Optional find dependency in installed cmake config. (#7099)

* Find dependency only when xgboost is built as static library.
* Resolve msvc warning.
* Add test for linking shared library.

tests/cpp/CMakeLists.txt

@@ -18,28 +18,12 @@ if (NOT PLUGIN_UPDATER_ONEAPI)
   list(REMOVE_ITEM TEST_SOURCES ${ONEAPI_TEST_SOURCES})
 endif (NOT PLUGIN_UPDATER_ONEAPI)
 
-add_executable(testxgboost ${TEST_SOURCES}
-  ${xgboost_SOURCE_DIR}/plugin/example/custom_obj.cc)
-target_link_libraries(testxgboost PRIVATE objxgboost)
-
-if (USE_CUDA)
-  xgboost_set_cuda_flags(testxgboost)
+target_sources(testxgboost PRIVATE ${TEST_SOURCES} ${xgboost_SOURCE_DIR}/plugin/example/custom_obj.cc)
 
+if (USE_CUDA AND PLUGIN_RMM)
   find_package(CUDA)
   target_include_directories(testxgboost PRIVATE ${CUDA_INCLUDE_DIRS})
-endif (USE_CUDA)
-
-if (MSVC)
-  target_compile_options(testxgboost PRIVATE
-    $<$<NOT:$<COMPILE_LANGUAGE:CUDA>>:/utf-8>
-    -D_CRT_SECURE_NO_WARNINGS
-    -D_CRT_SECURE_NO_DEPRECATE
-  )
-endif (MSVC)
-if (ENABLE_ALL_WARNINGS)
-  target_compile_options(testxgboost PUBLIC
-    $<IF:$<COMPILE_LANGUAGE:CUDA>,-Xcompiler=-Wall -Xcompiler=-Wextra,-Wall -Wextra>)
-endif (ENABLE_ALL_WARNINGS)
+endif (USE_CUDA AND PLUGIN_RMM)
 
 target_include_directories(testxgboost
   PRIVATE
@@ -47,10 +31,6 @@ target_include_directories(testxgboost
   ${xgboost_SOURCE_DIR}/include
   ${xgboost_SOURCE_DIR}/dmlc-core/include
   ${xgboost_SOURCE_DIR}/rabit/include)
-set_target_properties(
-  testxgboost PROPERTIES
-  CXX_STANDARD 14
-  CXX_STANDARD_REQUIRED ON)
 target_link_libraries(testxgboost
   PRIVATE
   ${GTEST_LIBRARIES})

tests/cpp/common/test_io.cc

@@ -11,6 +11,15 @@
 
 namespace xgboost {
 namespace common {
+TEST(MemoryFixSizeBuffer, Seek) {
+  size_t constexpr kSize { 64 };
+  std::vector<int32_t> memory( kSize );
+  rabit::utils::MemoryFixSizeBuffer buf(memory.data(), memory.size());
+  buf.Seek(rabit::utils::MemoryFixSizeBuffer::kSeekEnd);
+  size_t end = buf.Tell();
+  ASSERT_EQ(end, kSize);
+}
+
 TEST(IO, FileExtension) {
   std::string filename {u8"model.json"};
   auto ext = FileExtension(filename);

tests/cpp/rabit/test_io.cc

@@ -1,18 +0,0 @@
-/*!
- *  Copyright (c) 2019 by Contributors
- */
-#include <gtest/gtest.h>
-#include <rabit/internal/io.h>
-
-#include <vector>
-
-namespace rabit {
-TEST(MemoryFixSizeBuffer, Seek) {
-  size_t constexpr kSize { 64 };
-  std::vector<int32_t> memory( kSize );
-  utils::MemoryFixSizeBuffer buf(memory.data(), memory.size());
-  buf.Seek(utils::MemoryFixSizeBuffer::kSeekEnd);
-  size_t end = buf.Tell();
-  ASSERT_EQ(end, kSize);
-}
-}  // namespace rabit