Added a format check for EIGENVAL to vaspio.py

Added a check to 'vaspio.py' testing that the number of columns
implies that the Fermi weights are present in EIGENVAL. This check ensures
that the new format (starting from VASP 5.4) of the file is used.

Corresponding test is added to the suite.

python/vasp/test/_vaspio/EIGENVAL.wrong

@@ -0,0 +1,50 @@
+    1    1    1    1
+  0.1333597E+02  0.2587511E-09  0.2587511E-09  0.2587511E-09  0.5000000E-15
+  1.000000000000000E-004
+  CAR 
+ V                                       
+   11    4    9
+ 
+  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.3703704E-01
+   1      -31.099965
+   2      -31.099965
+   3      -31.099965
+   4       -0.813470
+   5        5.974027
+   6        5.974027
+   7        5.974027
+   8        7.986328
+   9        7.986328
+ 
+  0.3333333E+00  0.0000000E+00  0.0000000E+00  0.4444444E+00
+   1      -31.819277
+   2      -31.322999
+   3      -31.105684
+   4        2.193081
+   5        4.784864
+   6        5.839340
+   7        7.833446
+   8        8.202781
+   9        8.589551
+ 
+  0.3333333E+00  0.3333333E+00  0.0000000E+00  0.2962963E+00
+   1      -31.750021
+   2      -31.750021
+   3      -31.217560
+   4        3.978315
+   5        4.708263
+   6        4.708263
+   7        8.262522
+   8        8.262522
+   9       14.771374
+ 
+ -0.3333333E+00  0.3333333E+00  0.3333333E+00  0.2222222E+00
+   1      -31.719893
+   2      -31.577292
+   3      -31.577292
+   4        3.383714
+   5        3.756320
+   6        7.355029
+   7        7.355029
+   8        8.411511
+   9       11.054129

python/vasp/test/_vaspio/test_eigenval.py

@@ -22,6 +22,7 @@ class TestEigenval(mytest.MyTestCase):
 
     Scenarios:
     - correct EIGENVAL file
+    - wrong EIGENVAL file from old versions of VASP
 
     """
 # Scenario 1
@@ -48,3 +49,12 @@ class TestEigenval(mytest.MyTestCase):
         expected = _rpath + 'EIGENVAL.example.out'
         self.assertFileEqual(testout, expected)
 
+# Scenario 2
+    def test_bad_example(self):
+        filename = 'EIGENVAL.wrong'
+        eigenval = Eigenval()
+
+        err_mess = "EIGENVAL file is incorrect"
+        with self.assertRaisesRegexp(AssertionError, err_mess):
+            eigenval.from_file(vasp_dir=_rpath, eig_filename=filename)
+

python/vasp/vaspio.py

@@ -445,6 +445,7 @@ class Eigenval:
             for ib in xrange(self.nband):
                 sline = f.next().split()
                 tmp = map(float, sline)
+                assert len(tmp) == 2 * self.ispin + 1, "EIGENVAL file is incorrect (probably from old versions of VASP)"
                 self.eigs[ik, ib, :] = tmp[1:self.ispin+1]
                 self.ferw[ik, ib, :] = tmp[self.ispin+1:]