diff --git a/test/integration/liquid/register-tags.ts b/test/integration/liquid/register-tags.ts
new file mode 100644
index 000000000..1b73e7a5d
--- /dev/null
+++ b/test/integration/liquid/register-tags.ts
@@ -0,0 +1,42 @@
+import { expect } from 'chai'
+import { Liquid } from '../../../src/liquid'
+
+describe('liquid#registerTag()', function () {
+  it('should support render to simple string', async () => {
+    const liquid = new Liquid()
+    liquid.registerTag('simple-string', {
+      render: () => 'B'
+    })
+    const html = await liquid.parseAndRender(`A{% simple-string %}C`)
+    return expect(html).to.equal('ABC')
+  })
+  it('should support async tag render', async () => {
+    const liquid = new Liquid()
+    liquid.registerTag('async-string', {
+      render: async () => 'B'
+    })
+    const html = await liquid.parseAndRender(`A{% async-string %}C`)
+    return expect(html).to.equal('ABC')
+  })
+  it('should have access to ctx in render()', async () => {
+    const liquid = new Liquid()
+    liquid.registerTag('dynamic-string', {
+      render: async (ctx) => ctx.get('c')
+    })
+    const html = await liquid.parseAndRender(`A{% dynamic-string %}C`, {
+      c: 'B'
+    })
+    return expect(html).to.equal('ABC')
+  })
+  it('should have access to tag arguments', async () => {
+    const liquid = new Liquid()
+    liquid.registerTag('argument-reflector', {
+      parse: function (token) { this.variable = token.args.split('=')[1] },
+      render: async function (ctx) { return ctx.get(this.variable) }
+    })
+    const html = await liquid.parseAndRender(`A{% argument-reflector variable=c %}C`, {
+      c: 'B'
+    })
+    return expect(html).to.equal('ABC')
+  })
+})
diff --git a/test/unit/template/tag-map.ts b/test/unit/template/tag-map.ts
new file mode 100644
index 000000000..d2b631bac
--- /dev/null
+++ b/test/unit/template/tag-map.ts
@@ -0,0 +1,16 @@
+import { expect } from 'chai'
+import { TagMap } from '../../../src/template/tag/tag-map'
+
+describe('TagMap', function () {
+  it('should throw when not exist', function () {
+    const map = new TagMap()
+    expect(() => map.get('not-exist'))
+      .to.throw(/tag "not-exist" not found/)
+  })
+  it('should get previously set value', function () {
+    const map = new TagMap()
+    const impl = { render: () => 'foo' }
+    map.set('foo', impl)
+    expect(map.get('foo')).to.equal(impl)
+  })
+})
diff --git a/test/unit/template/tag.ts b/test/unit/template/tag.ts
index 2f31835dc..f3104644a 100644
--- a/test/unit/template/tag.ts
+++ b/test/unit/template/tag.ts
@@ -3,7 +3,6 @@ import { Tag } from '../../../src/template/tag/tag'
 import { Context } from '../../../src/context/context'
 import * as sinon from 'sinon'
 import * as sinonChai from 'sinon-chai'
-import { Liquid } from '../../../src/liquid'
 import { TagToken } from '../../../src/parser/tag-token'
 import { toThenable } from '../../../src/util/async'
 
@@ -11,50 +10,22 @@ chai.use(sinonChai)
 const expect = chai.expect
 
 describe('Tag', function () {
-  let ctx: Context
-  let liquid: Liquid
+  const ctx = new Context()
   const emitter: any = { write: (html: string) => (emitter.html += html), html: '' }
-  before(function () {
-    ctx = new Context({
-      foo: 'bar',
-      arr: [2, 1],
-      bar: {
-        coo: 'uoo'
-      }
-    })
-    liquid = new Liquid()
-  })
-  beforeEach(function () {
-    emitter.html = ''
-  })
-
-  it('should throw when not registered', function () {
-    expect(function () {
-      new Tag({ // eslint-disable-line
-        type: 'tag',
-        content: 'foo',
-        args: '',
-        name: 'not-exist'
-      } as TagToken, [], liquid)
-    }).to.throw(/tag "not-exist" not found/)
-  })
-
-  it('should register simple tag', function () {
-    expect(function () {
-      liquid.registerTag('foo', { render: () => 'bar' })
-    }).not.throw()
-  })
 
   it('should call tag.render', async function () {
     const spy = sinon.spy()
-    liquid.registerTag('foo', { render: spy })
     const token = {
       type: 'tag',
       content: 'foo',
       args: '',
       name: 'foo'
     } as TagToken
-    await toThenable(new Tag(token, [], liquid).render(ctx, emitter))
+    await toThenable(new Tag(token, [], {
+      tags: {
+        get: () => ({ render: spy })
+      }
+    } as any).render(ctx, emitter))
     expect(spy).to.have.been.called
   })
 })