1 files changed, 58 insertions, 0 deletions
diff --git a/docs/devel/qtest.rst b/docs/devel/qtest.rst
new file mode 100644
index 0000000000..86dec84a0b
--- /dev/null
+++ b/docs/devel/qtest.rst
@@ -0,0 +1,58 @@
+========================================
+QTest Device Emulation Testing Framework
+========================================
+
+QTest is a device emulation testing framework.  It can be very useful to test
+device models; it could also control certain aspects of QEMU (such as virtual
+clock stepping), with a special purpose "qtest" protocol.  Refer to the
+documentation in ``qtest.c`` for more details of the protocol.
+
+QTest cases can be executed with
+
+.. code::
+
+   make check-qtest
+
+The QTest library is implemented by ``tests/qtest/libqtest.c`` and the API is
+defined in ``tests/qtest/libqtest.h``.
+
+Consider adding a new QTest case when you are introducing a new virtual
+hardware, or extending one if you are adding functionalities to an existing
+virtual device.
+
+On top of libqtest, a higher level library, ``libqos``, was created to
+encapsulate common tasks of device drivers, such as memory management and
+communicating with system buses or devices. Many virtual device tests use
+libqos instead of directly calling into libqtest.
+
+Steps to add a new QTest case are:
+
+1. Create a new source file for the test. (More than one file can be added as
+   necessary.) For example, ``tests/qtest/foo-test.c``.
+
+2. Write the test code with the glib and libqtest/libqos API. See also existing
+   tests and the library headers for reference.
+
+3. Register the new test in ``tests/qtest/Makefile.include``. Add the test
+   executable name to an appropriate ``check-qtest-*-y`` variable. For example:
+
+   ``check-qtest-generic-y = tests/qtest/foo-test$(EXESUF)``
+
+4. Add object dependencies of the executable in the Makefile, including the
+   test source file(s) and other interesting objects. For example:
+
+   ``tests/qtest/foo-test$(EXESUF): tests/qtest/foo-test.o $(libqos-obj-y)``
+
+Debugging a QTest failure is slightly harder than the unit test because the
+tests look up QEMU program names in the environment variables, such as
+``QTEST_QEMU_BINARY`` and ``QTEST_QEMU_IMG``, and also because it is not easy
+to attach gdb to the QEMU process spawned from the test. But manual invoking
+and using gdb on the test is still simple to do: find out the actual command
+from the output of
+
+.. code::
+
+  make check-qtest V=1
+
+which you can run manually.
+