build-system: add coverage-report target

This will build a coverage report under the current directory in
reports/coverage. At the users option a report can be generated by
directly invoking something like:

  make foo/bar/coverage-report.html

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/docs/devel/testing.rst b/docs/devel/testing.rst
index 7f04ca1..5e19cd5 100644
--- a/docs/devel/testing.rst
+++ b/docs/devel/testing.rst
@@ -166,9 +166,14 @@ If you want to gather coverage information on a single test the ``make
 clean-coverage`` target can be used to delete any existing coverage
 information before running a single test.
 
-Reports can be obtained by running ``gcov`` command
-on the output files under ``$build_dir/tests/``, please read the
-``gcov`` documentation for more information.
+You can generate a HTML coverage report by executing ``make
+coverage-report`` which will create
+./reports/coverage/coverage-report.html. If you want to create it
+elsewhere simply execute ``make /foo/bar/baz/coverage-report.html``.
+
+Further analysis can be conducted by running the ``gcov`` command
+directly on the various .gcda output files. Please read the ``gcov``
+documentation for more information.
 
 QEMU iotests
 ============