Initialize CHIP stack before running app tests

src/app/tests/AppTestContext.cpp

@@ -41,6 +41,7 @@ namespace Test {
 CHIP_ERROR AppContext::Init()
 {
     ReturnErrorOnFailure(Super::Init());
+    ReturnErrorOnFailure(chip::DeviceLayer::PlatformMgr().InitChipStack());
     ReturnErrorOnFailure(chip::app::InteractionModelEngine::GetInstance()->Init(&GetExchangeManager(), &GetFabricTable(),
                                                                                 app::reporting::GetDefaultReportScheduler()));
 
@@ -57,6 +58,7 @@ void AppContext::Shutdown()
     Access::ResetAccessControlToDefault();
 
     chip::app::InteractionModelEngine::GetInstance()->Shutdown();
+    chip::DeviceLayer::PlatformMgr().Shutdown();
     Super::Shutdown();
 }
 

src/crypto/CHIPCryptoPALmbedTLS.cpp

@@ -448,9 +448,25 @@ CHIP_ERROR add_entropy_source(entropy_source fn_source, void * p_source, size_t
     EntropyContext * const entropy_ctxt = get_entropy_context();
     VerifyOrReturnError(entropy_ctxt != nullptr, CHIP_ERROR_INTERNAL);
 
+#if (MBEDTLS_ALLOW_PRIVATE_ACCESS + 0) == 1
+    // NOTE: This check is needed mostly for unit tests, where we might run
+    //       init/shutdown multiple times, however, mbedTLS does not provide
+    //       API to remove entropy source from the pool.
+    for (int i = 0; i < entropy_ctxt->mEntropy.source_count; i++)
+    {
+        const auto & source = entropy_ctxt->mEntropy.source[i];
+        if (source.f_source == fn_source && source.p_source == p_source && source.threshold == threshold &&
+            source.strong == MBEDTLS_ENTROPY_SOURCE_STRONG)
+        {
+            return CHIP_NO_ERROR;
+        }
+    }
+#endif
+
     const int result =
         mbedtls_entropy_add_source(&entropy_ctxt->mEntropy, fn_source, p_source, threshold, MBEDTLS_ENTROPY_SOURCE_STRONG);
     VerifyOrReturnError(result == 0, CHIP_ERROR_INTERNAL);
+
     return CHIP_NO_ERROR;
 }
 

src/test_driver/nrfconnect/CMakeLists.txt

@@ -44,6 +44,11 @@ set(CHIP_CFLAGS
     -I${CMAKE_CURRENT_SOURCE_DIR}/main/include
 )
 
+# Allow access to private members of mbedtls structures, which is needed by CHIP
+# crypto PAL implementation to make the add_entropy_source() independent for the
+# purpose of running unit tests.
+set(CHIP_CFLAGS ${CHIP_CFLAGS} -DMBEDTLS_ALLOW_PRIVATE_ACCESS=1)
+
 # Load NCS/Zephyr build system
 list(APPEND ZEPHYR_EXTRA_MODULES ${CHIP_ROOT}/config/nrfconnect/chip-module)
 find_package(Zephyr HINTS $ENV{ZEPHYR_BASE})