First make sure you read and understand our general guidelines and suggestions for microprojects.

There are some suggestions on how you can find some microprojects on your own in the document.

Ideas for microprojects

Add more builtin patterns for userdiff

“git diff” shows the function name corresponding to each hunk after the @@ … @@ line. For common languages (C, HTML, Ada, Matlab, …), the way to find the function name is built-in Git’s source code as regular expressions (see userdiff.c). A few languages are common enough to deserve a built-in driver, but are not yet recognized. For example, shell.

This project requires a very good knowledge of regular expressions.

It is easy though to find examples of how this can be done by searching the code base and the mailing list archive, as this has already been done for a number of languages.

Replace a run_command*() call by direct calls to C functions

See for example what Junio did in ffcb4e94d3 (bisect: do not run show-branch just to show the current commit, 2021-07-27).

If you can’t find one please tell us, along with the command you used to search, so that we can remove this microproject idea.

Use test_path_is_* functions in test scripts

Find one test script that verifies the presence/absence of files/directories with ‘test -(e|f|d|…)’ and replace them with the appropriate test_path_is_file, test_path_is_dir, etc. helper functions. Note that this conversion does not directly apply to control flow constructs like if test -e ./path; then ...; fi because the replacements are intended to assert the condition instead of merely testing for it. Check this link for an elaborate clarification on identifying test -e instances that should / should not be replaced.

If you can’t find one please tell us, along with the command you used to search, so that we can remove this microproject idea.

Avoid suppressing git’s exit code in test scripts

The Git project uses a large collection of integration tests written in Shell to guard against regressions when adding new features or fixing bugs. The scripts in question can be found in the t directory here.

While it is perfectly OK to use pipes when writing integration tests, we must be careful to avoid writing a pipeline that suppresses the exit code of a Git process, like so:

git <subcommand> | <some other command>

…since the exit code of git <subcommand> would be suppressed by the pipe. If git <subcommand> crashed, we would not catch it in the above example when running the integration suite.

Other examples to avoid include:

# bad:
<some command> $(git <subcommand>)

# also bad:
<some command> <<EOF
... some text ...
$(git <subcommand>)

…since the exit code of git <subcommand> is hidden behind the subshell in both instances.

On the other hand, both of the following examples are OK, since neither hides the exit code of running git <subcommand>:

# good:
var=$(git <subcommand>)

# also good:
<some command> | <some other command> | git <subcommand>

(provided that neither <some command> or <some other command> are git).

See the commit c6f44e1da5 for example, and then do the same thing in one other test script.

If you can’t find one please tell us, along with the command you used to search, so that we can remove this microproject idea.

Use unsigned integral type for collection of bits.

Pick one field of a structure that (1) is of signed integral type and (2) is used as a collection of multiple bits. Discuss if there is a good reason why it has to be a signed integral field and change it to an unsigned type otherwise. [thread]

Even though the amount of code to write is small, these projects involve a lot of prior work to understand the specification and deal with all potential corner-cases.

Modernize a test script

A number of our test scripts have been written a long time ago in a style that is now outdated.

In the following email it is explained in details how to modernize and clean up the t7001 test script:

t7001 is not the only test script where similar changes could be made though.

Find one test script that needs some of the same changes and make them. Please make sure that the test script is not already being worked on by asking on the mailing list before starting to work on it.

There should be only one kind of change per commit. For example if one of your commits indents test bodies with TABs, instead of spaces, then this should be the only kind of change in this commit.