t0410: make test description clearer

[git/gitster.git] / po / README.md

# Core GIT Translations

This directory holds the translations for the core of Git. This document
describes how you can contribute to the effort of enhancing the language
coverage and maintaining the translation.

The localization (l10n) coordinator, Jiang Xin <worldhello.net@gmail.com>,
coordinates our localization effort in the l10n coordinator repository:

    https://github.com/git-l10n/git-po/

We will use XX as an alias to refer to the language translation code in
the following paragraphs, for example we use "po/XX.po" to refer to the
translation file for a specific language. But this doesn't mean that
the language code has only two letters. The language code can be in one
of two forms: "ll" or "ll\_CC". Here "ll" is the ISO 639 two-letter
language code and "CC" is the ISO 3166 two-letter code for country names
and subdivisions. For example: "de" for German language code, "zh\_CN"
for Simplified Chinese language code.


## Contributing to an existing translation

As a contributor for a language XX, you should first check TEAMS file in
this directory to see whether a dedicated repository for your language XX
exists. Fork the dedicated repository and start to work if it exists.

Sometime, contributors may find that the translations of their Git
distributions are quite different with the translations of the
corresponding version from Git official. This is because some Git
distributions (such as from Ubuntu, etc.) have their own l10n workflow.
For this case, wrong translations should be reported and fixed through
their workflows.


## Creating a new language translation

If you are the first contributor for the language XX, please fork this
repository, prepare and/or update the translated message file "po/XX.po"
(described later), and ask the l10n coordinator to pull your work.

If there are multiple contributors for the same language, please first
coordinate among yourselves and nominate the team leader for your
language, so that the l10n coordinator only needs to interact with one
person per language.


## Translation Process Flow

The overall data-flow looks like this:

    +-------------------+             +------------------+
    | Git source code   | ----(2)---> | L10n coordinator |
    | repository        | <---(5)---- | repository       |
    +-------------------+             +------------------+
                    |                     |    ^
                   (1)                   (3)  (4)
                    V                     v    |
               +----------------------------------+
               |        Language Team XX          |
               +----------------------------------+

- Translatable strings are marked in the source file.
- Language teams can start translation iterations at any time, even
  before the l10n window opens:

  + Pull from the master branch of the source (1)
  + Update the message file by running "make po-update PO\_FILE=po/XX.po"
  + Translate the message file "po/XX.po"

- The L10n coordinator pulls from source and announces the l10n window
  open (2)
- Language team pulls from the l10n coordinator, starts another
  translation iteration against the l10n coordinator's tree (3)

  + Run "git pull --rebase" from the l10n coordinator
  + Update the message file by running "make po-update PO\_FILE=po/XX.po"
  + Translate the message file "po/XX.po"
  + Squash trivial l10n git commits using "git rebase -i"

- Language team sends pull request to the l10n coordinator (4)
- L10n coordinator checks and merges
- L10n coordinator asks the result to be pulled (5).


## Dynamically generated POT files

POT files are templates for l10n contributors to create or update their
translation files. We used to have the "po/git.pot" file which was
generated by the l10n coordinator, but this file had been removed from
the tree.

The two POT files "po/git.pot" and "po/git-core.pot" can be created
dynamically when necessary.

L10n contributors use "po/git.pot" to prepare translations for their
languages, but they are not expected to modify it. The "po/git.pot" file
can be generated manually with the following command:

```shell
make po/git.pot
```

The "po/git-core.pot" file is the template for core translations. A core
translation is the minimum set of work necessary to complete a
translation of a new language. Since there are more than 5000 messages
in the full set of template message file "po/git.pot" that need to be
translated, this is not a piece of cake for new language contributors.

The "core" template file "po/git-core.pot" can be generated manually
by running:

```shell
make po/git-core.pot
```


## Initializing a "XX.po" file

(This is done by the language teams).

If your language XX does not have translated message file "po/XX.po" yet,
you add a translation for the first time by running:

```shell
make po-init PO_FILE=po/XX.po
```

where XX is the locale, e.g. "de", "is", "pt\_BR", "zh\_CN", etc.

The newly generated message file "po/XX.po" is based on the core pot
file "po/git-core.pot", so it contains only a minimal set of messages
and it's a good start for a new language contribution.

Once you are done testing the translation (see below), commit the result
and ask the l10n coordinator to pull from you.


## Updating a "XX.po" file

(This is done by the language teams).

If you are replacing translation strings in an existing "XX.po" file to
improve the translation, just edit the file.

If you want to find new translatable strings in source files of upstream
repository and propagate them to your "po/XX.po", run command:

```shell
make po-update PO_FILE=po/XX.po
```

It will:

- Call "make po/git.pot" to generate new "po/git.pot" file
- Call "msgmerge --add-location --backup=off -U po/XX.po po/git.pot"
  to update your "po/XX.po"
- The "--add-location" option for msgmerge will add location lines,
  and these location lines will help translation tools to locate
  translation context easily.

Once you are done testing the translation (see below), it's better
to commit a location-less "po/XX.po" file to save repository space
and make a user-friendly patch for review.

To save a location-less "po/XX.po" automatically in repository, you
can:

First define a new attribute for "po/XX.po" by appending the following
line in ".git/info/attributes":

```
/po/XX.po filter=gettext-no-location
```

Then define the driver for the "gettext-no-location" clean filter to
strip out both filenames and locations from the contents as follows:

```shell
git config --global filter.gettext-no-location.clean \
           "msgcat --no-location -"
```

For users who have gettext version 0.20 or higher, it is also possible
to define a clean filter to preserve filenames but not locations:

```shell
git config --global filter.gettext-no-location.clean \
           "msgcat --add-location=file -"
```

You're now ready to ask the l10n coordinator to pull from you.


## Fuzzy translation

Fuzzy translation is a translation marked by comment "fuzzy" to let you
know that the translation is out of date because the "msgid" has been
changed. A fuzzy translation will be ignored when compiling using "msgfmt".
Fuzzy translation can be marked by hands, but for most cases they are
marked automatically when running "msgmerge" to update your "XX.po" file.

After fixing the corresponding translation, you must remove the "fuzzy"
tag in the comment.


## Testing your changes

(This is done by the language teams, after creating or updating "XX.po" file).

Before you submit your changes go back to the top-level and do:

```shell
make
```

On systems with GNU gettext (i.e. not Solaris) this will compile your
changed PO file with `msgfmt --check`, the --check option flags many
common errors, e.g. missing printf format strings, or translated
messages that deviate from the originals in whether they begin/end
with a newline or not.

L10n coordinator will check your contributions using a helper program
(see "PO helper" section below):

```shell
git-po-helper check-po po/XX.po
git-po-helper check-commits <rev-list-opts>
```


## Marking strings for translation

(This is done by the core developers).

Before strings can be translated they first have to be marked for
translation.

Git uses an internationalization interface that wraps the system's
gettext library, so most of the advice in your gettext documentation
(on GNU systems `info gettext` in a terminal) applies.

General advice:

- Don't mark everything for translation, only strings which will be
  read by humans (the porcelain interface) should be translated.

  The output from Git's plumbing utilities will primarily be read by
  programs and would break scripts under non-C locales if it was
  translated. Plumbing strings should not be translated, since
  they're part of Git's API.

- Adjust the strings so that they're easy to translate. Most of the
  advice in `info '(gettext)Preparing Strings'` applies here.

- Strings referencing numbers of items may need to be split into singular and
  plural forms; see the Q\_() wrapper in the C sub-section below for an
  example.

- If something is unclear or ambiguous you can use a "TRANSLATORS"
  comment to tell the translators what to make of it. These will be
  extracted by xgettext(1) and put in the "po/\*.po" files, e.g. from
  git-am.sh:

  ```shell
  # TRANSLATORS: Make sure to include [y], [n], [e], [v] and [a]
  # in your translation. The program will only accept English
  # input at this point.
  gettext "Apply? [y]es/[n]o/[e]dit/[v]iew patch/[a]ccept all "
  ```

  Or in C, from builtin/revert.c:

  ```c
  /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
  die(_("%s: Unable to write new index file"), action_name(opts));
  ```

We provide wrappers for C, Shell and Perl programs. Here's how they're
used:


### C

Include builtin.h at the top, it'll pull in gettext.h, which
defines the gettext interface. Consult with the list if you need to
use gettext.h directly.

The C interface is a subset of the normal GNU gettext
interface. We currently export these functions:

- \_()

  Mark and translate a string. E.g.:

  ```c
  printf(_("HEAD is now at %s"), hex);
  ```

- Q\_()

  Mark and translate a plural string. E.g.:

  ```c
  printf(Q_("%d commit", "%d commits", number_of_commits));
  ```

  This is just a wrapper for the ngettext() function.

- N\_()

  A no-op pass-through macro for marking strings inside static
  initializations, e.g.:

  ```c
  static const char *reset_type_names[] = {
      N_("mixed"), N_("soft"), N_("hard"), N_("merge"), N_("keep"), NULL
  };
  ```

  And then, later:

  ```c
  die(_("%s reset is not allowed in a bare repository"),
        _(reset_type_names[reset_type]));
  ```

  Here `_()` couldn't have statically determined what the translation
  string will be, but since it was already marked for translation
  with `N_()` the look-up in the message catalog will succeed.


### Shell

The Git gettext shell interface is just a wrapper for
gettext.sh. Import it right after git-sh-setup like this:

```shell
. git-sh-setup
. git-sh-i18n
```

And then use the `gettext` or `eval_gettext` functions:

```shell
# For constant interface messages:
gettext "A message for the user"; echo

# To interpolate variables:
details="oh noes"
eval_gettext "An error occurred: \$details"; echo
```

In addition we have wrappers for messages that end with a trailing
newline. I.e. you could write the above as:

```shell
# For constant interface messages:
gettextln "A message for the user"

# To interpolate variables:
details="oh noes"
eval_gettextln "An error occurred: \$details"
```

More documentation about the interface is available in the GNU info
page: `info '(gettext)sh'`. Looking at git-am.sh (the first shell
command to be translated) for examples is also useful:

```shell
git log --reverse -p --grep=i18n git-am.sh
```


### Perl

The Git::I18N module provides a limited subset of the
Locale::Messages functionality, e.g.:

```perl
use Git::I18N;
print __("Welcome to Git!\n");
printf __("The following error occurred: %s\n"), $error;
```

Run `perldoc perl/Git/I18N.pm` for more info.


## Testing marked strings

Git's tests are run under `LANG=C LC_ALL=C`. So the tests do not need be
changed to account for translations as they're added.


## PO helper

To make the maintenance of "XX.po" easier, the l10n coordinator and l10n
team leaders can use a helper program named "git-po-helper". It is a
wrapper to gettext suite, specifically written for the purpose of Git
l10n workflow.

To build and install the helper program from source, see
[git-po-helper/README][].


## Conventions

There are some conventions that l10n contributors must follow:

- The subject of each l10n commit should be prefixed with "l10n: ".

- Do not use non-ASCII characters in the subject of a commit.

- The length of commit subject (first line of the commit log) should
  be no more than 50 characters, and the length of other lines of the
  commit log should be no more than 72 characters.

- Add "Signed-off-by" trailer to your commit log, like other commits
  in Git. You can automatically add the trailer by committing with
  the following command:

  ```shell
  git commit -s
  ```

- Check syntax with "msgfmt" or the following command before creating
  your commit:

  ```shell
  git-po-helper check-po <XX.po>
  ```

- Squash trivial commits to make history clear.

- DO NOT edit files outside "po/" directory.

- Other subsystems ("git-gui", "gitk", and Git itself) have their
  own workflow. See [Documentation/SubmittingPatches][] for
  instructions on how to contribute patches to these subsystems.


To contribute for a new l10n language, contributor should follow
additional conventions:

- Initialize proper filename of the "XX.po" file conforming to
  iso-639 and iso-3166.

- Must complete a minimal translation based on the "Core
  translation". See that section above.

- Add a new entry in the "po/TEAMS" file with proper format, and check
  the syntax of "po/TEAMS" by running the following command:

  ```shell
  git-po-helper team --check
  ```


[git-po-helper/README]: https://github.com/git-l10n/git-po-helper#readme
[Documentation/SubmittingPatches]: Documentation/SubmittingPatches