diff --git a/test/server/Test.interface.yaml b/test/server/Test.interface.yaml
index ac36b84..30df1f9 100644
--- a/test/server/Test.interface.yaml
+++ b/test/server/Test.interface.yaml
@@ -14,5 +14,11 @@
           - const
     - name: Countable
       type: size
+    - name: SignedCountable
+      type: ssize
+    - name: UnsignedInt32
+      type: uint32
+    - name: UnsignedInt64
+      type: uint64
     - name: ObjectPath
       type: object_path
diff --git a/test/utility/type_traits.cpp b/test/utility/type_traits.cpp
index 33bf8c1..0a61648 100644
--- a/test/utility/type_traits.cpp
+++ b/test/utility/type_traits.cpp
@@ -1,3 +1,4 @@
+#include <sdbusplus/utility/dedup_variant.hpp>
 #include <sdbusplus/utility/type_traits.hpp>
 
 #include <type_traits>
@@ -82,4 +83,13 @@
     ASSERT_THAT(has_member_contains_v<Bar>, Eq(false));
 }
 
+// Tests for dedup_variant.
+static_assert(std::is_same_v<std::variant<size_t>,
+                             sdbusplus::utility::dedup_variant<size_t>>);
+static_assert(std::is_same_v<std::variant<char, size_t>,
+                             sdbusplus::utility::dedup_variant<char, size_t>>);
+static_assert(std::is_same_v<
+              std::variant<uint32_t, uint64_t>,
+              sdbusplus::utility::dedup_variant<uint32_t, uint64_t, size_t>>);
+
 } // namespace