chore: Rust-C++ cmake and CI integration (#7034)

src/tests/libxrpl/CMakeLists.txt

@@ -43,6 +43,9 @@ set(test_modules
 if(NOT WIN32)
     list(APPEND test_modules net)
 endif()
+if(rust)
+    target_link_libraries(xrpl_tests PRIVATE rs_hello_world_cxxbridge)
+endif()
 
 foreach(module IN LISTS test_modules)
     # Append the module's sources (${module}/*.cpp and ${module}.cpp, if any).
@@ -52,6 +55,12 @@ foreach(module IN LISTS test_modules)
         "${CMAKE_CURRENT_SOURCE_DIR}/${module}/*.cpp"
         "${CMAKE_CURRENT_SOURCE_DIR}/${module}.cpp"
     )
+    if(NOT rust)
+        # Tests of the Rust interop include generated cxxbridge headers, which
+        # do not exist without the crates, so keep them out of the build tree
+        # entirely. They are named `Rust<something>.cpp`.
+        list(FILTER sources EXCLUDE REGEX "/Rust[^/]*\\.cpp$")
+    endif()
     target_sources(xrpl_tests PRIVATE ${sources})
 
     # Expose the module's private headers under their canonical include path.

src/tests/libxrpl/basics/RustInterop.cpp

@@ -0,0 +1,9 @@
+#include <gtest/gtest.h>
+#include <rs_hello_world_cxxbridge/lib.h>
+
+#include <string>
+
+TEST(RustInteropTest, hello_world)
+{
+    EXPECT_EQ(std::string(rs::hello_world::hello_world()), "hello_world");
+}