diff --git a/tests/modules/string.test.ts b/tests/modules/string.test.ts
new file mode 100644
index 0000000..06e45e8
--- /dev/null
+++ b/tests/modules/string.test.ts
@@ -0,0 +1,28 @@
+import "../../src/modules/string";
+
+describe("Capitalize", () => {
+  {
+    const name = "test";
+    test(name, () => {
+      expect(name.capitalize()).toBe("Test");
+    });
+  }
+  {
+    const name = "MACHIN";
+    test(name, () => {
+      expect(name.capitalize()).toBe("MACHIN");
+    });
+  }
+  {
+    const name = "tRUC";
+    test(name, () => {
+      expect(name.capitalize()).toBe("TRUC");
+    });
+  }
+  {
+    const name = "Super";
+    test(name, () => {
+      expect(name.capitalize()).toBe("Super");
+    });
+  }
+});