* jk/unit-tests-buildfix:
  t/Makefile: say the default target upfront
  t/Makefile: get UNIT_TESTS list from C sources
  Makefile: remove UNIT_TEST_BIN directory with "make clean"
  Makefile: use mkdir_p_parent_template for UNIT_TEST_BIN

While t/unit-tests/t-basic.c uses the unit-test framework added in
e137fe3 (unit tests: add TAP unit test framework, 2023-11-09), it is
not a true unit test in that it intentionally fails in order to exercise
various codepaths in the unit-test framework. Thus, we intentionally
exclude it when running unit tests through the various t/Makefile
targets. Instead, it is executed by t0080-unit-test-output.sh, which
verifies its output follows the TAP format expected for the various
pass, skip, or fail cases.

As such, it makes more sense for t-basic to be a helper item for
t0080-unit-test-output.sh, so let's move it to
t/helper/test-example-tap.c and adjust Makefiles as necessary.

Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

When running tests through `test-tool run-command testsuite`, we
currently hardcode `sh` as the command interpreter. As discussed in [1],
this is incorrect, and we should be using the shell set in
TEST_SHELL_PATH instead.

Add a shell_path field in struct testsuite so that we can pass this to
the task runner callback. If this is non-null, we'll use it as the
argv[0] of the subprocess. Otherwise, we'll just execute the test
program directly. We will use this feature in a later commit to enable
running binary executable unit tests.

However, for now when setting up the struct testsuite in testsuite(),
use the value of TEST_SHELL_PATH if it's set, otherwise keep the
original behavior by defaulting to `sh`.

[1] https://lore.kernel.org/git/[email protected]/

Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

`test-tool run-command testsuite` currently assumes that it will only be
running the shell test suite, and therefore filters out anything that
does not match a hardcoded pattern of "t[0-9][0-9][0-9][0-9]-*.sh".

Later in this series, we'll adapt `test-tool run-command testsuite` to
also support unit tests, which do not follow the same naming conventions
as the shell tests, so this hardcoded pattern is inconvenient.

Since `testsuite` also allows specifying patterns on the command-line,
let's just remove this pattern. As noted in [1], there are no longer any
uses of `testsuite` in our codebase, it should be OK to break backwards
compatibility in this case. We also add a new filter to avoid trying to
execute "." and "..", so that users who wish to execute every test in a
directory can do so without specifying a pattern.

[1] https://lore.kernel.org/git/[email protected]/

Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Teach the testsuite runner in `test-tool run-command testsuite` how to
run unit tests: if TEST_SHELL_PATH is not set, run the programs directly
from CWD, rather than defaulting to "sh" as an interpreter.

With this change, you can now use test-tool to run the unit tests:
$ make
$ cd t/unit-tests/bin
$ ../../helper/test-tool run-command testsuite

This should be helpful on Windows to allow running tests without
requiring Perl (for `prove`), as discussed in [1] and [2].

This again breaks backwards compatibility, as it is now required to set
TEST_SHELL_PATH properly for executing shell scripts, but again, as
noted in [2], there are no longer any such invocations in our codebase.

[1] https://lore.kernel.org/git/[email protected]/
[2] https://lore.kernel.org/git/[email protected]/

Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

In the previous commit, we added support in test-tool for running
collections of unit tests. Now, add rules in t/Makefile for running in
this way.

This new rule can be executed from the top-level Makefile via
`make DEFAULT_UNIT_TEST_TARGET=unit-tests-test-tool unit-tests`, or by
setting DEFAULT_UNIT_TEST_TARGET in config.mak.

Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Add a wrapper script to allow `prove` to run both shell tests and unit
tests from a single invocation. This avoids issues around running prove
twice in CI, as discussed in [1].

Additionally, this moves the unit tests into the main dev workflow, so
that errors can be spotted more quickly. Accordingly, we remove the
separate unit tests step for Linux CI. (We leave the Windows CI
unit-test step as-is, because the sharding scheme there involves
selecting specific test files rather than running `make test`.)

[1] https://lore.kernel.org/git/[email protected]/

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Although the previous commit changed t/Makefile to run unit tests
alongside shell tests, the Windows CI still needs a separate unit-tests
step due to how the test sharding works.

We want to avoid using `prove` as a test running on Windows due to
performance issues [1], so use the new test-tool runner instead.

[1] https://lore.kernel.org/git/[email protected]/

Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

The `test-tool` recently learned to run the unit tests. To this end, it
needs to link with `test-lib.c`, which was done in the `Makefile`, and
this patch does it in the CMake definition, too.

This is a companion of 44400f5 (t0080: turn t-basic unit test into
a helper, 2024-02-02).

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>