diff --git a/lib/urlenc/testdata/TestBasic.exp.txt b/lib/urlenc/testdata/TestBasic.exp.txt
deleted file mode 100644
index 14ce0930b..000000000
--- a/lib/urlenc/testdata/TestBasic.exp.txt
+++ /dev/null
@@ -1 +0,0 @@
-FMvBDcIwDEDRe6b4GYAFeuDOHbEAcmKjFFc4VbEQuyMGeG9OZ7JceOwxaf7qPlmTQ30Im9rw8E0TbwxrUmtd-BSIhesNC-4qhz07fV__nqmCpET5ll8AAAD__w==
\ No newline at end of file
diff --git a/lib/urlenc/testdata/TestChanges.exp.txt b/lib/urlenc/testdata/TestChanges.exp.txt
new file mode 100644
index 000000000..c8aeb9aed
--- /dev/null
+++ b/lib/urlenc/testdata/TestChanges.exp.txt
@@ -0,0 +1 @@
+vFdtb9s4Ev6uXzFwWvQuiN5sN0mFwx1yadMUaLHe2rv9UmBBiyOZrUSqJGUn3ea_L4aSbFl2usUusPkQkzPkzMNnXkhZUSIpoBR3qBMYjeB3DwDvqoJJRkwm8K3kHgDAyQmcni72NpyeOo0Pb-QnTC0wbs5gs1K-VX6mikJtzkDJpWKaC5m3a6-VXKM2zjqUitcFdppaG6WFzM8qlovGf6tabJBZ4MjrqhBpXzNHvUYOnFkGhcrzxtE378GboaoKBC5Mqtao7xMYDUXwURrUa5HiyGO8JeGKN6dzVDiiA0qZBEYnaczG2WTkPXje7lzQmkhg9NNO2LO8zzL4_4UhjiNLDu0fWdRi9lJKRyFRR9sY5ppVqy-FB5CqskRpPQBbGFYJ76G3PmjXJfCaBj-__ShvkKOmyoO51cwquHbl0NBB6ZqAKFlOUaPkT2BlbWWSMKyrQjEebMRnUSIXLFA6D2lW0SwkHEqa0K7qchnGYXwRtj5_e6tyFZh1HsbjKKru_KE8qGS-D7s9VJeeJyeUImjD2qAGWofSwuqea5crZ7AWRixFIew9ZKKwSGnmfetbbMhJYPF27l_N3sC_lkjkc6w0pkTHv4_QRkHYD8swSv_x4cCJZzeCWhFklDSLdnKjHWwOTQD3uaWZCSxqzYzVdWqJgdCoVLAijOKJ35r0Y-JrGKmHnkeCfCz-YrZSEmGDy8cXdxzdLhYzuJJcK8G9DS4T-IDLH0bNvtYaww-4fDqO5k1uPx1H19SHw6uq2pO-VCUT0hw_lPemIsxJz_OzzrUxF8H668Y5FCZ0W8Jf0bXuD0JjgcaErKoK9IWz4sdj_3yaL_2q1iR9PoniC7_8JONJUfjsf084Eia_yJ88O4TSkpEcISHlchqQKBPUiB0ialcNO6Epmba-g2B8i-lKqkLlAk34PB6HrLHb6F0ZHLKwwaXLw23UdjloUqVdY-8a90c5d6LRke6WZRyzmLrbSpUImsnPtPeWJu_dxOtZ7pre9kqYP9qmDuAsVlpkFt7Pro-s3nO-Q9m7CROYDsQEP4qiV5OXBP97CFqQzknb8G-3Y-fu5NGmf7z--6b-EtydgSNkDbR_n5zHvLXElEyumLVMwjiBd93Ey8VXuqvTzwm87oZe034cFQnM3aS5dzxLzfi-EpQfbggzgQPXPU8DzdbZQN7zNzxG569tCYN6aKtzIK00cuHei93pxwnMdsI2of_84ku59F0x-5XMg6xglmau0KmGz6fnsft3Gb9obzKHvqsGl39NWX63KreE9QNTYpmydIUJvGtHR1oQj7-cZxHD4i6qlA7SQtU8o-smkGjDShPZ1i9UrkzIMZrGz6OpH3G-9KeT7NxfXr5AP8NoOo0macouud955e15vAxtukrghn56h-gewAlYXeOOR3rhNtuYrTXSRjf48a1EnpB54oiji_qHdzqolAqt8w6Ey7DGmHckN_6p1GghEJpDEDvw2140DlLdvDz6WbVXYPQoPNRuE2c0GuqOVEb_Ttg2on6L2qkOoSVwzSQXnFlsUmTXSsfbF-tjLeuwIOiP5Dvr-t22fQ-X31zcXN68ouUP9GnDdHG_FJon8IqG_xea3o-1ZXkCv1jm7teKUbjn9NO-n2sprECTwPVu4j14aNMEgiBAmx7w63RdWt92L1Gvn23bAO0J27j0Zc7WjsLme9F4fwQAAP__
\ No newline at end of file
diff --git a/lib/urlenc/urlenc_test.go b/lib/urlenc/urlenc_test.go
index 21c33087d..5b492938f 100644
--- a/lib/urlenc/urlenc_test.go
+++ b/lib/urlenc/urlenc_test.go
@@ -16,8 +16,169 @@ I just forgot my whole philosophy of life!!!: {
 	encoded, err := Encode(script)
 	assert.Success(t, err)
 
-	// Make it explicit in PRs when encoding changes
-	// Something we might want to know for playground compatability
+	decoded, err := Decode(encoded)
+	assert.Success(t, err)
+
+	assert.String(t, script, decoded)
+}
+
+// TestChanges makes it explicit in PRs when encoding changes
+// Something we might want to know for playground compatability
+func TestChanges(t *testing.T) {
+	// Choose something with many keywords and varied text
+	const script = `timeline mixer: "" {
+  explanation: |md
+    ## **Timeline mixer**
+    - Inject ads, who-to-follow, onboarding
+    - Conversation module
+    - Cursoring,pagination
+    - Tweat deduplication
+    - Served data logging
+  |
+}
+People discovery: "People discovery \nservice"
+admixer: Ad mixer {
+  style.fill: "#c1a2f3"
+}
+
+onboarding service: "Onboarding \nservice"
+timeline mixer -> People discovery
+timeline mixer -> onboarding service
+timeline mixer -> admixer
+container0: "" {
+  graphql
+  comment
+  tlsapi
+}
+container0.graphql: GraphQL\nFederated Strato Column {
+  shape: image
+  icon: https://upload.wikimedia.org/wikipedia/commons/thumb/1/17/GraphQL_Logo.svg/1200px-GraphQL_Logo.svg.png
+}
+container0.comment: |md
+  ## Tweet/user content hydration, visibility filtering
+|
+container0.tlsapi: TLS-API (being deprecated)
+container0.graphql -> timeline mixer
+timeline mixer <- container0.tlsapi
+twitter fe: "Twitter Frontend " {
+  icon: https://icons.terrastruct.com/social/013-twitter-1.svg
+  shape: image
+}
+twitter fe -> container0.graphql: iPhone web
+twitter fe -> container0.tlsapi: HTTP Android
+web: Web {
+  icon: https://icons.terrastruct.com/azure/Web%20Service%20Color/App%20Service%20Domains.svg
+  shape: image
+}
+
+Iphone: {
+  icon: 'https://ss7.vzw.com/is/image/VerizonWireless/apple-iphone-12-64gb-purple-53017-mjn13ll-a?$device-lg$'
+  shape: image
+}
+Android: {
+  icon: https://cdn4.iconfinder.com/data/icons/smart-phones-technologies/512/android-phone.png
+  shape: image
+}
+
+web -> twitter fe
+timeline scorer: "Timeline\nScorer" {
+  style.fill: "#ffdef1"
+}
+home ranker: Home Ranker
+
+timeline service: Timeline Service
+timeline mixer -> timeline scorer: Thrift RPC
+timeline mixer -> home ranker: {
+  style.stroke-dash: 4
+  style.stroke: "#000E3D"
+}
+timeline mixer -> timeline service
+home mixer: Home mixer {
+  # style.fill: "#c1a2f3"
+}
+container0.graphql -> home mixer: {
+  style.stroke-dash: 4
+  style.stroke: "#000E3D"
+}
+home mixer -> timeline scorer
+home mixer -> home ranker: {
+  style.stroke-dash: 4
+  style.stroke: "#000E3D"
+}
+home mixer -> timeline service
+manhattan 2: Manhattan
+gizmoduck: Gizmoduck
+socialgraph: Social graph
+tweetypie: Tweety Pie
+home mixer -> manhattan 2
+home mixer -> gizmoduck
+home mixer -> socialgraph
+home mixer -> tweetypie
+Iphone -> twitter fe
+Android -> twitter fe
+prediction service2: Prediction Service {
+  shape: image
+  icon: https://cdn-icons-png.flaticon.com/512/6461/6461819.png
+}
+home scorer: Home Scorer {
+  style.fill: "#ffdef1"
+}
+manhattan: Manhattan
+memcache: Memcache {
+  icon: https://d1q6f0aelx0por.cloudfront.net/product-logos/de041504-0ddb-43f6-b89e-fe04403cca8d-memcached.png
+}
+
+fetch: Fetch {
+  style.multiple: true
+  shape: step
+}
+
+feature: Feature {
+  style.multiple: true
+  shape: step
+}
+scoring: Scoring {
+  style.multiple: true
+  shape: step
+}
+fetch -> feature
+feature -> scoring
+
+prediction service: Prediction Service {
+  shape: image
+  icon: https://cdn-icons-png.flaticon.com/512/6461/6461819.png
+}
+scoring -> prediction service
+fetch -> container2.crmixer
+
+home scorer -> manhattan: ""
+
+home scorer -> memcache: ""
+home scorer -> prediction service2
+home ranker -> home scorer
+home ranker -> container2.crmixer: Candidate Fetch
+container2: "" {
+  style.stroke: "#000E3D"
+  style.fill: "#ffffff"
+  crmixer: CrMixer {
+    style.fill: "#F7F8FE"
+  }
+  earlybird: EarlyBird
+  utag: Utag
+  space: Space
+  communities: Communities
+}
+etc: ...etc
+
+home scorer -> etc: Feature Hydration
+
+feature -> manhattan
+feature -> memcache
+feature -> etc: Candidate sources
+`
+
+	encoded, err := Encode(script)
+	assert.Success(t, err)
 	assert.Testdata(t, ".txt", []byte(encoded))
 
 	decoded, err := Decode(encoded)