tests-pure: fixing test-parseindex2

This is a followup to D7603 (49fa0b31ee1d) which broke
the tests for pure Python implementation. There are two
divergences between pure and C implementations:

- the pure implementation would accept only -1 as slice end,
  whereas C accepts both -1 and len(index)
- in pure Python, `headrevs` is provided by revlog.py, not
  by the index.

Differential Revision: https://phab.mercurial-scm.org/D7707

tests/test-parseindex2.py

@@ -1,280 +1,282 b''
 """This unit test primarily tests parsers.parse_index2().
 
 It also checks certain aspects of the parsers module as a whole.
 """
 
 from __future__ import absolute_import, print_function
 
 import struct
 import subprocess
 import sys
 import unittest
 
 from mercurial.node import (
     nullid,
     nullrev,
 )
 from mercurial import (
     node as nodemod,
     policy,
     pycompat,
 )
 
 parsers = policy.importmod('parsers')
 
 # original python implementation
 def gettype(q):
     return int(q & 0xFFFF)
 
 
 def offset_type(offset, type):
     return int(int(offset) << 16 | type)
 
 
 indexformatng = ">Qiiiiii20s12x"
 
 
 def py_parseindex(data, inline):
     s = 64
     cache = None
     index = []
     nodemap = {nullid: nullrev}
     n = off = 0
 
     l = len(data) - s
     append = index.append
     if inline:
         cache = (0, data)
         while off <= l:
             e = struct.unpack(indexformatng, data[off : off + s])
             nodemap[e[7]] = n
             append(e)
             n += 1
             if e[1] < 0:
                 break
             off += e[1] + s
     else:
         while off <= l:
             e = struct.unpack(indexformatng, data[off : off + s])
             nodemap[e[7]] = n
             append(e)
             n += 1
             off += s
 
     e = list(index[0])
     type = gettype(e[0])
     e[0] = offset_type(0, type)
     index[0] = tuple(e)
 
     return index, cache
 
 
 data_inlined = (
     b'\x00\x01\x00\x01\x00\x00\x00\x00\x00\x00\x01\x8c'
     b'\x00\x00\x04\x07\x00\x00\x00\x00\x00\x00\x15\x15\xff\xff\xff'
     b'\xff\xff\xff\xff\xff\xebG\x97\xb7\x1fB\x04\xcf\x13V\x81\tw\x1b'
     b'w\xdduR\xda\xc6\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
     b'x\x9c\x9d\x93?O\xc30\x10\xc5\xf7|\x8a\xdb\x9a\xa8m\x06\xd8*\x95'
     b'\x81B\xa1\xa2\xa2R\xcb\x86Pd\x9a\x0b5$vd_\x04\xfd\xf6\x9c\xff@'
     b'\x11!\x0b\xd9\xec\xf7\xbbw\xe7gG6\xad6\x04\xdaN\xc0\x92\xa0$)'
     b'\xb1\x82\xa2\xd1%\x16\xa4\x8b7\xa9\xca\xd4-\xb2Y\x02\xfc\xc9'
     b'\xcaS\xf9\xaeX\xed\xb6\xd77Q\x02\x83\xd4\x19\xf5--Y\xea\xe1W'
     b'\xab\xed\x10\xceR\x0f_\xdf\xdf\r\xe1,\xf5\xf0\xcb\xf5 \xceR\x0f'
     b'_\xdc\x0e\x0e\xc3R\x0f_\xae\x96\x9b!\x9e\xa5\x1e\xbf\xdb,\x06'
     b'\xc7q\x9a/\x88\x82\xc3B\xea\xb5\xb4TJ\x93\xb6\x82\x0e\xe16\xe6'
     b'KQ\xdb\xaf\xecG\xa3\xd1 \x01\xd3\x0b_^\xe8\xaa\xa0\xae\xad\xd1'
     b'&\xbef\x1bz\x08\xb0|\xc9Xz\x06\xf6Z\x91\x90J\xaa\x17\x90\xaa'
     b'\xd2\xa6\x11$5C\xcf\xba#\xa0\x03\x02*2\x92-\xfc\xb1\x94\xdf\xe2'
     b'\xae\xb8\'m\x8ey0^\x85\xd3\x82\xb4\xf0`:\x9c\x00\x8a\xfd\x01'
     b'\xb0\xc6\x86\x8b\xdd\xae\x80\xf3\xa9\x9fd\x16\n\x00R%\x1a\x06'
     b'\xe9\xd8b\x98\x1d\xf4\xf3+\x9bf\x01\xd8p\x1b\xf3.\xed\x9f^g\xc3'
     b'^\xd9W81T\xdb\xd5\x04sx|\xf2\xeb\xd6`%?x\xed"\x831\xbf\xf3\xdc'
     b'b\xeb%gaY\xe1\xad\x9f\xb9f\'1w\xa9\xa5a\x83s\x82J\xb98\xbc4\x8b'
     b'\x83\x00\x9f$z\xb8#\xa5\xb1\xdf\x98\xd9\xec\x1b\x89O\xe3Ts\x9a4'
     b'\x17m\x8b\xfc\x8f\xa5\x95\x9a\xfc\xfa\xed,\xe5|\xa1\xfe\x15\xb9'
     b'\xbc\xb2\x93\x1f\xf2\x95\xff\xdf,\x1a\xc5\xe7\x17*\x93Oz:>\x0e'
 )
 
 data_non_inlined = (
     b'\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01D\x19'
     b'\x00\x07e\x12\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff'
     b'\xff\xff\xff\xff\xd1\xf4\xbb\xb0\xbe\xfc\x13\xbd\x8c\xd3\x9d'
     b'\x0f\xcd\xd9;\x8c\x07\x8cJ/\x00\x00\x00\x00\x00\x00\x00\x00\x00'
     b'\x00\x00\x00\x00\x00\x00\x01D\x19\x00\x00\x00\x00\x00\xdf\x00'
     b'\x00\x01q\x00\x00\x00\x01\x00\x00\x00\x01\x00\x00\x00\x00\xff'
     b'\xff\xff\xff\xc1\x12\xb9\x04\x96\xa4Z1t\x91\xdfsJ\x90\xf0\x9bh'
     b'\x07l&\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
     b'\x00\x01D\xf8\x00\x00\x00\x00\x01\x1b\x00\x00\x01\xb8\x00\x00'
     b'\x00\x01\x00\x00\x00\x02\x00\x00\x00\x01\xff\xff\xff\xff\x02\n'
     b'\x0e\xc6&\xa1\x92\xae6\x0b\x02i\xfe-\xe5\xbao\x05\xd1\xe7\x00'
     b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01F'
     b'\x13\x00\x00\x00\x00\x01\xec\x00\x00\x03\x06\x00\x00\x00\x01'
     b'\x00\x00\x00\x03\x00\x00\x00\x02\xff\xff\xff\xff\x12\xcb\xeby1'
     b'\xb6\r\x98B\xcb\x07\xbd`\x8f\x92\xd9\xc4\x84\xbdK\x00\x00\x00'
     b'\x00\x00\x00\x00\x00\x00\x00\x00\x00'
 )
 
 
 def parse_index2(data, inline):
     index, chunkcache = parsers.parse_index2(data, inline)
     return list(index), chunkcache
 
 
 def importparsers(hexversion):
     """Import mercurial.parsers with the given sys.hexversion."""
     # The file parsers.c inspects sys.hexversion to determine the version
     # of the currently-running Python interpreter, so we monkey-patch
     # sys.hexversion to simulate using different versions.
     code = (
         "import sys; sys.hexversion=%s; "
         "import mercurial.cext.parsers" % hexversion
     )
     cmd = "python -c \"%s\"" % code
     # We need to do these tests inside a subprocess because parser.c's
     # version-checking code happens inside the module init function, and
     # when using reload() to reimport an extension module, "The init function
     # of extension modules is not called a second time"
     # (from http://docs.python.org/2/library/functions.html?#reload).
     p = subprocess.Popen(
         cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT
     )
     return p.communicate()  # returns stdout, stderr
 
 
 def hexfailmsg(testnumber, hexversion, stdout, expected):
     try:
         hexstring = hex(hexversion)
     except TypeError:
         hexstring = None
     return (
         "FAILED: version test #%s with Python %s and patched "
         "sys.hexversion %r (%r):\n Expected %s but got:\n-->'%s'\n"
         % (
             testnumber,
             sys.version_info,
             hexversion,
             hexstring,
             expected,
             stdout,
         )
     )
 
 
 def makehex(major, minor, micro):
     return int("%x%02x%02x00" % (major, minor, micro), 16)
 
 
 class parseindex2tests(unittest.TestCase):
     def assertversionokay(self, testnumber, hexversion):
         stdout, stderr = importparsers(hexversion)
         self.assertFalse(
             stdout, hexfailmsg(testnumber, hexversion, stdout, 'no stdout')
         )
 
     def assertversionfail(self, testnumber, hexversion):
         stdout, stderr = importparsers(hexversion)
         # We include versionerrortext to distinguish from other ImportErrors.
         errtext = b"ImportError: %s" % pycompat.sysbytes(
             parsers.versionerrortext
         )
         self.assertIn(
             errtext,
             stdout,
             hexfailmsg(
                 testnumber,
                 hexversion,
                 stdout,
                 expected="stdout to contain %r" % errtext,
             ),
         )
 
     def testversiondetection(self):
         """Check the version-detection logic when importing parsers."""
         # Only test the version-detection logic if it is present.
         try:
             parsers.versionerrortext
         except AttributeError:
             return
         info = sys.version_info
         major, minor, micro = info[0], info[1], info[2]
         # Test same major-minor versions.
         self.assertversionokay(1, makehex(major, minor, micro))
         self.assertversionokay(2, makehex(major, minor, micro + 1))
         # Test different major-minor versions.
         self.assertversionfail(3, makehex(major + 1, minor, micro))
         self.assertversionfail(4, makehex(major, minor + 1, micro))
         self.assertversionfail(5, "'foo'")
 
     def testbadargs(self):
         # Check that parse_index2() raises TypeError on bad arguments.
         with self.assertRaises(TypeError):
             parse_index2(0, True)
 
     def testparseindexfile(self):
         # Check parsers.parse_index2() on an index file against the
         # original Python implementation of parseindex, both with and
         # without inlined data.
 
         want = py_parseindex(data_inlined, True)
         got = parse_index2(data_inlined, True)
         self.assertEqual(want, got)  # inline data
 
         want = py_parseindex(data_non_inlined, False)
         got = parse_index2(data_non_inlined, False)
         self.assertEqual(want, got)  # no inline data
 
         ix = parsers.parse_index2(data_inlined, True)[0]
         for i, r in enumerate(ix):
             if r[7] == nullid:
                 i = -1
             try:
                 self.assertEqual(
                     ix[r[7]],
                     i,
                     'Reverse lookup inconsistent for %r' % nodemod.hex(r[7]),
                 )
             except TypeError:
                 # pure version doesn't support this
                 break
 
     def testminusone(self):
         want = (0, 0, 0, -1, -1, -1, -1, nullid)
         index, junk = parsers.parse_index2(data_inlined, True)
         got = index[-1]
         self.assertEqual(want, got)  # inline data
 
         index, junk = parsers.parse_index2(data_non_inlined, False)
         got = index[-1]
         self.assertEqual(want, got)  # no inline data
 
     def testdelitemwithoutnodetree(self):
         index, _junk = parsers.parse_index2(data_non_inlined, False)
 
         def hexrev(rev):
             if rev == nullrev:
                 return b'\xff\xff\xff\xff'
             else:
                 return nodemod.bin('%08x' % rev)
 
         def appendrev(p1, p2=nullrev):
             # node won't matter for this test, let's just make sure
             # they don't collide. Other data don't matter either.
             node = hexrev(p1) + hexrev(p2) + b'.' * 12
             index.append((0, 0, 12, 1, 34, p1, p2, node))
 
         appendrev(4)
         appendrev(5)
         appendrev(6)
         self.assertEqual(len(index), 7)
 
-        del index[1:7]
+        del index[1:-1]
 
         # assertions that failed before correction
         self.assertEqual(len(index), 1)  # was 4
+        headrevs = getattr(index, 'headrevs', None)
+        if headrevs is not None:  # not implemented in pure
         self.assertEqual(index.headrevs(), [0])  # gave ValueError
 
 
 if __name__ == '__main__':
     import silenttestrunner
 
     silenttestrunner.main(__name__)