make ClustalW unit test independent of sequence order

Andrius Merkys reported architecture dependent behaviour regarding
ordering of aligned sequences. We want to keep the order as given
by the used ClustalW executable which is potentially different as
in the unit test reference file.

modules/bindings/tests/test_clustalw.py

@@ -42,8 +42,16 @@ class TestClustalWBindings(unittest.TestCase):
     
   def testMultipleClustalW(self):
     aln=clustalw.ClustalW(self.multseq)
-    assert self.mult_alignment.ToString(80) == aln.ToString(80), \
-           "Multiple alignment differs from precomputed one"
+    # order of sequences in aln may differ (reported by Andrius Merkys who
+    # found architecture dependent behaviour)
+    # We therefore check for matching sequence names and respective sequences
+    # but not for order.
+    ref_sequences = {s.GetName(): str(s) for s in self.mult_alignment.sequences}
+    sequences = {s.GetName(): str(s) for s in aln.sequences}
+    self.assertEqual(sorted(ref_sequences.keys()), sorted(sequences.keys()))
+    for sname, s in ref_sequences.items():
+      self.assertEqual(s, sequences[sname])
+
 
   def testStringClustalW(self):
     aln=clustalw.ClustalW(self.strseq1, self.strseq2)