diff --git a/tests/run_test b/tests/run_test
index 7f523fa..ba98b56 100755
--- a/tests/run_test
+++ b/tests/run_test
@@ -13,14 +13,12 @@ TEST_CASES = {
         (['-a=1', '-b=2'], '3')
     ],
     'flag': [
-        ([], 'flag_a = 0, flag_b = 0'),
-        (['--flag_a'], 'flag_a = 1, flag_b = 0'),
-        (['--flag_b'], 'flag_a = 0, flag_b = 1'),
-        (['--flag_a', '--flag_b'], 'flag_a = 1, flag_b = 1')
+        ([], '0'),
+        (['-f'], '1')
     ],
-    'default': [
+    'default_arg': [
         ([], '0'),
-        (['--def=1'], '1')
+        (['-d=1'], '1')
     ],
     'optional': [
         ([], 'opt = nothing'),
@@ -28,13 +26,19 @@ TEST_CASES = {
     ],
     'variadic': [
         ([], 'variadic = {}'),
-        (['1'], 'variadic = {1}'),
-        (['1', '2'], 'variadic = {1, 2}'),
         (['1', '2', '3'], 'variadic = {1, 2, 3}')
     ],
     'class': [
+        (['hello', '--msg', 'hello world'], 'hello world'),
         (['add', '-a=1', '-b=2'], '3'),
-        (['sub', '-a=1', '-b=2'], '-1')
+        (['flag'], '0'),
+        (['flag', '-f'], '1'),
+        (['default_arg'], '0'),
+        (['default_arg', '-d=1'], '1'),
+        (['optional'], 'opt = nothing'),
+        (['optional', '--opt=1'], 'opt = 1'),
+        (['variadic'], 'variadic = {}'),
+        (['variadic', '1', '2', '3'], 'variadic = {1, 2, 3}')
     ]
 }
 
diff --git a/tests/test_add.cpp b/tests/test_add.cpp
index 5f498e9..53fcba1 100644
--- a/tests/test_add.cpp
+++ b/tests/test_add.cpp
@@ -1,10 +1,8 @@
 #include <fire-llvm/fire.hpp>
 
-#include <iostream>
-
 namespace {
 
-int fire_main_add(int a, int b)
+int add(int a, int b)
 {
   return a + b;
 }
@@ -13,5 +11,5 @@ int fire_main_add(int a, int b)
 
 int main()
 {
-  fire::fire_llvm(fire_main_add);
+  fire::fire_llvm(add);
 }
diff --git a/tests/test_class.cpp b/tests/test_class.cpp
new file mode 100644
index 0000000..ea4d438
--- /dev/null
+++ b/tests/test_class.cpp
@@ -0,0 +1,57 @@
+#include <fire-llvm/fire.hpp>
+
+#include <iostream>
+#include <optional>
+#include <string>
+#include <vector>
+
+struct S
+{
+  std::string hello(std::string const &msg)
+  {
+    return msg;
+  }
+
+  int add(int a, int b)
+  {
+    return a + b;
+  }
+
+  bool flag(bool f)
+  {
+    return f;
+  }
+
+  int default_arg(int d = 0)
+  {
+    return d;
+  }
+
+  void optional(std::optional<int> opt)
+  {
+    if (opt)
+      std::cout << "opt = " << opt.value() << std::endl;
+    else
+      std::cout << "opt = nothing" << std::endl;
+  }
+
+  void variadic(std::vector<int> const &variadic)
+  {
+    std::cout << "variadic = {";
+
+    if (!variadic.empty()) {
+      std::cout << variadic[0];
+      for (std::size_t i = 1; i < variadic.size(); ++i)
+        std::cout << ", " << variadic[i];
+    }
+
+    std::cout << "}";
+  }
+};
+
+S s;
+
+int main()
+{
+  fire::fire_llvm(s);
+}
diff --git a/tests/test_default_arg.cpp b/tests/test_default_arg.cpp
index fa20c8d..442e530 100644
--- a/tests/test_default_arg.cpp
+++ b/tests/test_default_arg.cpp
@@ -1,17 +1,15 @@
 #include <fire-llvm/fire.hpp>
 
-#include <iostream>
-
 namespace {
 
-int fire_main_default(int def = 0)
+int default_arg(int d = 0)
 {
-  return def;
+  return d;
 }
 
 }
 
 int main()
 {
-  fire::fire_llvm(fire_main_default);
+  fire::fire_llvm(default_arg);
 }
diff --git a/tests/test_flag.cpp b/tests/test_flag.cpp
index 32b650f..0c896c0 100644
--- a/tests/test_flag.cpp
+++ b/tests/test_flag.cpp
@@ -1,17 +1,15 @@
 #include <fire-llvm/fire.hpp>
 
-#include <iostream>
-
 namespace {
 
-void fire_main_flag(bool flag_a, bool flag_b)
+bool flag(bool f)
 {
-  std::cout << "flag_a = " << flag_a << ", flag_b = " << flag_b << std::endl;
+  return f;
 }
 
 }
 
 int main()
 {
-  fire::fire_llvm(fire_main_flag);
+  fire::fire_llvm(flag);
 }
diff --git a/tests/test_hello.cpp b/tests/test_hello.cpp
index ad4a052..6674ce9 100644
--- a/tests/test_hello.cpp
+++ b/tests/test_hello.cpp
@@ -4,9 +4,9 @@
 
 namespace {
 
-void fire_main_hello(std::string const &msg)
+std::string fire_main_hello(std::string const &msg)
 {
-  std::cout << msg << std::endl;
+  return msg;
 }
 
 }