view tests/test-diff-issue2761.t @ 37208:b9dd8403d8ff

zope: force module import by importing symbols

Previously, we tried to import a module and handle the ImportError.
Our lazy module importer doesn't verify the module exists and returns
a dummy object representing the module. Only once we attempt to load
a symbol in the module does the ImportError get raises.

This means that simple imports inside `try..except ImportError` don't
detect missing modules.

This commit changes imports in zope.interface to access symbols, thus
forcing module load and triggering ImportError.

This fixes zope.interface for pure builds.

Differential Revision: https://phab.mercurial-scm.org/D2980

Test issue2761

  $ hg init

  $ touch to-be-deleted
  $ hg add
  adding to-be-deleted
  $ hg ci -m first
  $ echo a > to-be-deleted
  $ hg ci -m second
  $ rm to-be-deleted
  $ hg diff -r 0

Same issue, different code path

  $ hg up -C
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ touch does-not-exist-in-1
  $ hg add
  adding does-not-exist-in-1
  $ hg ci -m third
  $ rm does-not-exist-in-1
  $ hg diff -r 1