cmake: tf-psa-crypto: Add cmake_subproject test program

The empty framework directory is temporary. It will be
removed when TF-PSA-Crypto uses its framework submodule.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>

tf-psa-crypto/programs/test/cmake_subproject/.gitignore

@@ -0,0 +1,3 @@
+build
+Makefile
+cmake_subproject

tf-psa-crypto/programs/test/cmake_subproject/CMakeLists.txt

@@ -0,0 +1,18 @@
+cmake_minimum_required(VERSION 3.5.1)
+
+# Test the target renaming support by adding a prefix to the targets built
+set(TF_PSA_CRYPTO_TARGET_PREFIX subproject_test_)
+
+# We use the parent TF-PSA-Crypto directory as the TF_PSA_CRYPTO_DIR for this
+# test. Other projects that use TF-PSA-Crypto as a subproject are likely to
+# add by their own relative paths.
+set(TF_PSA_CRYPTO_DIR ../../../)
+
+# Add TF-PSA-Crypto as a subdirectory.
+add_subdirectory(${TF_PSA_CRYPTO_DIR} build)
+
+# Link against all the TF-PSA-Crypto library. Verifies that the target has been
+# created using the specified prefix
+
+add_executable(cmake_subproject cmake_subproject.c)
+target_link_libraries(cmake_subproject subproject_test_mbedcrypto ${CMAKE_THREAD_LIBS_INIT})

tf-psa-crypto/programs/test/cmake_subproject/cmake_subproject.c

@@ -0,0 +1,19 @@
+/*
+ *  Simple program to test that CMake builds with TF-PSA-Crypto as a
+ *  subdirectory work correctly.
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include <psa/crypto.h>
+
+/* The main reason to build this is for testing the CMake build, so the program
+ * doesn't need to do very much. It calls a PSA cryptography API to ensure
+ * linkage works, but that is all. */
+int main()
+{
+    psa_crypto_init();
+
+    return 0;
+}

tf-psa-crypto/tests/scripts/components-build-system.sh

@@ -22,3 +22,12 @@ component_test_tf_psa_crypto_cmake_out_of_source () {
     cd "$TF_PSA_CRYPTO_ROOT_DIR"
     rm -rf "$OUT_OF_SOURCE_DIR"
 }
+
+component_test_tf_psa_crypto_cmake_as_subdirectory () {
+    msg "build: cmake 'as-subdirectory' build"
+    cd programs/test/cmake_subproject
+    # Note: Explicitly generate files as these are turned off in releases
+    cmake -D GEN_FILES=ON .
+    make
+    ./cmake_subproject
+}