Move C++ generated code test to cxx's integration test
diff --git a/tests/cxx_gen.rs b/tests/cxx_gen.rs
new file mode 100644
index 0000000..b5ff106
--- /dev/null
+++ b/tests/cxx_gen.rs
@@ -0,0 +1,31 @@
+use cxx_gen::{generate_header_and_cc, Opt};
+
+const CPP_EXAMPLE: &str = r#"
+    #[cxx::bridge]
+    mod ffi {
+        extern "C" {
+            pub fn do_cpp_thing(foo: &str);
+        }
+    }
+"#;
+
+#[test]
+fn test_cpp() {
+    let opt = Opt::default();
+    let source = CPP_EXAMPLE.parse().unwrap();
+    let output = generate_header_and_cc(source, &opt).unwrap();
+    let output = std::str::from_utf8(&output.implementation).unwrap();
+    // To avoid continual breakage we won't test every byte.
+    // Let's look for the major features.
+    assert!(output.contains("void cxxbridge04$do_cpp_thing(::rust::Str::Repr foo)"));
+}
+
+#[test]
+fn test_annotation() {
+    let mut opt = Opt::default();
+    opt.cxx_impl_annotations = Some("ANNOTATION".to_owned());
+    let source = CPP_EXAMPLE.parse().unwrap();
+    let output = generate_header_and_cc(source, &opt).unwrap();
+    let output = std::str::from_utf8(&output.implementation).unwrap();
+    assert!(output.contains("ANNOTATION void cxxbridge04$do_cpp_thing(::rust::Str::Repr foo)"));
+}