diff --git a/tests/spec/transformers/valid/AddMandatoryTags/keep-existing-tags-ampjs/expected_output.html b/tests/spec/transformers/valid/AddMandatoryTags/keep-existing-tags-ampjs/expected_output.html
new file mode 100644
index 000000000..168f7e570
--- /dev/null
+++ b/tests/spec/transformers/valid/AddMandatoryTags/keep-existing-tags-ampjs/expected_output.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html ⚡>
+<head>
+  <title>My AMP Page</title>
+  <link rel="canonical" href="self.html">
+  <script data-auto async src="https://ampjs.org/v0.js"></script>
+  <meta data-auto charset="utf-8">
+  <meta data-auto name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1"><noscript data-auto><style data-auto amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript><style data-auto amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style>
+</head>
+<body>
+  <h1>hello world</h1>
+</body>
+</html>
\ No newline at end of file
diff --git a/tests/spec/transformers/valid/AddMandatoryTags/keep-existing-tags-ampjs/input.html b/tests/spec/transformers/valid/AddMandatoryTags/keep-existing-tags-ampjs/input.html
new file mode 100644
index 000000000..801dd6079
--- /dev/null
+++ b/tests/spec/transformers/valid/AddMandatoryTags/keep-existing-tags-ampjs/input.html
@@ -0,0 +1,10 @@
+<html ⚡>
+<head>
+  <title>My AMP Page</title>
+  <link rel="canonical" href="self.html" />
+  <script data-auto async src="https://ampjs.org/v0.js"></script>
+</head>
+<body>
+  <h1>hello world</h1>
+</body>
+</html>
diff --git a/tests/spec/transformers/valid/RewriteAmpUrls/adds_lts_ampjs/expected_output.html b/tests/spec/transformers/valid/RewriteAmpUrls/adds_lts_ampjs/expected_output.html
new file mode 100644
index 000000000..aa570f4cf
--- /dev/null
+++ b/tests/spec/transformers/valid/RewriteAmpUrls/adds_lts_ampjs/expected_output.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html ⚡>
+<head>
+  <script async custom-element="amp-experiment" src="https://cdn.ampproject.org/lts/v0/amp-experiment-0.1.js"></script>
+  <script async src="https://cdn.ampproject.org/lts/v0.js"></script>
+  <link rel="stylesheet" href="https://cdn.ampproject.org/lts/v0.css">
+  <link href="https://fonts.googleapis.com/css?foobar" rel="stylesheet" type="text/css">
+  <link href="https://example.com/favicon.ico" rel="icon">
+  <link rel="preload" href="https://cdn.ampproject.org/lts/v0.js" as="script">
+  <link rel="preload" href="https://cdn.ampproject.org/lts/v0.css" as="style">
+</head>
+<body></body>
+</html>
\ No newline at end of file
diff --git a/tests/spec/transformers/valid/RewriteAmpUrls/adds_lts_ampjs/input.html b/tests/spec/transformers/valid/RewriteAmpUrls/adds_lts_ampjs/input.html
new file mode 100644
index 000000000..3e5da0cf2
--- /dev/null
+++ b/tests/spec/transformers/valid/RewriteAmpUrls/adds_lts_ampjs/input.html
@@ -0,0 +1,16 @@
+<!--
+{
+  "lts": true
+}
+-->
+<!doctype html>
+<html ⚡>
+<head>
+  <script async custom-element=amp-experiment src=https://ampjs.org/v0/amp-experiment-0.1.js></script>
+  <script async src="https://ampjs.org/v0.js"></script>
+  <link rel=stylesheet href=https://ampjs.org/v0.css>
+  <link href=https://fonts.googleapis.com/css?foobar rel=stylesheet type=text/css>
+  <link href=https://example.com/favicon.ico rel=icon>
+</head>
+<body></body>
+</html>
diff --git a/tests/spec/transformers/valid/RewriteAmpUrls/adds_preloads_ampjs/expected_output.html b/tests/spec/transformers/valid/RewriteAmpUrls/adds_preloads_ampjs/expected_output.html
new file mode 100644
index 000000000..4a160fd16
--- /dev/null
+++ b/tests/spec/transformers/valid/RewriteAmpUrls/adds_preloads_ampjs/expected_output.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html ⚡>
+<head>
+  <script async custom-element="amp-experiment" src="https://cdn.ampproject.org/v0/amp-experiment-0.1.js"></script>
+  <script async src="https://cdn.ampproject.org/v0.js"></script>
+  <link rel="stylesheet" href="https://cdn.ampproject.org/v0.css">
+  <link href="https://fonts.googleapis.com/css?foobar" rel="stylesheet" type="text/css">
+  <link href="https://example.com/favicon.ico" rel="icon">
+  <link rel="preload" href="https://cdn.ampproject.org/v0.js" as="script">
+  <link rel="preload" href="https://cdn.ampproject.org/v0.css" as="style">
+</head>
+<body></body>
+</html>
\ No newline at end of file
diff --git a/tests/spec/transformers/valid/RewriteAmpUrls/adds_preloads_ampjs/input.html b/tests/spec/transformers/valid/RewriteAmpUrls/adds_preloads_ampjs/input.html
new file mode 100644
index 000000000..cf97424d6
--- /dev/null
+++ b/tests/spec/transformers/valid/RewriteAmpUrls/adds_preloads_ampjs/input.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<html ⚡>
+<head>
+  <script async custom-element=amp-experiment src=https://ampjs.org/v0/amp-experiment-0.1.js></script>
+  <script async src="https://ampjs.org/v0.js"></script>
+  <link rel=stylesheet href=https://ampjs.org/v0.css>
+  <link href=https://fonts.googleapis.com/css?foobar rel=stylesheet type=text/css>
+  <link href=https://example.com/favicon.ico rel=icon>
+</head>
+<body></body>
+</html>
