documentation: update test.rst

[lawrence_danna]

Summary

The testing documentation appears to be from an era when the only
kind of tests were the lldbsuite python tests. This patch adds
a short description of the unittests and LIT tests and how to run them.

[JDevlieghere]

lldb/docs/resources/test.rst

126

Another alternative worth mentioning is using --filter. You can point lit to the root of the lit tests and run one or more tests that match the given substring.

> ./bin/llvm-lit -sv tools/lldb/lit --filter CommandScriptImmediateOutput

[labath]

This should have been done a long time ago, thanks for taking care of that.

[lawrence_danna]

added note about passing --filter to lit

lldb/docs/resources/test.rst

 Testing
 =======
 
-The LLDB test suite consists of Python scripts located under the test
-directory. Each script contains a number of test cases and is usually
-accompanied by a C (C++, ObjC, etc.) source file. Each test first compiles the
-source file and then uses LLDB to debug the resulting executable. The tests
-verify both the LLDB command line interface and the scripting API.
+The LLDB test suite consists of three different kinds of test:
+
+* Python scripts located under ``lldb/packages/Python/lldbsuite``.
+  These are written using python's unittest2 testing framework.
+
+* Unit tests, located under ``lldb/unittests``.   These are written in C++,
+  using googletest.
+
+* LIT tests, located under ``lldb/lit``.  These use the LLVM Integrated Tester.
+
+Many of the tests are accompanied by a C (C++, ObjC, etc.) source file. Each test
+first compiles the source file and then uses LLDB to debug the resulting executable.
+
+The tests verify both the LLDB command line interface and the scripting API.
 
 .. contents::
    :local:
 
 .. note::
 
    On Windows any invocations of python should be replaced with python_d, the
    debug interpreter, when running the test suite against a debug version of
::
 
    > cmake -DLLDB_TEST_USER_ARGS="-A i386 -C /path/to/custom/clang" -G Ninja
    > ninja check-lldb
 
 Note that multiple ``-A`` and ``-C`` flags can be specified to
 ``LLDB_TEST_USER_ARGS``.
 
 
-Running a Specific Test or Set of Tests
----------------------------------------
+Running a Specific Test or Set of Tests: Python
+-----------------------------------------------
 
 In addition to running all the LLDB test suites with the ``check-lldb`` CMake
 target above, it is possible to run individual LLDB tests. If you have a CMake
 build you can use the ``lldb-dotest`` binary, which is a wrapper around
 ``dotest.py`` that passes all the arguments configured by CMake. Alternatively,
 you can use ``dotest.py`` directly, if you want to run a test one-off with a
 different configuration.
 
::
    > python dotest.py --executable <path-to-lldb> functionalities/data-formatter
 
 Many more options that are available. To see a list of all of them, run:
 
 ::
 
    > python dotest.py -h
 
+
+Running a Specific Test or Set of Tests: Unit Tests
+---------------------------------------------------
+
+The unit tests are simple executables, located in the build directory under ``tools/lldb/unittests``.
+
+To run them, just run the test binary, for example, to run all the Host tests:
+
+::
+
+   > ./tools/lldb/unittests/Host/HostTests
+
+
+To run a specific test, pass a filter, for example:
+
+::
+
+   > ./tools/lldb/unittests/Host/HostTests --gtest_filter=SocketTest.DomainListenConnectAccept
+
+
+Running a Specific Test or Set of Tests: LIT
+--------------------------------------------
+
+LIT automatically scans a directory for tests.   To run a subset of the LIT tests, pass it a
+subdirectory, for example:
+
+::
+
+   > ./bin/llvm-lit -sv tools/lldb/lit/Commands/CommandScriptImmediateOutput
+
+
 Running the Test Suite Remotely
 -------------------------------
 
 Running the test-suite remotely is similar to the process of running a local
 test suite, but there are two things to have in mind:
 
 1. You must have the lldb-server running on the remote system, ready to accept
    multiple connections. For more information on how to setup remote debugging