create FindXXX.cmake modules for added CPM packages (#112)

* create FindXXX.cmake modules for added CPM packages

* don't use list(PREPEND) as it unsupported on older CMake versions

* use CMAKE_BINARY_DIR

* ensure CPM.cmake is initialized only once

* import CPM.cmake in modules

test/unit/modules.cmake

@@ -0,0 +1,30 @@
+
+include(CMakePackageConfigHelpers)
+include(${CPM_PATH}/testing.cmake)
+
+set(TEST_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR}/modules)
+
+function(initProjectWithDependency TEST_DEPENDENCY_NAME)
+  configure_package_config_file(
+    "${CMAKE_CURRENT_LIST_DIR}/test_project/CMakeLists.txt.in"
+    "${CMAKE_CURRENT_LIST_DIR}/test_project/CMakeLists.txt"
+    INSTALL_DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/junk
+  )
+
+  execute_process(
+    COMMAND 
+    ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/test_project" "-B${TEST_BUILD_DIR}"
+    RESULT_VARIABLE ret
+  )
+
+  ASSERT_EQUAL(${ret} "0")
+endfunction()
+
+initProjectWithDependency(A)
+ASSERT_EXISTS(${TEST_BUILD_DIR}/CPM_modules)
+ASSERT_EXISTS(${TEST_BUILD_DIR}/CPM_modules/FindA.cmake)
+ASSERT_NOT_EXISTS(${TEST_BUILD_DIR}/CPM_modules/FindB.cmake)
+
+initProjectWithDependency(B)
+ASSERT_NOT_EXISTS(${TEST_BUILD_DIR}/CPM_modules/FindA.cmake)
+ASSERT_EXISTS(${TEST_BUILD_DIR}/CPM_modules/FindB.cmake)

test/unit/source_dir.cmake

@@ -4,15 +4,17 @@ include(${CPM_PATH}/testing.cmake)
 
 set(TEST_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR}/source_dir)
 
+set(TEST_DEPENDENCY_NAME Dependency)
+
 configure_package_config_file(
-  "${CMAKE_CURRENT_LIST_DIR}/source_dir/CMakeLists.txt.in"
-  "${CMAKE_CURRENT_LIST_DIR}/source_dir/CMakeLists.txt"
+  "${CMAKE_CURRENT_LIST_DIR}/test_project/CMakeLists.txt.in"
+  "${CMAKE_CURRENT_LIST_DIR}/test_project/CMakeLists.txt"
   INSTALL_DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/junk
 )
 
 execute_process(
   COMMAND 
-  ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/source_dir" "-B${TEST_BUILD_DIR}"
+  ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/test_project" "-B${TEST_BUILD_DIR}"
   RESULT_VARIABLE ret
 )
 

test/unit/test_project/CMakeLists.txt.in

@@ -11,10 +11,16 @@ option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)
 include(@CPM_PATH@/CPM.cmake)
 
 CPMAddPackage(
-  NAME Dependency
+  NAME @TEST_DEPENDENCY_NAME@
   SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/dependency
 )
 
+# ---- check if generated modules override find_package ----
+
+if (@test_check_find_package@)
+  find_package(@TEST_DEPENDENCY_NAME@ REQUIRED)
+endif()
+
 # ---- Call dependency method to validate correct addition of directory ----
 
 dependency_function()