diff --git a/mail_embed_image/models/ir_mail_server.py b/mail_embed_image/models/ir_mail_server.py
index c9d125e9..dc44cdab 100644
--- a/mail_embed_image/models/ir_mail_server.py
+++ b/mail_embed_image/models/ir_mail_server.py
@@ -6,7 +6,6 @@ import uuid
 from odoo import models
 from odoo.addons.base.ir.ir_mail_server import encode_header_param
 from lxml.html.soupparser import fromstring
-from lxml import etree
 from lxml.etree import tostring
 from base64 import b64encode
 from email.mime.image import MIMEImage
diff --git a/mail_embed_image/tests/test_mail_embed_image.py b/mail_embed_image/tests/test_mail_embed_image.py
index 153a40d8..810fd69a 100644
--- a/mail_embed_image/tests/test_mail_embed_image.py
+++ b/mail_embed_image/tests/test_mail_embed_image.py
@@ -1,8 +1,11 @@
 # -*- coding: utf-8 -*-
 # Copyright 2019 Therp BV <https://therp.nl>
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl.html).
-from openerp.tests.common import TransactionCase
-from lxml import etree
+from odoo.tests.common import TransactionCase
+from requests import get
+from base64 import b64encode
+from lxml.html.soupparser import fromstring
+from odoo.addons.base.ir.ir_mail_server import encode_header_param
 
 
 class TestMailEmbedImage(TransactionCase):
@@ -11,15 +14,46 @@ class TestMailEmbedImage(TransactionCase):
     at_install = False
 
     def test_mail_embed_image(self):
-        server = self.env['ir.mail_server']
-        root = etree.Element('div')
-        etree.SubElement(root, 'img')
-        etree.SubElement(root, 'img')
-        body = etree.tostring(root)
-        message = server.build_email(
-            'test@example.com',
-            'test@example.com',
-            'subject',
-            body,
-        )
-        # TODO assertions
+        """ The following are tested here:
+        1) Create an email with no image, send it.
+        2) Create an email with three images, one base64 content, one http
+        full url and one of the format `/web/image/.*`
+
+        We assert that nothing has changed on 1) and only the `/web/image/.*`
+        has changed in 2)
+        """
+        model_mail_mail = self.env['mail.mail']
+        base_url = self.env['ir.config_parameter'].get_param('web.base.url')
+        image_url = base_url + '/mail_embed_image/static/description/icon.png'
+        image = get(image_url).content
+        body1 = '<div>this is an email</div>'
+        email1 = model_mail_mail.create({'body': body1})
+        email1.send()
+        message_body = self.env.cr.execute(
+            "SELECT body FROM mail_message WHERE message_id = %s LIMIT 1",
+            (email1.message_id, ))
+        self.assertEquals(message_body, body1)
+        body2 = """
+            <div>
+            this is an email
+            <img src="base64: %s"></img>
+            <img src="%s"></img>
+            <img src="%s"></img>
+            </div>""" % (
+                b64encode(image),
+                image_url,
+                '/web/image/res.partner/1/image',
+            )
+        email2 = model_mail_mail.create({'body': body2})
+        email2.send()
+        message_body = self.env.cr.execute(
+            "SELECT body FROM mail_message WHERE message_id = %s LIMIT 1",
+            (email1.message_id, ))
+        body2final = fromstring(message_body)
+        self.assertEquals(len(body2final.xpath('//img')), 3)
+        srcs = [x.get('src') for x in body2final.xpath('//img')]
+        self.assertIn('base64:', srcs[0])
+        self.assertIn('http:', srcs[1])
+        self.assertIn('cid:', srcs[2])
+        cid = srcs[2][3:]
+        self.assertEquals(email2.attachment_ids.name, encode_header_param(cid))