ONNX will build googletest from a Git checkout.  Patch CMake to use our
googletest package and enable tests by default.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0aa9fda2..a573170c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,7 +22,7 @@ option(BUILD_ONNX_PYTHON "Build Python binaries" OFF)
 option(ONNX_GEN_PB_TYPE_STUBS "Generate protobuf python type stubs" ON)
 option(ONNX_WERROR "Build with Werror" OFF)
 option(ONNX_COVERAGE "Build with coverage instrumentation" OFF)
-option(ONNX_BUILD_TESTS "Build ONNX C++ APIs Tests" OFF)
+option(ONNX_BUILD_TESTS "Build ONNX C++ APIs Tests" ON)
 option(ONNX_USE_LITE_PROTO "Use lite protobuf instead of full." OFF)
 option(ONNXIFI_ENABLE_EXT "Enable onnxifi extensions." OFF)
 if(NOT DEFINED ONNX_ML)
@@ -82,8 +82,10 @@ if(CMAKE_SYSTEM_NAME STREQUAL "AIX")
 endif()

 if(ONNX_BUILD_TESTS)
-  list(APPEND CMAKE_MODULE_PATH ${ONNX_ROOT}/cmake/external)
-  include(googletest)
+  find_package(GTest REQUIRED)
+  if(NOT GTest_FOUND)
+    message(FATAL_ERROR "cannot find googletest")
+  endif()
 endif()

 if((ONNX_USE_LITE_PROTO AND TARGET protobuf::libprotobuf-lite) OR ((NOT ONNX_USE_LITE_PROTO) AND TARGET protobuf::libprotobuf))
diff --git a/cmake/unittest.cmake b/cmake/unittest.cmake
index e29a93ff..ae146390 100644
--- a/cmake/unittest.cmake
+++ b/cmake/unittest.cmake
@@ -6,8 +6,8 @@ include(${ONNX_ROOT}/cmake/Utils.cmake)

 find_package(Threads)

-set(${UT_NAME}_libs ${googletest_STATIC_LIBRARIES})
-set(${ONNXIFI_TEST_DRIVER}_libs ${googletest_STATIC_LIBRARIES})
+set(${UT_NAME}_libs ${GTEST_LIBRARIES})
+set(${ONNXIFI_TEST_DRIVER}_libs ${GTEST_LIBRARIES})

 list(APPEND ${UT_NAME}_libs onnx)
 list(APPEND ${UT_NAME}_libs onnx_proto)
@@ -31,10 +31,10 @@ function(AddTest)
   list(REMOVE_DUPLICATES _UT_SOURCES)

   add_executable(${_UT_TARGET} ${_UT_SOURCES})
-  add_dependencies(${_UT_TARGET} onnx onnx_proto googletest)
+  add_dependencies(${_UT_TARGET} onnx onnx_proto)

   target_include_directories(${_UT_TARGET}
-                             PUBLIC ${googletest_INCLUDE_DIRS}
+                             PUBLIC ${GTEST_INCLUDE_DIRS}
                                     ${ONNX_INCLUDE_DIRS}
                                     ${PROTOBUF_INCLUDE_DIRS}
                                     ${ONNX_ROOT}
4468b4b846d1104a73007'>svg.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/build/svg.scm?id=745d3a9b44f93af6fa84468b4b846d1104a73007&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-06-01 15:21:28 +0200'>2018-06-01</span></td><td><a href='/guix/commit/gnu/build/svg.scm?id=33d8a871042e73d6b236793d02e5a8287a47ebe4'>bootloader: grub: Use 'with-extensions'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/bootloader/grub.scm (svg-&gt;png): Use 'with-extensions'.  Remove
'add-to-load-path' calls.
* gnu/build/svg.scm: Use (rsvg) and (cairo) the normal way.  Remove
'module-autoload!' calls.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-07-02 22:52:30 +0200'>2017-07-02</span></td><td><a href='/guix/commit/gnu/build/svg.scm?id=1b0f266e40aead09be95a984bd9c6cec3dff397e'>gnu: Switch guile-cairo and dependents to Guile 2.2 again.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://bugs.gnu.org/27551&gt;.
Reported by Leo Famulari &lt;leo@famulari.name&gt;.

This reinstates the following commits:

  e3ddb1e83 * gnu: guile-cairo: Switch to Guile 2.2.
  ae5c6ef39 * gnu: guile-gnome: Update to 2.16.5.
  0fd8013fc * gnu: guile-rsvg: Update to commit 05c6a2fd.
  66b9183c4 * gnu: guile-lib: Switch to Guile 2.2.

and adds the following changes:

* gnu/bootloader/grub.scm (svg-&gt;png): Add 'package-&gt;derivation' call for
GUILE-2.2.  Pass #:guile-for-build to 'gexp-&gt;derivation'.
* gnu/build/svg.scm (svg-&gt;png): Add 'em' and 'ex' to the 'let-values'
form to account for all the values returned by
'rsvg-handle-get-dimensions', which Guile 2.2 does not truncate.
</span></span></td><td>Ludovic Courtès</td></tr>