tests/test-push-checkheads-pruned-B3.t

stringutil: improve check for failed mailmap line parsing

The existing check for a bad mailmap file entry fails with inputs
like b'>@<'. This commit adds a function to check if a sufficient
amount of information has been parsed from a mailmap file entry.

At minimum, one email must be found (assumed to be the commit email).
If email is not empty and no names are found, then there must be
two emails. If there are at least one email and name, the mapping
is valid.

Differential Revision: https://phab.mercurial-scm.org/D3003

====================================
Testing head checking code: Case B-3
====================================

Mercurial checks for the introduction of new heads on push. Evolution comes
into play to detect if existing branches on the server are being replaced by
some of the new one we push.

This case is part of a series of tests checking this behavior.

Category B: simple case involving pruned changesets
TestCase 3: multi-changeset branch, other is pruned, rest is superceeded

.. old-state:
..
.. * 2 changeset branch
..
.. new-state:
..
.. * old head is superceeded
.. * old other is pruned
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
..   B ø⇠◔ B'
..     | |
..   A ⊗ |
..     |/
..     ●

  $ . $TESTDIR/testlib/push-checkheads-util.sh

Test setup
----------

  $ mkdir B3
  $ cd B3
  $ setuprepos
  creating basic server and client repo
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd server
  $ mkcommit B0
  $ cd ../client
  $ hg pull
  pulling from $TESTTMP/B3/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets d73caddc5533
  (run 'hg update' to get a working copy)
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit B1
  created new head
  $ hg debugobsolete --record-parents `getid "desc(A0)"`
  obsoleted 1 changesets
  1 new orphan changesets
  $ hg debugobsolete `getid "desc(B0)" ` `getid "desc(B1)"`
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  25c56d33e4c4 (draft): B1
  |
  | x  d73caddc5533 (draft): B0
  | |
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

Actual testing
--------------

  $ hg push
  pushing to $TESTTMP/B3/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  2 new obsolescence markers
  obsoleted 2 changesets

  $ cd ../..