view tests/test-linerange.py @ 39788:ae531f5e583c

testing: add interface unit tests for file storage

Our strategy for supporting alternate storage backends is to define
interfaces for everything then "code to the interface."

We already have interfaces for various primitives, including file
and manifest storage.

What we don't have is generic unit tests for those interfaces. Up
to this point we've been relying on high-level integration tests
(mainly in the form of existing .t tests) to test alternate storage
backends. And my experience with developing the "simple store" test
extension is that such testing is very tedious: it takes several
minutes to run all tests and when you find a failure, it is often
non-trivial to debug.

This commit starts to change that.

This commit introduces the mercurial.testing.storage module. It
contains testing code for storage. Currently, it defines some
unittest.TestCase classes for testing the file storage interfaces.
It also defines some factory functions that allow a caller to easily
spawn a custom TestCase "bound" to a specific file storage backend
implementation.

A new .py test has been added. It simply defines a callable to produce
filelog and transaction instances on demand and then "registers" the
various test classes so the filelog class can be tested with the
storage interface unit tests.

As part of writing the tests, I identified a couple of apparent
bugs in revlog.py and filelog.py! These are tracked with inline
TODO comments.

Writing the tests makes it more obvious where the storage interface
is lacking. For example, we raise either IndexError or
error.LookupError for missing revisions depending on whether we
use an integer revision or a node. Also, we raise error.RevlogError
in various places when we should be raising a storage-agnostic
error type.

The storage interfaces are currently far from perfect and there is much
work to be done to improve them. But at least with this commit we
finally have the start of unit tests that can be used to "qualify"
the behavior of a storage backend. And when implementing and debugging
new storage backends, we now have an obvious place to define new
tests and have obvious places to insert breakpoints to facilitate
debugging. This should be invaluable when implementing new storage
backends.

I added the mercurial.testing package because these interface
conformance tests are generic and need to be usable by all storage
backends. Having the code live in tests/ would make it difficult for
storage backends implemented in extensions to test their interface
conformance. First, it would require obtaining a copy of Mercurial's
storage test code in order to test. Second, it would make testing
against multiple Mercurial versions difficult, as you would need to
import N copies of the storage testing code in order to achieve test
coverage. By making the test code part of the Mercurial distribution
itself, extensions can `import mercurial.testing.*` to access and run
the test code. The test will run against whatever Mercurial version
is active.

FWIW I've always wanted to move parts of run-tests.py into the
mercurial.* package to make the testing story simpler (e.g. imagine an
`hg debugruntests` command that could invoke the test harness). While I
have no plans to do that in the near future, establishing the
mercurial.testing package does provide a natural home for that code
should someone do this in the future.

Differential Revision: https://phab.mercurial-scm.org/D4650

from __future__ import absolute_import

import unittest
from mercurial import error, mdiff

# for readability, line numbers are 0-origin
text1 = b'''
           00 at OLD
           01 at OLD
           02 at OLD
02 at NEW, 03 at OLD
03 at NEW, 04 at OLD
04 at NEW, 05 at OLD
05 at NEW, 06 at OLD
           07 at OLD
           08 at OLD
           09 at OLD
           10 at OLD
           11 at OLD
'''[1:] # strip initial LF

text2 = b'''
00 at NEW
01 at NEW
02 at NEW, 03 at OLD
03 at NEW, 04 at OLD
04 at NEW, 05 at OLD
05 at NEW, 06 at OLD
06 at NEW
07 at NEW
08 at NEW
09 at NEW
10 at NEW
11 at NEW
'''[1:] # strip initial LF

def filteredblocks(blocks, rangeb):
    """return `rangea` extracted from `blocks` coming from
    `mdiff.blocksinrange` along with the mask of blocks within rangeb.
    """
    filtered, rangea = mdiff.blocksinrange(blocks, rangeb)
    skipped = [b not in filtered for b in blocks]
    return rangea, skipped

class blocksinrangetests(unittest.TestCase):

    def setUp(self):
        self.blocks = list(mdiff.allblocks(text1, text2))
        assert self.blocks == [
            ([0, 3, 0, 2], b'!'),
            ((3, 7, 2, 6), b'='),
            ([7, 12, 6, 12], b'!'),
            ((12, 12, 12, 12), b'='),
        ], self.blocks

    def testWithinEqual(self):
        """linerange within an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #        ^^
        linerange2 = (3, 5)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (4, 6))
        self.assertEqual(skipped, [True, False, True, True])

    def testWithinEqualStrictly(self):
        """linerange matching exactly an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #       ^^^^
        linerange2 = (2, 6)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (3, 7))
        self.assertEqual(skipped, [True, False, True, True])

    def testWithinEqualLowerbound(self):
        """linerange at beginning of an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #       ^^
        linerange2 = (2, 4)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (3, 5))
        self.assertEqual(skipped, [True, False, True, True])

    def testWithinEqualLowerboundOneline(self):
        """oneline-linerange at beginning of an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #       ^
        linerange2 = (2, 3)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (3, 4))
        self.assertEqual(skipped, [True, False, True, True])

    def testWithinEqualUpperbound(self):
        """linerange at end of an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #        ^^^
        linerange2 = (3, 6)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (4, 7))
        self.assertEqual(skipped, [True, False, True, True])

    def testWithinEqualUpperboundOneLine(self):
        """oneline-linerange at end of an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #          ^
        linerange2 = (5, 6)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (6, 7))
        self.assertEqual(skipped, [True, False, True, True])

    def testWithinFirstBlockNeq(self):
        """linerange within the first "!" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #     ^
        #      |           (empty)
        #      ^
        #     ^^
        for linerange2 in [
            (0, 1),
            (1, 1),
            (1, 2),
            (0, 2),
        ]:
            linerange1, skipped = filteredblocks(self.blocks, linerange2)
            self.assertEqual(linerange1, (0, 3))
            self.assertEqual(skipped, [False, True, True, True])

    def testWithinLastBlockNeq(self):
        """linerange within the last "!" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #           ^
        #            ^
        #           |      (empty)
        #           ^^^^^^
        #                ^
        for linerange2 in [
            (6, 7),
            (7, 8),
            (7, 7),
            (6, 12),
            (11, 12),
        ]:
            linerange1, skipped = filteredblocks(self.blocks, linerange2)
            self.assertEqual(linerange1, (7, 12))
            self.assertEqual(skipped, [True, True, False, True])

    def testAccrossTwoBlocks(self):
        """linerange accross two blocks"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #      ^^^^
        linerange2 = (1, 5)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (0, 6))
        self.assertEqual(skipped, [False, False, True, True])

    def testCrossingSeveralBlocks(self):
        """linerange accross three blocks"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #      ^^^^^^^
        linerange2 = (1, 8)
        linerange1, skipped = filteredblocks(self.blocks, linerange2)
        self.assertEqual(linerange1, (0, 12))
        self.assertEqual(skipped, [False, False, False, True])

    def testStartInEqBlock(self):
        """linerange starting in an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #          ^^^^
        #         ^^^^^^^
        for linerange2, expectedlinerange1 in [
            ((5, 9), (6, 12)),
            ((4, 11), (5, 12)),
        ]:
            linerange1, skipped = filteredblocks(self.blocks, linerange2)
            self.assertEqual(linerange1, expectedlinerange1)
            self.assertEqual(skipped, [True, False, False, True])

    def testEndInEqBlock(self):
        """linerange ending in an "=" block"""
        # IDX 0         1
        #     012345678901
        # SRC NNOOOONNNNNN (New/Old)
        #      ^^
        #     ^^^^^
        for linerange2, expectedlinerange1 in [
            ((1, 3), (0, 4)),
            ((0, 4), (0, 5)),
        ]:
            linerange1, skipped = filteredblocks(self.blocks, linerange2)
            self.assertEqual(linerange1, expectedlinerange1)
            self.assertEqual(skipped, [False, False, True, True])

    def testOutOfRange(self):
        """linerange exceeding file size"""
        exctype = error.Abort
        for linerange2 in [
            (0, 34),
            (15, 12),
        ]:
            # Could be `with self.assertRaises(error.Abort)` but python2.6
            # does not have assertRaises context manager.
            try:
                mdiff.blocksinrange(self.blocks, linerange2)
            except exctype as exc:
                self.assertTrue('line range exceeds file size' in str(exc))
            else:
                self.fail('%s not raised' % exctype.__name__)

if __name__ == '__main__':
    import silenttestrunner
    silenttestrunner.main(__name__)