--- a
+++ b/tests/data/pdb/1idg_connectivity.pdb
@@ -0,0 +1,73 @@
+HEADER    1IDG_PROTEIN
+COMPND    1IDG_PROTEIN
+REMARK    GENERATED BY X-TOOL on Wed Nov 21 12:12:23 2012
+ATOM      1  N   PRO A  18      -1.273  20.440   2.471  1.00  0.00           N
+ATOM      2  CA  PRO A  18      -0.824  21.855   2.672  1.00  0.00           C
+ATOM      3  HA  PRO A  18      -1.498  22.596   2.242  1.00  0.00           H
+ATOM      4  C   PRO A  18       0.487  22.213   1.905  1.00  0.00           C
+ATOM      5  O   PRO A  18       0.419  22.841   0.842  1.00  0.00           O
+ATOM      6  CB  PRO A  18      -0.762  21.975   4.213  1.00  0.00           C
+ATOM      7  HB1 PRO A  18       0.029  22.661   4.516  1.00  0.00           H
+ATOM      8  HB2 PRO A  18      -1.715  22.322   4.613  1.00  0.00           H
+ATOM      9  CG  PRO A  18      -0.459  20.553   4.689  1.00  0.00           C
+ATOM     10  HG1 PRO A  18       0.606  20.335   4.612  1.00  0.00           H
+ATOM     11  HG2 PRO A  18      -0.784  20.409   5.719  1.00  0.00           H
+ATOM     12  CD  PRO A  18      -1.268  19.674   3.732  1.00  0.00           C
+ATOM     13  HD1 PRO A  18      -2.283  19.528   4.102  1.00  0.00           H
+ATOM     14  HD2 PRO A  18      -0.789  18.704   3.596  1.00  0.00           H
+ATOM     15  N   GLY A  19       1.639  21.709   2.369  1.00  0.00           N
+ATOM     16  H   GLY A  19       1.875  21.815   3.376  1.00  0.00           H
+ATOM     17  CA  GLY A  19       2.576  21.008   1.476  1.00  0.00           C
+ATOM     18  HA1 GLY A  19       2.447  21.391   0.464  1.00  0.00           H
+ATOM     19  HA2 GLY A  19       3.594  21.207   1.811  1.00  0.00           H
+ATOM     20  C   GLY A  19       2.347  19.459   1.460  1.00  0.00           C
+ATOM     21  O   GLY A  19       1.397  18.910   2.030  1.00  0.00           O
+ATOM     22  N   GLU A  20       3.206  18.683   0.792  1.00  0.00           N
+ATOM     23  H   GLU A  20       2.845  17.758   0.483  1.00  0.00           H
+ATOM     24  CA  GLU A  20       4.528  18.968   0.462  1.00  0.00           C
+ATOM     25  HA  GLU A  20       5.115  19.678  -0.120  1.00  0.00           H
+ATOM     26  C   GLU A  20       3.579  17.608   0.227  1.00  0.00           C
+ATOM     27  O   GLU A  20       3.552  16.620   0.969  1.00  0.00           O
+ATOM     28  CB  GLU A  20       5.562  18.956   1.610  1.00  0.00           C
+ATOM     29  HB1 GLU A  20       5.272  19.699   2.353  1.00  0.00           H
+ATOM     30  HB2 GLU A  20       5.566  17.968   2.070  1.00  0.00           H
+ATOM     31  CG  GLU A  20       6.983  19.279   1.110  1.00  0.00           C
+ATOM     32  HG1 GLU A  20       7.699  18.724   1.717  1.00  0.00           H
+ATOM     33  HG2 GLU A  20       7.066  18.961   0.071  1.00  0.00           H
+ATOM     34  CD  GLU A  20       7.327  20.772   1.192  1.00  0.00           C
+ATOM     35  OE1 GLU A  20       6.844  21.547   0.337  1.00  0.00           O
+ATOM     36  OE2 GLU A  20       8.052  21.178   2.127  1.00  0.00           O
+ATOM     37  N   ASN A  21       3.718  17.477  -1.104  1.00  0.00           N
+ATOM     38  H   ASN A  21       3.332  18.225  -1.716  1.00  0.00           H
+ATOM     39  CA  ASN A  21       4.396  16.316  -1.749  1.00  0.00           C
+ATOM     40  HA  ASN A  21       4.528  16.531  -2.809  1.00  0.00           H
+ATOM     41  C   ASN A  21       3.511  15.049  -1.941  1.00  0.00           C
+ATOM     42  O   ASN A  21       2.438  15.138  -2.546  1.00  0.00           O
+ATOM     43  CB  ASN A  21       5.894  16.172  -1.254  1.00  0.00           C
+ATOM     44  HB1 ASN A  21       5.967  16.626  -0.266  1.00  0.00           H
+ATOM     45  HB2 ASN A  21       6.124  15.109  -1.182  1.00  0.00           H
+ATOM     46  CG  ASN A  21       6.959  16.830  -2.161  1.00  0.00           C
+ATOM     47  OD1 ASN A  21       6.765  17.894  -2.746  1.00  0.00           O
+ATOM     48  ND2 ASN A  21       8.143  16.251  -2.257  1.00  0.00           N
+ATOM     49 1HD2 ASN A  21       8.895  16.695  -2.821  1.00  0.00           H
+ATOM     50 2HD2 ASN A  21       8.323  15.351  -1.768  1.00  0.00           H
+ATOM     51  N   LEU A  22       4.015  13.855  -1.587  1.00  0.00           N
+ATOM     52  H   LEU A  22       4.508  13.765  -0.676  1.00  0.00           H
+ATOM     53  CA  LEU A  22       3.888  12.655  -2.462  1.00  0.00           C
+ATOM     54  HA  LEU A  22       3.275  12.917  -3.325  1.00  0.00           H
+ATOM     55  C   LEU A  22       3.218  11.518  -1.650  1.00  0.00           C
+ATOM     56  O   LEU A  22       3.395  11.424  -0.429  1.00  0.00           O
+ATOM     57  CB  LEU A  22       5.276  12.183  -3.015  1.00  0.00           C
+ATOM     58  HB1 LEU A  22       5.774  11.653  -2.203  1.00  0.00           H
+ATOM     59  HB2 LEU A  22       5.071  11.488  -3.829  1.00  0.00           H
+ATOM     60  CG  LEU A  22       6.300  13.234  -3.565  1.00  0.00           C
+ATOM     61  HG  LEU A  22       6.512  13.883  -2.715  1.00  0.00           H
+ATOM     62  CD1 LEU A  22       7.626  12.581  -4.003  1.00  0.00           C
+ATOM     63 1HD1 LEU A  22       8.081  12.078  -3.150  1.00  0.00           H
+ATOM     64 2HD1 LEU A  22       7.429  11.855  -4.791  1.00  0.00           H
+ATOM     65 3HD1 LEU A  22       8.302  13.350  -4.376  1.00  0.00           H
+ATOM     66  CD2 LEU A  22       5.734  14.172  -4.657  1.00  0.00           C
+ATOM     67 1HD2 LEU A  22       5.401  13.578  -5.508  1.00  0.00           H
+ATOM     68 2HD2 LEU A  22       4.891  14.732  -4.252  1.00  0.00           H
+ATOM     69 3HD2 LEU A  22       6.512  14.865  -4.978  1.00  0.00           H
+END