comparison tests/test-help.t @ 27379:2278870bb997

help: support loading sub-topics

If a sub-topic/section is requested and the main topic corresponds to
a topic with sub-topics, we now look for and return content for a
sub-topic if found.

With this patch, `hg help internals.X` now works. hgweb does not yet
render sub-topics, however.

27378:c709b515218e

  """""""""""""""""""""""""""""""
  
       bundles       container for exchange of repository data
       changegroups  representation of revlog data

Test list of commands with command with no help text

  $ hg help helpext
  helpext extension - no help text available
  

27379:2278870bb997

  """""""""""""""""""""""""""""""
  
       bundles       container for exchange of repository data
       changegroups  representation of revlog data

sub-topics can be accessed

  $ hg help internals.changegroups
      Changegroups
      ============
  
      Changegroups are representations of repository revlog data, specifically
      the changelog, manifest, and filelogs.
  
      There are 2 versions of changegroups: "1" and "2". From a high-level, they
      are almost exactly the same, with the only difference being a header on
      entries in the changeset segment.
  
      Changegroups consists of 3 logical segments:
  
        +---------------------------------+
        |           |          |          |
        | changeset | manifest | filelogs |
        |           |          |          |
        +---------------------------------+
  
      The principle building block of each segment is a *chunk*. A *chunk* is a
      framed piece of data:
  
        +---------------------------------------+
        |           |                           |
        |  length   |           data            |
        | (32 bits) |       <length> bytes      |
        |           |                           |
        +---------------------------------------+
  
      Each chunk starts with a 32-bit big-endian signed integer indicating the
      length of the raw data that follows.
  
      There is a special case chunk that has 0 length ("0x00000000"). We call
      this an *empty chunk*.
  
      Delta Groups
      ------------
  
      A *delta group* expresses the content of a revlog as a series of deltas,
      or patches against previous revisions.
  
      Delta groups consist of 0 or more *chunks* followed by the *empty chunk*
      to signal the end of the delta group:
  
        +------------------------------------------------------------------------+
        |                |             |               |             |           |
        | chunk0 length  | chunk0 data | chunk1 length | chunk1 data |    0x0    |
        |   (32 bits)    |  (various)  |   (32 bits)   |  (various)  | (32 bits) |
        |                |             |               |             |           |
        +------------------------------------------------------------+-----------+
  
      Each *chunk*'s data consists of the following:
  
        +-----------------------------------------+
        |              |              |           |
        | delta header | mdiff header |   delta   |
        |  (various)   |  (12 bytes)  | (various) |
        |              |              |           |
        +-----------------------------------------+
  
      The *length* field is the byte length of the remaining 3 logical pieces of
      data. The *delta* is a diff from an existing entry in the changelog.
  
      The *delta header* is different between versions "1" and "2" of the
      changegroup format.
  
      Version 1:
  
        +------------------------------------------------------+
        |            |             |             |             |
        |    node    |   p1 node   |   p2 node   |  link node  |
        | (20 bytes) |  (20 bytes) |  (20 bytes) |  (20 bytes) |
        |            |             |             |             |
        +------------------------------------------------------+
  
      Version 2:
  
        +------------------------------------------------------------------+
        |            |             |             |            |            |
        |    node    |   p1 node   |   p2 node   | base node  | link node  |
        | (20 bytes) |  (20 bytes) |  (20 bytes) | (20 bytes) | (20 bytes) |
        |            |             |             |            |            |
        +------------------------------------------------------------------+
  
      The *mdiff header* consists of 3 32-bit big-endian signed integers
      describing offsets at which to apply the following delta content:
  
        +-------------------------------------+
        |           |            |            |
        |  offset   | old length | new length |
        | (32 bits) |  (32 bits) |  (32 bits) |
        |           |            |            |
        +-------------------------------------+
  
      In version 1, the delta is always applied against the previous node from
      the changegroup or the first parent if this is the first entry in the
      changegroup.
  
      In version 2, the delta base node is encoded in the entry in the
      changegroup. This allows the delta to be expressed against any parent,
      which can result in smaller deltas and more efficient encoding of data.
  
      Changeset Segment
      -----------------
  
      The *changeset segment* consists of a single *delta group* holding
      changelog data. It is followed by an *empty chunk* to denote the boundary
      to the *manifests segment*.
  
      Manifest Segment
      ----------------
  
      The *manifest segment* consists of a single *delta group* holding manifest
      data. It is followed by an *empty chunk* to denote the boundary to the
      *filelogs segment*.
  
      Filelogs Segment
      ----------------
  
      The *filelogs* segment consists of multiple sub-segments, each
      corresponding to an individual file whose data is being described:
  
        +--------------------------------------+
        |          |          |          |     |
        | filelog0 | filelog1 | filelog2 | ... |
        |          |          |          |     |
        +--------------------------------------+
  
      The final filelog sub-segment is followed by an *empty chunk* to denote
      the end of the segment and the overall changegroup.
  
      Each filelog sub-segment consists of the following:
  
        +------------------------------------------+
        |               |            |             |
        | filename size |  filename  | delta group |
        |   (32 bits)   |  (various) |  (various)  |
        |               |            |             |
        +------------------------------------------+
  
      That is, a *chunk* consisting of the filename (not terminated or padded)
      followed by N chunks constituting the *delta group* for this file.

Test list of commands with command with no help text

  $ hg help helpext
  helpext extension - no help text available