From 59f6e93ed1b57c39efdd39156913baefef6d8dd3 Mon Sep 17 00:00:00 2001
From: doodspav <doodspav@gmail.com>
Date: Sat, 18 Mar 2023 10:46:51 +0000
Subject: [PATCH] GHI #13 Fix Windows PATH issues for tests

Signed-off-by: doodspav <doodspav@gmail.com>
---
 test/CMakeLists.txt                      | 34 ++++++++++++++++++++++++
 test/cmake/OptionVariables.cmake         | 13 +++++++++
 test/cmake/WindowsDependenciesPath.cmake | 30 +++++++++++++++++++++
 3 files changed, 77 insertions(+)
 create mode 100644 test/cmake/OptionVariables.cmake
 create mode 100644 test/cmake/WindowsDependenciesPath.cmake

diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index ba3f3131f..a2f8aa142 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -7,6 +7,8 @@ project(
     LANGUAGES CXX
 )
 
+include(cmake/OptionVariables.cmake)
+
 
 # ---- Dependencies ----
 
@@ -17,6 +19,8 @@ if(PROJECT_IS_TOP_LEVEL)
     enable_testing()
 endif()
 
+# for Windows: prevent overriding the parent project's compiler/linker settings
+set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
 find_package(GTest REQUIRED)
 include(GoogleTest)
 
@@ -45,3 +49,33 @@ gtest_add_tests(
     TARGET patomic_test
     TEST_LIST patomic_test_TESTS
 )
+
+
+# ---- Windows Path Issues ----
+
+include(cmake/WindowsDependenciesPath.cmake)
+windows_deps_path(
+    deps_path
+    patomic::patomic
+    GTest::gtest_main
+)
+
+# check we're on Windows, and we have SHARED_LIBRARY dependencies
+if(NOT deps_path STREQUAL "" AND CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
+
+    # set environment variable for each test ctest works automatically
+    if(patomic_test_SET_CTEST_PATH_ENV_WINDOWS)
+        foreach(test IN LISTS patomic_test_TESTS)
+            set_property(
+                TEST "${test}"
+                PROPERTY ENVIRONMENT "PATH=${deps_path}"
+            )
+        endforeach()
+    endif()
+
+    # create file with PATH contents for when not running tests through CMake
+    file(GENERATE
+        OUTPUT "${PROJECT_BINARY_DIR}/windows_dependencies_path.txt"
+        CONTENT "${deps_path}"
+    )
+endif()
diff --git a/test/cmake/OptionVariables.cmake b/test/cmake/OptionVariables.cmake
new file mode 100644
index 000000000..8a57b9f5f
--- /dev/null
+++ b/test/cmake/OptionVariables.cmake
@@ -0,0 +1,13 @@
+# ---- Windows Tests Path ----
+
+# By default we set PATH for tests run with CTest on Windows in order to prevent
+# linker errors.
+# Due to limitations in CMake, we can only completely override the PATH, rather
+# than prepend to it.
+# This gives users the option to disable this behaviour.
+option(
+    patomic_test_SET_CTEST_PATH_ENV_WINDOWS
+    "Set PATH environment variable for tests when run using CTest on Windows"
+    ON
+)
+mark_as_advanced(patomic_test_SET_CTEST_PATH_ENV_WINDOWS)
diff --git a/test/cmake/WindowsDependenciesPath.cmake b/test/cmake/WindowsDependenciesPath.cmake
new file mode 100644
index 000000000..bfe1b8f78
--- /dev/null
+++ b/test/cmake/WindowsDependenciesPath.cmake
@@ -0,0 +1,30 @@
+# ---- Windows Path Prefix ----
+
+# Windows doesn't support rpath, so when linking dynamically the libraries need
+# to either be in the same directory or on PATH.
+# This function sets a variable to a GENERATOR string that may be prepended to
+# path in order to find linked dependencies
+# See: https://docs.microsoft.com/en-us/windows/win32/dlls/dynamic-link-library-search-order
+# Usage: windows_deps_path(<variable> <link-target>...)
+function(windows_deps_path VAR)
+    if(NOT CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
+        set(${VAR} "" PARENT_SCOPE)
+        return()
+    endif()
+
+    set(path "")
+    set(glue "")
+    foreach(target IN LISTS ARGN)
+        get_target_property(type "${target}" TYPE)
+        if(type STREQUAL "SHARED_LIBRARY")
+            set(path "${path}${glue}$<TARGET_FILE_DIR:${target}>")
+            set(glue "\;")  # backslash is important
+        endif()
+    endforeach()
+
+    if(NOT path STREQUAL "")
+        set(${VAR} "${path}" PARENT_SCOPE)
+    else()
+        set(${VAR} "" PARENT_SCOPE)
+    endif()
+endfunction()