Add dependencies locally

deps/json/tests/cmake_fetch_content/CMakeLists.txt

@@ -0,0 +1,20 @@
+if (${CMAKE_VERSION} VERSION_GREATER "3.11.0")
+  add_test(NAME cmake_fetch_content_configure
+    COMMAND ${CMAKE_COMMAND}
+    -G "${CMAKE_GENERATOR}"
+    -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+    -Dnlohmann_json_source=${PROJECT_SOURCE_DIR}
+    ${CMAKE_CURRENT_SOURCE_DIR}/project
+  )
+  add_test(NAME cmake_fetch_content_build
+    COMMAND ${CMAKE_COMMAND} --build .
+  )
+  set_tests_properties(cmake_fetch_content_configure PROPERTIES
+    FIXTURES_SETUP cmake_fetch_content
+    LABELS "git_required;not_reproducible"
+  )
+  set_tests_properties(cmake_fetch_content_build PROPERTIES
+    FIXTURES_REQUIRED cmake_fetch_content
+    LABELS "git_required;not_reproducible"
+  )
+endif()

deps/json/tests/cmake_fetch_content/project/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.11)
+
+project(DummyImport CXX)
+
+include(FetchContent)
+
+get_filename_component(GIT_REPOSITORY_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../../.. ABSOLUTE)
+FetchContent_Declare(json GIT_REPOSITORY ${GIT_REPOSITORY_DIRECTORY} GIT_TAG HEAD)
+
+FetchContent_GetProperties(json)
+if(NOT json_POPULATED)
+  FetchContent_Populate(json)
+  add_subdirectory(${json_SOURCE_DIR} ${json_BINARY_DIR} EXCLUDE_FROM_ALL)
+endif()
+
+add_executable(with_namespace_target main.cpp)
+target_link_libraries(with_namespace_target nlohmann_json::nlohmann_json)
+
+add_executable(without_namespace_target main.cpp)
+target_link_libraries(without_namespace_target nlohmann_json)

deps/json/tests/cmake_fetch_content/project/main.cpp

@@ -0,0 +1,16 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.11.2
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2022 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include <nlohmann/json.hpp>
+
+int main(int argc, char** argv)
+{
+    nlohmann::json j;
+
+    return 0;
+}