diff --git a/tests/unit/document.test.ts b/tests/unit/document.test.ts
new file mode 100644
index 0000000..3f3ad15
--- /dev/null
+++ b/tests/unit/document.test.ts
@@ -0,0 +1,36 @@
+import { createStore } from '../../src'
+import { getDocumentType, isDocument } from '../../src/document'
+import { Document } from '../../src/types'
+import { User, schema, TypesMap } from '../fixtures'
+import { userFactory } from '../utils/factories'
+
+const store = createStore<TypesMap>({
+  schema,
+})
+
+afterEach(() => store.reset())
+
+describe('`isDocument`', () => {
+  it('should return `true` if the input is document', () => {
+    const data = userFactory()
+    store.add('User', data)
+    const user = store.findFirst('User')
+
+    expect(isDocument(user)).toEqual(true)
+  })
+
+  it('should return `false` if the input is not a document', () => {
+    const data = userFactory()
+    expect(isDocument(data)).toEqual(false)
+  })
+})
+describe('`getDocumentType`', () => {
+  it('should get the document type', () => {
+    const data = userFactory()
+
+    store.add('User', data)
+    const user = store.findFirstOrThrow('User') as Document<User>
+
+    expect(getDocumentType(user)).toEqual('User')
+  })
+})