Add assertion to process method (#1453)

Also adjust clangd so it doesn't bother us with header files about `expected`.

.clangd

@@ -5,4 +5,6 @@ Diagnostics:
   UnusedIncludes: Strict
   MissingIncludes: Strict
   Includes:
-    IgnoreHeader: ".*/(detail|impl)/.*"
+    IgnoreHeader:
+      - ".*/(detail|impl)/.*"
+      - ".*expected.*"

src/rpc/handlers/Feature.cpp

@@ -25,6 +25,7 @@
 #include "rpc/common/Specs.hpp"
 #include "rpc/common/Types.hpp"
 #include "rpc/common/Validators.hpp"
+#include "util/Assert.hpp"
 
 #include <boost/json/conversion.hpp>
 #include <boost/json/value.hpp>
@@ -40,6 +41,7 @@ FeatureHandler::process([[maybe_unused]] FeatureHandler::Input input, [[maybe_un
 {
     // For now this handler only fires when "vetoed" is set in the request.
     // This always leads to a `notSupported` error as we don't want anyone to be able to
+    ASSERT(false, "FeatureHandler::process is not implemented.");
     return Output{};
 }
 

tests/unit/rpc/handlers/FeatureTests.cpp

@@ -23,6 +23,7 @@
 #include "rpc/handlers/Feature.hpp"
 #include "util/Fixtures.hpp"
 
+#include <boost/asio/io_context.hpp>
 #include <boost/json/parse.hpp>
 #include <gtest/gtest.h>
 
@@ -46,3 +47,13 @@ TEST_F(RPCFeatureHandlerTest, AlwaysNoPermissionForVetoed)
         );
     });
 }
+
+TEST(RPCFeatureHandlerDeathTest, ProcessCausesDeath)
+{
+    FeatureHandler handler{};
+    boost::asio::io_context ioContext;
+    boost::asio::spawn(ioContext, [&](auto yield) {
+        EXPECT_DEATH(handler.process(FeatureHandler::Input{"foo"}, Context{yield}), "");
+    });
+    ioContext.run();
+}