The LLDB test suite consists of three different kinds of test:

  • Unit test. These are located under lldb/unittests and are written in C++ using googletest.
  • Integration tests that test the debugger through the SB API. These are located under lldb/packages/Python/lldbsuite and are written in Python using dotest (LLDB’s custom testing framework on top of unittest2).
  • Integration tests that test the debugger through the command line. These are located under lldb/test/Shell and are written in a shell-style format using FileCheck to verify its output.

All three test suites use the LLVM Integrated Tester (lit) as their test driver. The test suites can be run as a whole or separately.

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.


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 LLDB.


On NetBSD you must export LD_LIBRARY_PATH=$PWD/lib in your environment. This is due to lack of the $ORIGIN linker feature.

Running the Full Test Suite

The easiest way to run the LLDB test suite is to use the check-lldb build target.

By default, the check-lldb target builds the test programs with the same compiler that was used to build LLDB. To build the tests with a different compiler, you can set the LLDB_TEST_COMPILER CMake variable.

It is possible to customize the architecture of the test binaries and compiler used by appending -A and -C options respectively to the CMake variable LLDB_TEST_USER_ARGS. For example, to test LLDB against 32-bit binaries built with a custom version of clang, do:

$ 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 Single Test Suite

Each test suite can be run separately, similar to running the whole test suite with check-lldb.

  • Use check-lldb-unit to run just the unit tests.
  • Use check-lldb-api to run just the SB API tests.
  • Use check-lldb-shell to run just the shell tests.

You can run specific subdirectories by appending the directory name to the target. For example, to run all the tests in ObjectFile, you can use the target check-lldb-shell-objectfile. However, because the unit tests and API tests don’t actually live under lldb/test, this convenience is only available for the shell tests.

Running a Single Test

The recommended way to run a single test is by invoking the lit driver with a filter. This ensures that the test is run with the same configuration as when run as part of a test suite.

$ ./bin/llvm-lit -sv tools/lldb/test --filter <test>

Because lit automatically scans a directory for tests, it’s also possible to pass a subdirectory to run a specific subset of the tests.

$ ./bin/llvm-lit -sv tools/lldb/test/Shell/Commands/CommandScriptImmediateOutput

For the SB API tests it is possible to forward arguments to dotest.py by passing --param to lit and setting a value for dotest-args.

$ ./bin/llvm-lit -sv tools/lldb/test --param dotest-args='-C gcc'

Below is an overview of running individual test in the unit and API test suites without going through the lit driver.

Running a Specific Test or Set of Tests: API Tests

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.

For example, to run the test cases defined in TestInferiorCrashing.py, run:

$ ./bin/lldb-dotest -p TestInferiorCrashing.py
$ cd $lldb/test
$ python dotest.py --executable <path-to-lldb> -p TestInferiorCrashing.py ../packages/Python/lldbsuite/test

If the test is not specified by name (e.g. if you leave the -p argument off), all tests in that directory will be executed:

$ ./bin/lldb-dotest functionalities/data-formatter
$ 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 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 see the Remote debugging page.
  2. You must tell the test-suite how to connect to the remote system. This is achieved using the --platform-name, --platform-url and --platform-working-dir parameters to dotest.py. These parameters correspond to the platform select and platform connect LLDB commands. You will usually also need to specify the compiler and architecture for the remote system.

Currently, running the remote test suite is supported only with dotest.py (or dosep.py with a single thread), but we expect this issue to be addressed in the near future.

Debugging Test Failures

On non-Windows platforms, you can use the -d option to dotest.py which will cause the script to wait for a while until a debugger is attached.

Debugging Test Failures on Windows

On Windows, it is strongly recommended to use Python Tools for Visual Studio for debugging test failures. It can seamlessly step between native and managed code, which is very helpful when you need to step through the test itself, and then into the LLDB code that backs the operations the test is performing.

A quick guide to getting started with PTVS is as follows:

  1. Install PTVS
  2. Create a Visual Studio Project for the Python code.
    1. Go to File -> New -> Project -> Python -> From Existing Python Code.
    2. Choose llvm/tools/lldb as the directory containing the Python code.
    3. When asked where to save the .pyproj file, choose the folder llvm/tools/lldb/pyproj. This is a special folder that is ignored by the .gitignore file, since it is not checked in.
  3. Set test/dotest.py as the startup file
  4. Make sure there is a Python Environment installed for your distribution. For example, if you installed Python to C:\Python35, PTVS needs to know that this is the interpreter you want to use for running the test suite.
    1. Go to Tools -> Options -> Python Tools -> Environment Options
    2. Click Add Environment, and enter Python 3.5 Debug for the name. Fill out the values correctly.
  5. Configure the project to use this debug interpreter.
    1. Right click the Project node in Solution Explorer.
    2. In the General tab, Make sure Python 3.5 Debug is the selected Interpreter.
    3. In Debug/Search Paths, enter the path to your ninja/lib/site-packages directory.
    4. In Debug/Environment Variables, enter VCINSTALLDIR=C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\.
    5. If you want to enabled mixed mode debugging, check Enable native code debugging (this slows down debugging, so enable it only on an as-needed basis.)
  6. Set the command line for the test suite to run.
    1. Right click the project in solution explorer and choose the Debug tab.
    2. Enter the arguments to dotest.py.
    3. Example command options:
# Path to debug lldb.exe
--executable D:/src/llvmbuild/ninja/bin/lldb.exe
# Directory to store log files
-s D:/src/llvmbuild/ninja/lldb-test-traces
# If a test crashes, show JIT debugging dialog.
# Path to release clang.exe
-C d:\src\llvmbuild\ninja_release\bin\clang.exe
# Path to the particular test you want to debug.
-p TestPaths.py
# Root of test tree
--arch=i686 --executable D:/src/llvmbuild/ninja/bin/lldb.exe -s D:/src/llvmbuild/ninja/lldb-test-traces -u CXXFLAGS -u CFLAGS --enable-crash-dialog -C d:\src\llvmbuild\ninja_release\bin\clang.exe -p TestPaths.py D:\src\llvm\tools\lldb\packages\Python\lldbsuite\test --no-multiprocess