view tests/test-issue1877.t @ 44143:7f86426fdd2c

rust-node: binary Node ID and conversion utilities

The choice of type makes sure that a `Node` has the exact
wanted size. We'll use a different type for prefixes.

Added dependency: hexadecimal conversion relies on the
`hex` crate.

The fact that sooner or later Mercurial is going to need
to change its hash sizes has been taken strongly in
consideration:

- the hash length is a constant, but that is not directly
  exposed to callers. Changing the value of that constant
  is the only thing to do to change the hash length (even
  in unit tests)
- the code could be adapted to support several sizes of hashes,
  if that turned out to be useful. To that effect, only the
  size of a given `Node` is exposed in the public API.
- callers not involved in initial computation, I/O and FFI
  are able to operate without a priori assumptions on the hash
  size. The traits `FromHex` and `ToHex` have not been directly
  implemented, so that the doc-comments explaining these
  restrictions would stay really visible in `cargo doc`

Differential Revision: https://phab.mercurial-scm.org/D7788

https://bz.mercurial-scm.org/1877

  $ hg init a
  $ cd a
  $ echo a > a
  $ hg add a
  $ hg ci -m 'a'
  $ echo b > a
  $ hg ci -m'b'
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg book main
  $ hg book
   * main                      0:cb9a9f314b8b
  $ echo c > c
  $ hg add c
  $ hg ci -m'c'
  created new head
  $ hg book
   * main                      2:d36c0562f908
  $ hg heads
  changeset:   2:d36c0562f908
  bookmark:    main
  tag:         tip
  parent:      0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     c
  
  changeset:   1:1e6c11564562
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b
  
  $ hg up 1e6c11564562
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark main)
  $ hg merge main
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg book
     main                      2:d36c0562f908
  $ hg ci -m'merge'
  $ hg book
     main                      2:d36c0562f908

  $ cd ..