IVGCVSW-4915 Improving messages around SAMPLE_DYNAMIC_BACKEND_ENABLED

* If SAMPLE_DYNAMIC_BACKEND_ENABLED is enabled but DYNAMIC_BACKEND_PATHS
  is not set then the user gets failing tests cases with no clear idea
  what has gone wrong. Explicitly failing when DYNAMIC_BACKEND_PATHS has
  not been set.
* Adding an FAQ entry describing how the user can get confused by our
  documented usage of CMake.

Signed-off-by: Colm Donelan <Colm.Donelan@arm.com>
Change-Id: Ic11e14a971f53a6454962354ff728365ccc9de6d

1 files changed, 12 insertions, 2 deletions

diff --git a/src/backends/backendsCommon/test/DynamicBackendTests.hpp b/src/backends/backendsCommon/test/DynamicBackendTests.hpp
index 6371e53250..16c2f0db7a 100644
--- a/src/backends/backendsCommon/test/DynamicBackendTests.hpp
+++ b/src/backends/backendsCommon/test/DynamicBackendTests.hpp
@@ -1439,11 +1439,15 @@ void CreateReferenceDynamicBackendTestImpl()
 void CreateSampleDynamicBackendTestImpl()
 {
     using namespace armnn;
-
     // Using the path override in CreationOptions to load the reference dynamic backend
     IRuntime::CreationOptions creationOptions;
-    IRuntimePtr runtime = IRuntime::Create(creationOptions);
+    // If m_DynamicBackendsPath is an empty string then we know this test will fail.
+    if(creationOptions.m_DynamicBackendsPath.empty())
+    {
+        BOOST_FAIL("No dynamic backends paths have been set. Ensure DYNAMIC_BACKEND_PATHS is set at compile time.");
+    }
 
+    IRuntimePtr runtime = IRuntime::Create(creationOptions);
     const BackendRegistry& backendRegistry = BackendRegistryInstance();
     BOOST_TEST(backendRegistry.Size() >= 1);
 
@@ -1506,6 +1510,12 @@ void SampleDynamicBackendEndToEndTestImpl()
     using namespace boost::filesystem;
     // Create runtime in which test will run
     IRuntime::CreationOptions options;
+    // If m_DynamicBackendsPath is an empty string then we know this test will fail.
+    if(options.m_DynamicBackendsPath.empty())
+    {
+        BOOST_FAIL("No dynamic backends paths have been set. Ensure DYNAMIC_BACKEND_PATHS is set at compile time.");
+    }
+
     IRuntimePtr runtime(IRuntime::Create(options));
 
     // Builds up the structure of the network.