Re: [PATCH v4 5/7] tracetool: add test suite for tracetool with reference output

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Tue, Aug 19, 2025 at 05:10:51PM +0100, Daniel P. Berrangé wrote:
> When reviewing tracetool patches it is often very unclear what the
> expected output will be for the generated backends. Compounding
> this is that a default build will only enable the 'log' trace
> backend, so developers won't see generated code for other backends
> without making a special effort. Some backends are also platform
> specific, so can't be enabled in QEMU builds, even though tracetool
> could generate the code.
> 
> To address this, introduce a test suite for tracetool which is
> conceptually similar to the qapi-schema test. It is a simple
> python program that runs tracetool and compares the actual output
> to historical reference output kept in git. The test directly
> emits TAP format logs for ease of integration with meson.
> 
> This can be run with
> 
>   make check-tracetool
> 
> to make it easier for developers changing generated output, the
> sample expected content can be auto-recreated
> 
>   QEMU_TEST_REGENERATE=1 make check-tracetool
> 
> and the changes reviewed and added to the commit. This will also
> assist reviewers interpreting the change.
> 
> Developers are reminded of this in the test output on failure:
> 
>   $ make check-tracetool
>   1/6 qemu:tracetool / dtrace        OK              0.14s
>   2/6 qemu:tracetool / ftrace        FAIL            0.06s   exit status 1
>   ――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
>   1..2
>   ok 1 - ftrace.c
>   #
>   not ok 1 - ftrace.h (set QEMU_TEST_REGENERATE=1 to recreate reference output if tracetool generator was intentionally changed)
>   ――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
> 
>   3/6 qemu:tracetool / log           OK              0.06s
>   4/6 qemu:tracetool / simple        OK              0.06s
>   5/6 qemu:tracetool / syslog        OK              0.06s
>   6/6 qemu:tracetool / ust           OK              0.11s
> 
>   Summary of Failures:
> 
>   2/6 qemu:tracetool / ftrace FAIL            0.06s   exit status 1
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  MAINTAINERS                             |   1 +
>  docs/devel/testing/main.rst             |  28 +++++++
>  tests/Makefile.include                  |   1 +
>  tests/meson.build                       |   1 +
>  tests/tracetool/dtrace.c                |  32 ++++++++
>  tests/tracetool/dtrace.d                |  10 +++
>  tests/tracetool/dtrace.h                |  59 +++++++++++++
>  tests/tracetool/dtrace.log-stap         |  15 ++++
>  tests/tracetool/dtrace.simpletrace-stap |  16 ++++
>  tests/tracetool/dtrace.stap             |  14 ++++
>  tests/tracetool/ftrace.c                |  32 ++++++++
>  tests/tracetool/ftrace.h                |  73 ++++++++++++++++
>  tests/tracetool/log.c                   |  32 ++++++++
>  tests/tracetool/log.h                   |  57 +++++++++++++
>  tests/tracetool/meson.build             |  25 ++++++
>  tests/tracetool/simple.c                |  61 ++++++++++++++
>  tests/tracetool/simple.h                |  54 ++++++++++++
>  tests/tracetool/syslog.c                |  32 ++++++++
>  tests/tracetool/syslog.h                |  57 +++++++++++++
>  tests/tracetool/trace-events            |   5 ++
>  tests/tracetool/tracetool-test.py       | 105 ++++++++++++++++++++++++
>  tests/tracetool/ust.c                   |  32 ++++++++
>  tests/tracetool/ust.h                   |  55 +++++++++++++
>  tests/tracetool/ust.ust-events-c        |  14 ++++
>  tests/tracetool/ust.ust-events-h        |  56 +++++++++++++
>  25 files changed, 867 insertions(+)
>  create mode 100644 tests/tracetool/dtrace.c
>  create mode 100644 tests/tracetool/dtrace.d
>  create mode 100644 tests/tracetool/dtrace.h
>  create mode 100644 tests/tracetool/dtrace.log-stap
>  create mode 100644 tests/tracetool/dtrace.simpletrace-stap
>  create mode 100644 tests/tracetool/dtrace.stap
>  create mode 100644 tests/tracetool/ftrace.c
>  create mode 100644 tests/tracetool/ftrace.h
>  create mode 100644 tests/tracetool/log.c
>  create mode 100644 tests/tracetool/log.h
>  create mode 100644 tests/tracetool/meson.build
>  create mode 100644 tests/tracetool/simple.c
>  create mode 100644 tests/tracetool/simple.h
>  create mode 100644 tests/tracetool/syslog.c
>  create mode 100644 tests/tracetool/syslog.h
>  create mode 100644 tests/tracetool/trace-events
>  create mode 100755 tests/tracetool/tracetool-test.py
>  create mode 100644 tests/tracetool/ust.c
>  create mode 100644 tests/tracetool/ust.h
>  create mode 100644 tests/tracetool/ust.ust-events-c
>  create mode 100644 tests/tracetool/ust.ust-events-h

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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