From efa18a621917dc6c38f453825cadc76eb793a73c Mon Sep 17 00:00:00 2001
From: Blaine Bublitz <blaine@aztecprotocol.com>
Date: Fri, 17 Feb 2023 08:24:56 -0700
Subject: [PATCH] feat: Utilize globally installed gtest if available (#151)

---
 cpp/cmake/gtest.cmake  | 56 +++++++++++++++++++++++++-----------------
 cpp/cmake/module.cmake |  6 ++---
 2 files changed, 36 insertions(+), 26 deletions(-)

diff --git a/cpp/cmake/gtest.cmake b/cpp/cmake/gtest.cmake
index 96e88741e9..19a7783153 100644
--- a/cpp/cmake/gtest.cmake
+++ b/cpp/cmake/gtest.cmake
@@ -3,38 +3,48 @@ if(TESTING)
     include(FetchContent)
 
     FetchContent_Declare(
-        googletest
+        GTest
         GIT_REPOSITORY https://github.com/google/googletest.git
         # Version 1.12.1 is not compatible with WASI-SDK 12
-        GIT_TAG release-1.10.0 
+        GIT_TAG release-1.10.0
+        FIND_PACKAGE_ARGS
     )
 
-    FetchContent_GetProperties(googletest)
-    if(NOT googletest_POPULATED)
-        FetchContent_Populate(googletest)
-        add_subdirectory(${googletest_SOURCE_DIR} ${googletest_BINARY_DIR} EXCLUDE_FROM_ALL)
-    endif()
+    set(BUILD_GMOCK OFF CACHE BOOL "Build with gMock disabled")
 
-    # Disable all warning when compiling gtest
-    target_compile_options(
-        gtest
-        PRIVATE
-        -w
-    )
+    FetchContent_MakeAvailable(GTest)
 
-    if(WASM)
-        target_compile_definitions(
+    if (NOT GTest_FOUND)
+        # FetchContent_MakeAvailable calls FetchContent_Populate if `find_package` is unsuccessful
+        # so these variables will be available if we reach this case
+        set_property(DIRECTORY ${gtest_SOURCE_DIR} PROPERTY EXCLUDE_FROM_ALL)
+        set_property(DIRECTORY ${gtest_BINARY_DIR} PROPERTY EXCLUDE_FROM_ALL)
+
+        # Disable all warning when compiling gtest
+        target_compile_options(
             gtest
             PRIVATE
-            -DGTEST_HAS_EXCEPTIONS=0
-            -DGTEST_HAS_STREAM_REDIRECTION=0)
-    endif()
+            -w
+        )
 
-    mark_as_advanced(
-        BUILD_GMOCK BUILD_GTEST BUILD_SHARED_LIBS
-        gmock_build_tests gtest_build_samples gtest_build_tests
-        gtest_disable_pthreads gtest_force_shared_crt gtest_hide_internal_symbols
-    )
+        if(WASM)
+            target_compile_definitions(
+                gtest
+                PRIVATE
+                -DGTEST_HAS_EXCEPTIONS=0
+                -DGTEST_HAS_STREAM_REDIRECTION=0
+            )
+        endif()
+
+        mark_as_advanced(
+            BUILD_GMOCK BUILD_GTEST BUILD_SHARED_LIBS
+            gmock_build_tests gtest_build_samples gtest_build_tests
+            gtest_disable_pthreads gtest_force_shared_crt gtest_hide_internal_symbols
+        )
+
+        add_library(GTest::gtest ALIAS gtest)
+        add_library(GTest::gtest_main ALIAS gtest_main)
+    endif()
 
     enable_testing()
 endif()
diff --git a/cpp/cmake/module.cmake b/cpp/cmake/module.cmake
index 9ff808dd3f..4bb7f526ba 100644
--- a/cpp/cmake/module.cmake
+++ b/cpp/cmake/module.cmake
@@ -54,7 +54,7 @@ function(barretenberg_module MODULE_NAME)
         target_link_libraries(
             ${MODULE_NAME}_test_objects
             PRIVATE
-            gtest
+            GTest::gtest
             ${TBB_IMPORTED_TARGETS}
         )
 
@@ -94,8 +94,8 @@ function(barretenberg_module MODULE_NAME)
             PRIVATE
             ${MODULE_LINK_NAME}
             ${ARGN}
-            gtest
-            gtest_main
+            GTest::gtest
+            GTest::gtest_main
             ${TBB_IMPORTED_TARGETS}
         )