fix: Fix parse record error verbiage

tests/test_parser_record.py

@@ -4,8 +4,10 @@
 
 import io
 import sys
+import pytest
 
 from vcfpy import parser
+from vcfpy import exceptions
 
 __author__ = "Manuel Holtgrewe <[email protected]>"
 
@@ -178,3 +180,16 @@ def test_missing_pass(recwarn):
     RESULT = p.parse_next_record()
     assert str(RESULT) == EXPECTED
     assert list(recwarn) == []
+
+
+def test_parse_line_invalid_number_of_fields():
+    """Test parsing VCF file exception message"""
+    HEADER = "##fileformat=VCFv4.2\n#CHROM\tPOS\tID\tREF\tALT\tQUAL\tFILTER\tINFO\tFORMAT\n"
+    LINES = "20\t1\t.\tC\tG\t.\tPASS\t.\tGT\n"
+    EXPECTED = "The line contains an invalid number of fields. Was 9 but expected 8"
+    p = parser.Parser(io.StringIO(HEADER + LINES), "<builtin>")
+    p.parse_header()
+    with pytest.raises(exceptions.InvalidRecordException) as record_error:
+        p.parse_next_record()
+
+    assert EXPECTED in str(record_error.value)

vcfpy/parser.py

@@ -514,7 +514,7 @@ def _split_line(self, line_str):
             raise exceptions.InvalidRecordException(
                 (
                     "The line contains an invalid number of fields. Was "
-                    "{} but expected {}\n{}".format(len(arr), 9 + len(self.samples.names), line_str)
+                    "{} but expected {}\n{}".format(len(arr), self.expected_fields, line_str)
                 )
             )
         return arr