DPL: add test for exception throwing in Variant (#13735)

Author: ktf

Framework/Core/include/Framework/Variant.h

@@ -355,7 +355,7 @@ class Variant
   T get() const
   {
     if (mType != variant_trait_v<T>) {
-      throw runtime_error("Mismatch between types");
+      throw runtime_error_f("Variant::get: Mismatch between types %d %d.", mType, variant_trait_v<T>);
     }
     return variant_helper<T>::get(&mStore);
   }

Framework/Core/test/test_Variants.cxx

@@ -338,3 +338,15 @@ TEST_CASE("VariantJSONConversionsTest")
     REQUIRE(vstrings[i] == vvstra.get<std::string*>()[i]);
   }
 }
+
+TEST_CASE("VariantThrowing")
+{
+  Variant a("true");
+  REQUIRE_THROWS_AS(a.get<int>(), o2::framework::RuntimeErrorRef);
+  try {
+    a.get<int>();
+  } catch (RuntimeErrorRef& ref) {
+    RuntimeError& error = error_from_ref(ref);
+    REQUIRE(error.what == std::string("Variant::get: Mismatch between types 4 0."));
+  }
+}