diff --git a/src/content/hint.js b/src/content/hint.js
index 7979cf1..f59899d 100644
--- a/src/content/hint.js
+++ b/src/content/hint.js
@@ -2,6 +2,10 @@ import './hint.css';
 
 export default class Hint {
   constructor(target, tag) {
+    if (!(document.body instanceof HTMLElement)) {
+      throw new TypeError('target is not an HTMLElement');
+    }
+
     this.target = target;
 
     let doc = target.ownerDocument
@@ -31,8 +35,7 @@ export default class Hint {
 
   activate() {
     if (this.target.tagName.toLowerCase() === 'a') {
-      let href = this.target.href;
-      window.location.href = href;
+      this.target.click();
     }
   }
 }
diff --git a/test/content/hint.html b/test/content/hint.html
new file mode 100644
index 0000000..b50c5fe
--- /dev/null
+++ b/test/content/hint.html
@@ -0,0 +1 @@
+<a id='test-link' href='javascript:window.vimvixenTest="hello"' >link</a>
diff --git a/test/content/hint.test.js b/test/content/hint.test.js
new file mode 100644
index 0000000..9b2ab6e
--- /dev/null
+++ b/test/content/hint.test.js
@@ -0,0 +1,58 @@
+import { expect } from "chai";
+import Hint from '../../src/content/hint';
+
+describe('Hint class', () => {
+  beforeEach(() => {
+    document.body.innerHTML = __html__['test/content/hint.html'];
+  });
+
+  describe('#constructor', () => {
+    it('creates a hint element with tag name', () => {
+      let link = document.getElementById('test-link');
+      let hint = new Hint(link, 'abc');
+      expect(hint.element.textContent.trim()).to.be.equal('abc');
+    });
+
+    it('throws an exception when non-element given', () => {
+      expect(() => new Hint(window, 'abc')).to.throw(TypeError);
+    });
+  });
+
+  describe('#show', () => {
+    it('shows an element', () => {
+      let link = document.getElementById('test-link');
+      let hint = new Hint(link, 'abc');
+      hint.hide();
+      hint.show();
+
+      expect(hint.element.style.display).to.not.equal('none');
+    });
+  });
+
+  describe('#hide', () => {
+    it('hides an element', () => {
+      let link = document.getElementById('test-link');
+      let hint = new Hint(link, 'abc');
+      hint.hide();
+
+      expect(hint.element.style.display).to.equal('none');
+    });
+  });
+
+  describe('#remove', () => {
+    it('removes an element', () => {
+      let link = document.getElementById('test-link');
+      let hint = new Hint(link, 'abc');
+
+      expect(hint.element.parentElement).to.not.be.null;
+      hint.remove();
+      expect(hint.element.parentElement).to.be.null;
+    });
+  });
+
+  describe('#activate', () => {
+    // TODO test activations
+  });
+});
+
+