diff --git a/src/plugins/one-letter-css.js b/src/plugins/one-letter-css.js
new file mode 100644
index 00000000..e69de29b
diff --git a/test/one-letter-css.test.js b/test/one-letter-css.test.js
new file mode 100644
index 00000000..11e797f8
--- /dev/null
+++ b/test/one-letter-css.test.js
@@ -0,0 +1,98 @@
+import OneLetterCss from '../src/plugins/one-letter-css';
+
+/* webpack set */
+const workSets = [
+  {
+    in: [
+      {
+        resourcePath: './file1.css',
+      },
+      '[hash:base64:8]',
+      'theme-white',
+    ],
+    out: ['a2zADNwsK'],
+  },
+  {
+    in: [
+      {
+        resourcePath: './file1.css',
+      },
+      '[hash:base64:8]',
+      'theme-blue',
+    ],
+    out: ['b2zADNwsK'],
+  },
+  {
+    in: [
+      {
+        resourcePath: './file2.css',
+      },
+      '[hash:base64:8]',
+      'text-white',
+    ],
+    out: ['a2jlx459O'],
+  },
+  {
+    in: [
+      {
+        resourcePath: './file2.css',
+      },
+      '[hash:base64:8]',
+      'text-blue',
+    ],
+    out: ['b2jlx459O'],
+  },
+  // for develop case
+  {
+    in: [
+      {
+        resourcePath: './file2.css',
+      },
+      '[local]__[hash:base64:8]',
+      'text-blue',
+    ],
+    out: ['text-blue__b2jlx459O'],
+  },
+];
+
+/* encoding test set */
+const encodingSets = [
+  {
+    in: [0],
+    out: ['a'],
+  },
+  {
+    in: [1],
+    out: ['b'],
+  },
+  {
+    in: [51],
+    out: ['Z'],
+  },
+  {
+    in: [52],
+    out: ['ba'],
+  },
+  {
+    in: [53],
+    out: ['bb'],
+  },
+];
+
+const MyOneLetterCss = new OneLetterCss();
+
+describe('testing work case', () => {
+  workSets.forEach((set) => {
+    it(`should check name generate`, () => {
+      expect(MyOneLetterCss.getLocalIdent(...set.in)).toEqual(...set.out);
+    });
+  });
+});
+
+describe('testing encoding method', () => {
+  encodingSets.forEach((set) => {
+    it(`should check name generate`, () => {
+      expect(MyOneLetterCss.getName(...set.in)).toEqual(...set.out);
+    });
+  });
+});