 3dc27c43c..7d992997e 100644
--- a/src/db/unit_tests/dbDeepEdgesTests.cc
+++ b/src/db/unit_tests/dbDeepEdgesTests.cc
@@ -1454,55 +1454,55 @@ TEST(22_InteractingWithCount)
 
   db::Edges edup;
 
-  EXPECT_EQ (e.selected_interacting (e2).to_string (), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (e2, size_t (2)).to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (e2, size_t (2), size_t(2)).to_string (), "(0,10;200,10)");
-  EXPECT_EQ (e.selected_interacting (e2, size_t (2), size_t(3)).to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (e2, size_t (3)).to_string (), "(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (e2, size_t (4)).to_string (), "");
+  EXPECT_EQ (db::compare (e.selected_interacting (e2), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (e2, size_t (2)), "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (e2, size_t (2), size_t(2)), "(0,10;200,10)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (e2, size_t (2), size_t(3)), "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (e2, size_t (3)), "(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (e2, size_t (4)), ""), true);
 
   edup = e;
   edup.select_interacting (e2, size_t (2), size_t(3));
-  EXPECT_EQ (edup.to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
+  EXPECT_EQ (db::compare (edup, "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
 
-  EXPECT_EQ (e.selected_not_interacting (e2).to_string (), "");
-  EXPECT_EQ (e.selected_not_interacting (e2, size_t (2)).to_string (), "(0,0;200,0)");
-  EXPECT_EQ (e.selected_not_interacting (e2, size_t (2), size_t(2)).to_string (), "(0,0;200,0);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_not_interacting (e2, size_t (2), size_t(3)).to_string (), "(0,0;200,0)");
-  EXPECT_EQ (e.selected_not_interacting (e2, size_t (3)).to_string (), "(0,0;200,0);(0,10;200,10)");
-  EXPECT_EQ (e.selected_not_interacting (e2, size_t (4)).to_string (), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)");
+  EXPECT_EQ (db::compare (e.selected_not_interacting (e2), ""), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (e2, size_t (2)), "(0,0;200,0)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (e2, size_t (2), size_t(2)), "(0,0;200,0);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (e2, size_t (2), size_t(3)), "(0,0;200,0)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (e2, size_t (3)), "(0,0;200,0);(0,10;200,10)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (e2, size_t (4)), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
 
   edup = e;
   edup.select_not_interacting (e2, size_t (2), size_t(3));
-  EXPECT_EQ (edup.to_string (), "(0,0;200,0)");
+  EXPECT_EQ (db::compare (edup, "(0,0;200,0)"), true);
 
-  EXPECT_EQ (e.selected_interacting_differential (e2, size_t (2), size_t(3)).first.to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting_differential (e2, size_t (2), size_t(3)).second.to_string (), "(0,0;200,0)");
+  EXPECT_EQ (db::compare (e.selected_interacting_differential (e2, size_t (2), size_t(3)).first, "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting_differential (e2, size_t (2), size_t(3)).second, "(0,0;200,0)"), true);
 
-  EXPECT_EQ (e.selected_interacting (r2).to_string (), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (r2, size_t (2)).to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (r2, size_t (2), size_t(2)).to_string (), "(0,10;200,10)");
-  EXPECT_EQ (e.selected_interacting (r2, size_t (2), size_t(3)).to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (r2, size_t (3)).to_string (), "(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting (r2, size_t (4)).to_string (), "");
+  EXPECT_EQ (db::compare (e.selected_interacting (r2), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (r2, size_t (2)), "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (r2, size_t (2), size_t(2)), "(0,10;200,10)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (r2, size_t (2), size_t(3)), "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (r2, size_t (3)), "(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting (r2, size_t (4)), ""), true);
 
   edup = e;
   edup.select_interacting (r2, size_t (2), size_t(3));
-  EXPECT_EQ (edup.to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
+  EXPECT_EQ (db::compare (edup, "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
 
-  EXPECT_EQ (e.selected_not_interacting (r2).to_string (), "");
-  EXPECT_EQ (e.selected_not_interacting (r2, size_t (2)).to_string (), "(0,0;200,0)");
-  EXPECT_EQ (e.selected_not_interacting (r2, size_t (2), size_t(2)).to_string (), "(0,0;200,0);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_not_interacting (r2, size_t (2), size_t(3)).to_string (), "(0,0;200,0)");
-  EXPECT_EQ (e.selected_not_interacting (r2, size_t (3)).to_string (), "(0,0;200,0);(0,10;200,10)");
-  EXPECT_EQ (e.selected_not_interacting (r2, size_t (4)).to_string (), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)");
+  EXPECT_EQ (db::compare (e.selected_not_interacting (r2), ""), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (r2, size_t (2)), "(0,0;200,0)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (r2, size_t (2), size_t(2)), "(0,0;200,0);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (r2, size_t (2), size_t(3)), "(0,0;200,0)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (r2, size_t (3)), "(0,0;200,0);(0,10;200,10)"), true);
+  EXPECT_EQ (db::compare (e.selected_not_interacting (r2, size_t (4)), "(0,0;200,0);(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
 
   edup = e;
   edup.select_not_interacting (r2, size_t (2), size_t(3));
-  EXPECT_EQ (edup.to_string (), "(0,0;200,0)");
+  EXPECT_EQ (db::compare (edup, "(0,0;200,0)"), true);
 
-  EXPECT_EQ (e.selected_interacting_differential (r2, size_t (2), size_t(3)).first.to_string (), "(0,10;200,10);(0,20;200,20);(0,30;200,30)");
-  EXPECT_EQ (e.selected_interacting_differential (r2, size_t (2), size_t(3)).second.to_string (), "(0,0;200,0)");
+  EXPECT_EQ (db::compare (e.selected_interacting_differential (r2, size_t (2), size_t(3)).first, "(0,10;200,10);(0,20;200,20);(0,30;200,30)"), true);
+  EXPECT_EQ (db::compare (e.selected_interacting_differential (r2, size_t (2), size_t(3)).second, "(0,0;200,0)"), true);
 }
 
 
diff --git a/src/db/unit_tests/dbEdgesTests.cc b/src/db/unit_tests/dbEdgesTests.cc
index 727405280..97f0d890c 100644
--- a/src/db/unit_tests/dbEdgesTests.cc
+++ b/src/db/unit_tests/dbEdgesTests.cc
@@ -789,27 +789,27 @@ TEST(20)
     EXPECT_EQ (r2.has_valid_edges (), false);
     db::Region rr1 (db::RecursiveShapeIterator (ly, ly.cell (top), lp1), db::ICplxTrans (), false);
     EXPECT_EQ (rr1.has_valid_polygons (), false);
-    EXPECT_EQ ((r1 & r2).to_string (100), "(80,70;80,40)");
-    EXPECT_EQ ((r1 + r2).to_string (100), "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(50,70;80,70);(80,70;80,40);(80,40;50,40);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(80,40;80,70);(80,70;110,70);(110,70;110,40);(110,40;80,40);(110,40;110,70);(110,70;140,70);(140,70;140,40);(140,40;110,40)");
-    EXPECT_EQ ((r1 + r2).merged ().to_string (100), "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(50,70;140,70);(140,70;140,40);(140,40;50,40)");
-    EXPECT_EQ ((r1 | r2).to_string (100), "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(50,70;140,70);(140,70;140,40);(140,40;50,40)");
-    EXPECT_EQ ((r1 ^ r2).to_string (100), "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(50,70;140,70);(140,70;140,40);(140,40;50,40)");
-    EXPECT_EQ ((r1 ^ r1).to_string (100), "");
-    EXPECT_EQ ((r1 - r2).to_string (100), "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(50,70;80,70);(80,40;50,40)");
-    EXPECT_EQ ((r1 - r1).to_string (100), "");
-    EXPECT_EQ (r2.merged ().to_string (100), "(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(80,40;80,70);(80,70;140,70);(140,70;140,40);(140,40;80,40)");
-    EXPECT_EQ (rr1.to_string (100), "(0,0;0,30;30,30;30,0);(50,0;50,30;80,30;80,0);(50,40;50,70;80,70;80,40)");
-    EXPECT_EQ (r2.selected_interacting (rr1).to_string (100), "(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(40,10;10,10);(80,40;80,70);(80,70;140,70);(140,40;80,40)");
-    EXPECT_EQ (r2.selected_interacting_differential (rr1).first.to_string (100), "(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(40,10;10,10);(80,40;80,70);(80,70;140,70);(140,40;80,40)");
-    EXPECT_EQ (r2.selected_not_interacting (rr1).to_string (100), "(10,40;40,40);(40,40;40,10);(140,70;140,40)");
-    EXPECT_EQ (r2.selected_interacting_differential (rr1).second.to_string (100), "(10,40;40,40);(40,40;40,10);(140,70;140,40)");
+    EXPECT_EQ (db::compare (r1 & r2, "(80,70;80,40)"), true);
+    EXPECT_EQ (db::compare (r1 + r2, "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(50,70;80,70);(80,70;80,40);(80,40;50,40);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(80,40;80,70);(80,70;110,70);(110,70;110,40);(110,40;80,40);(110,40;110,70);(110,70;140,70);(140,70;140,40);(140,40;110,40)"), true);
+    EXPECT_EQ (db::compare ((r1 + r2).merged (), "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(50,70;140,70);(140,70;140,40);(140,40;50,40)"), true);
+    EXPECT_EQ (db::compare (r1 | r2, "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(50,70;140,70);(140,70;140,40);(140,40;50,40)"), true);
+    EXPECT_EQ (db::compare (r1 ^ r2, "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(50,70;140,70);(140,70;140,40);(140,40;50,40)"), true);
+    EXPECT_EQ (db::compare (r1 ^ r1, ""), true);
+    EXPECT_EQ (db::compare (r1 - r2, "(0,0;0,30);(0,30;30,30);(30,30;30,0);(30,0;0,0);(50,0;50,30);(50,30;80,30);(80,30;80,0);(80,0;50,0);(50,40;50,70);(50,70;80,70);(80,40;50,40)"), true);
+    EXPECT_EQ (db::compare (r1 - r1, ""), true);
+    EXPECT_EQ (db::compare (r2.merged (), "(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(10,40;40,40);(40,40;40,10);(40,10;10,10);(80,40;80,70);(80,70;140,70);(140,70;140,40);(140,40;80,40)"), true);
+    EXPECT_EQ (db::compare (rr1, "(0,0;0,30;30,30;30,0);(50,0;50,30;80,30;80,0);(50,40;50,70;80,70;80,40)"), true);
+    EXPECT_EQ (db::compare (r2.selected_interacting (rr1), "(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(40,10;10,10);(80,40;80,70);(80,70;140,70);(140,40;80,40)"), true);
+    EXPECT_EQ (db::compare (r2.selected_interacting_differential (rr1).first, "(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(40,10;10,10);(80,40;80,70);(80,70;140,70);(140,40;80,40)"), true);
+    EXPECT_EQ (db::compare (r2.selected_not_interacting (rr1), "(10,40;40,40);(40,40;40,10);(140,70;140,40)"), true);
+    EXPECT_EQ (db::compare (r2.selected_interacting_differential (rr1).second, "(10,40;40,40);(40,40;40,10);(140,70;140,40)"), true);
 
     db::Edges r2dup = r2;
     r2.select_interacting (rr1);
     EXPECT_EQ (db::compare (r2, "(60,10;60,20);(60,20;70,20);(70,20;70,10);(70,10;60,10);(10,10;10,40);(40,10;10,10);(80,40;80,70);(80,70;140,70);(140,40;80,40)"), true);
     r2 = r2dup;
     r2.select_not_interacting (rr1);
-    EXPECT_EQ (r2.to_string (100), "(10,40;40,40);(40,40;40,10);(140,70;140,40)");
+    EXPECT_EQ (db::compare (r2, "(10,40;40,40);(40,40;40,10);(140,70;140,40)"), true);
 
     r2 = db::Edges (db::RecursiveShapeIterator (ly, ly.cell (top), l2), false);
     EXPECT_EQ (r2.has_valid_edges (), false);