// before using the string class, must create a string context per thread,
   // it contains cached amd shared data:
   const alloc = std.testing.allocator;
   try Ctring.Init(alloc);
   defer Ctring.Deinit();

   {
       var top = try Ctring.New("🧑‍🌾 橋 5b");
       defer top.deinit();

       {
           var v = top.view(0, 3);
           try expect(v.eqUtf8("🧑‍🌾 橋"));
           v.setView(4, 6);
           try expect(v.eqAscii("5b"));

           v.setView(0, 6);
           try expect(v.startsWith(top));
           try expect(v.startsWithUtf8("🧑‍🌾 橋"));
       }

       { // iterate over graphemes forward
           const correct = [_][]const u8 {"🧑‍🌾", " ", "橋", " ", "5", "b"};
           var iter = top.iterator(0);
           var idx: usize = 0;
           while (iter.next()) |gr| {
               try expect(gr.eqUtf8(correct[idx]));
               idx += 1;
           }
       }

       { // iterate over graphemes backwards
           const correct = [_][]const u8 {"b", "5", " ", "橋", " ", "🧑‍🌾"};
           var iter = top.iterator(top.last());
           var idx: usize = 0;
           while (iter.prev()) |gr| {
               try expect(gr.eqUtf8(correct[idx]));
               idx += 1;
           }
       }
   }

   {
       var top = try Ctring.New("🧑‍🌾 .橋 .5b.橋");
       defer top.deinit();
       const v = top.view(0, top.size());
       try expect(v.findAscii(".", null) == 2);
       try expect(v.findAscii(".", 3) == 5);
       try expect(v.findUtf8("橋", null) == 3);
       try expect(v.findUtf8(".橋", null) == 2);
       try expect(v.findUtf8("橋", 4) == 9);
       try expect(v.findUtf8(".橋", 3) == 8);
   }

   { // splitting
       var root = try Ctring.New("Hello,  world! Again!");
       defer root.deinit();
       const rootv = root.view(0, root.size());
       {
           var arr = try rootv.splitAscii(" ", true);
           defer arr.deinit(ctx.a);

           const correct = [_][]const u8{"Hello,", "", "world!", "Again!"};
           for (arr.items, correct) |a, b| {
               // mtl.debug(@src(), "{f} vs \"{s}\"", .{a._(2), b});
               try expect(a.eqAscii(b));
           }
       }
   }