Markdown->Slack refactor and fix for nested bold/italic rendering (#21905)

* refactor markdown->slack code to use a multimethod

* solve nested bold & italic issue

* fix docstring position

* fix tests

* restore a couple of comments

* replace mrkdwn with slack in tests

src/metabase/pulse.clj

@@ -132,7 +132,7 @@
                 :attachment-name "image.png"
                 :channel-id      channel-id
                 :fallback        card-name}
-               (let [mrkdwn (markdown/process-markdown (:text card-result) :mrkdwn)]
+               (let [mrkdwn (markdown/process-markdown (:text card-result) :slack)]
                  (when (not (str/blank? mrkdwn))
                    {:blocks [{:type "section"
                               :text {:type "mrkdwn"

src/metabase/pulse/markdown.clj

@@ -2,6 +2,7 @@
   (:require [clojure.edn :as edn]
             [clojure.java.io :as io]
             [clojure.string :as str]
+            [clojure.walk :as walk]
             [metabase.public-settings :as public-settings])
   (:import [com.vladsch.flexmark.ast AutoLink BlockQuote BulletList BulletListItem Code Emphasis FencedCodeBlock
             HardLineBreak Heading HtmlBlock HtmlCommentBlock HtmlEntity HtmlInline HtmlInlineBase HtmlInlineComment
@@ -37,8 +38,8 @@
    Emphasis              :italic
    OrderedList           :ordered-list
    BulletList            :unordered-list
-   OrderedListItem       :ordered-list-item
-   BulletListItem        :unordered-list-item
+   OrderedListItem       :list-item
+   BulletListItem        :list-item
    Code                  :code
    FencedCodeBlock       :codeblock
    IndentedCodeBlock     :codeblock
@@ -203,113 +204,174 @@
         (.. (URI. site-url) (resolve uri) toString)
         uri))))
 
-(defn- ast->mrkdwn
-  "Takes an AST representing Markdown input, and converts it to a mrkdwn string that will render nicely in Slack.
+(defn- ^:private strip-tag
+  "Given the value from the :content field of a Markdown AST node, and a keyword representing a tag type, converts all
+  instances of the tag in the content to `:default` tags. This is used to suppress rendering of nested bold and italic
+  tags, which Slack doesn't support."
+  [content tag]
+  (walk/postwalk
+   (fn [node]
+     (if (and (map? node) (= (:tag node) tag))
+        (assoc node :tag :default)
+        node))
+   content))
+
+(defmulti ast->slack
+  "Takes an AST representing Markdown input, and converts it to a string that will render nicely in Slack.
 
   Some of the differences to Markdown include:
-    * All headers are just rendered as bold text.
-    * Ordered and unordered lists are printed in plain text.
-    * Inline images are rendered as text that links to the image source, e.g. <image.png|[Image: alt-text]>."
-  [{:keys [tag attrs content]}]
-  (let [resolved-content (if (string? content)
-                           (escape-text content)
-                           (map #(if (string? %)
-                                   (escape-text %)
-                                   (ast->mrkdwn %))
-                                content))
-        joined-content   (str/join resolved-content)]
-    (case tag
-      :document
-      joined-content
-
-      :paragraph
-      (str joined-content "\n")
-
-      :soft-line-break
-      " "
-
-      :hard-line-break
-      "\n"
-
-      :horizontal-line
-      "\n───────────────────\n"
-
-      :heading
-      (str "*" joined-content "*\n")
-
-      :bold
-      (str "*" joined-content "*")
-
-      :italic
-      (str "_" joined-content "_")
-
-      :code
-      (str "`" joined-content "`")
-
-      :codeblock
-      (str "```\n" joined-content "```")
-
-      :blockquote
-      (let [lines (str/split-lines joined-content)]
-        (str/join "\n" (map #(str ">" %) lines)))
-
-      :link
-      (let [resolved-uri (resolve-uri (:href attrs))]
-        (if (contains? #{:image :image-ref} (:tag (first content)))
-          ;; If this is a linked image, add link target on separate line after image placeholder
-          (str joined-content "\n(" resolved-uri ")")
-          (str "<" resolved-uri "|" joined-content ">")))
-
-      :link-ref
-      (if-let [resolved-uri (resolve-uri (-> attrs :reference :attrs :url))]
-        (str "<" resolved-uri "|" joined-content ">")
-        ;; If this was parsed as a link-ref but has no reference, assume it was just a pair of square brackets and
-        ;; restore them. This is a known discrepency between flexmark-java and Markdown rendering on the frontend.
-        (str "[" joined-content "]"))
-
-      :auto-link
-      (str "<" (:href attrs) ">")
-
-      :mail-link
-      (str "<mailto:" (:address attrs) "|" (:address attrs) ">")
-
-      ;; list items might have nested lists or other elements, which should have their indentation level increased
-      (:unordered-list-item :ordered-list-item)
-      (let [indented-content (->> (rest resolved-content)
-                                  str/join
-                                  str/split-lines
-                                  (map #(str "    " %))
-                                  (str/join "\n"))]
-        (if-not (str/blank? indented-content)
-          (str (first resolved-content) indented-content "\n")
-          joined-content))
-
-      :unordered-list
-      (str/join (map #(str "• " %) resolved-content))
-
-      :ordered-list
-      (str/join (map-indexed #(str (inc %1) ". " %2) resolved-content))
-
-      ;; Replace images with text that links to source, including alt text if available
-      :image
-      (let [{:keys [src alt]} attrs]
-        (if (str/blank? alt)
-          (str "<" src "|[Image]>")
-          (str "<" src "|[Image: " alt "]>")))
-
-      :image-ref
-      (let [src (-> attrs :reference :attrs :url)
-            alt joined-content]
-        (if (str/blank? alt)
-          (str "<" src "|[Image]>")
-          (str "<" src "|[Image: " alt "]>")))
-
-      :html-entity
-      (some->> content
-               (get @html-entities)
-               (:characters))
-
-      joined-content)))
+  * All headers are just rendered as bold text.
+  * Ordered and unordered lists are printed in plain text.
+  * Inline images are rendered as text that links to the image source, e.g. <image.png|[Image: alt-text]>."
+  :tag)
+
+(defn ^:private resolved-content
+  "Given the value from the :content field of a Markdown AST node, recursively resolves subnodes into a nested list of
+  strings."
+  [content]
+  (if (string? content)
+    (escape-text content)
+    (map #(if (string? %)
+            (escape-text %)
+            (ast->slack %))
+         content)))
+
+(defn ^:private resolved-content-string
+  "Given the resolved content of a Markdown AST node, converts it into a single flattened string. This is used for
+  rendering a couple specific types of nodes, such as list items."
+  [resolved-content]
+  (-> resolved-content
+      flatten
+      str/join))
+
+(defn ^:private resolved-lines
+  "Given the value from the :content field of a Markdown AST node, recursively resolves it and returns a list of
+  strings corresponding to individual lines in the result."
+  [content]
+  (-> content
+      resolved-content
+      resolved-content-string
+      str/split-lines))
+
+(defmethod ast->slack :default
+  [{content :content}]
+  (resolved-content content))
+
+(defmethod ast->slack :document
+  [{content :content}]
+  (resolved-content content))
+
+(defmethod ast->slack :paragraph
+  [{content :content}]
+  [(resolved-content content) "\n"])
+
+(defmethod ast->slack :soft-line-break
+  [_]
+  " ")
+
+(defmethod ast->slack :hard-line-break
+  [_]
+  "\n")
+
+(defmethod ast->slack :horizontal-line
+  [_]
+  "\n───────────────────\n")
+
+(defmethod ast->slack :heading
+  [{content :content}]
+  ["*" (resolved-content content) "*\n"])
+
+(defmethod ast->slack :bold
+  [{content :content}]
+  ["*" (resolved-content (strip-tag content :bold)) "*"])
+
+(defmethod ast->slack :italic
+  [{content :content}]
+  ["_" (resolved-content (strip-tag content :italic)) "_"])
+
+(defmethod ast->slack :code
+  [{content :content}]
+  ["`" (resolved-content content) "`"])
+
+(defmethod ast->slack :codeblock
+  [{content :content}]
+  ["```\n" (resolved-content content) "```"])
+
+(defmethod ast->slack :blockquote
+  [{content :content}]
+  (let [lines (resolved-lines content)]
+    (interpose "\n" (map (fn [line] [">" line]) lines))))
+
+(defmethod ast->slack :link
+  [{:keys [content attrs]}]
+  (let [resolved-uri     (resolve-uri (:href attrs))
+        resolved-content (resolved-content content)]
+    (if (contains? #{:image :image-ref} (:tag (first content)))
+      ;; If this is a linked image, add link target on separate line after image placeholder
+      [resolved-content "\n(" resolved-uri ")"]
+      ["<" resolved-uri "|" resolved-content ">"])))
+
+(defmethod ast->slack :link-ref
+  [{:keys [content attrs]}]
+  (let [resolved-uri     (resolve-uri (-> attrs :reference :attrs :url))
+        resolved-content (resolved-content content)]
+    (if resolved-uri
+      ["<" resolved-uri "|" resolved-content ">"]
+      ;; If this was parsed as a link-ref but has no reference, assume it was just a pair of square brackets and
+      ;; restore them. This is a known discrepency between flexmark-java and Markdown rendering on the frontend.
+      ["[" resolved-content "]"])))
+
+(defmethod ast->slack :auto-link
+  [{{href :href} :attrs}]
+  ["<" href ">"])
+
+(defmethod ast->slack :mail-link
+  [{{address :address} :attrs}]
+  ["<mailto:"  address "|" address ">"])
+
+(defmethod ast->slack :list-item
+  [{content :content}]
+  (let [resolved-content (resolved-content content)
+        ;; list items might have nested lists or other elements, which should have their indentation level increased
+        indented-content (->> (rest resolved-content)
+                              resolved-content-string
+                              str/split-lines
+                              (map #(str "    " %))
+                              (str/join "\n"))]
+    (if-not (str/blank? indented-content)
+      [(first resolved-content) indented-content "\n"]
+      resolved-content)))
+
+(defmethod ast->slack :unordered-list
+  [{content :content}]
+  (map (fn [list-item] ["• " list-item])
+       (resolved-content content)))
+
+(defmethod ast->slack :ordered-list
+  [{content :content}]
+  (map-indexed (fn [idx list-item] [(inc idx) ". " list-item])
+               (resolved-content content)))
+
+(defmethod ast->slack :image
+  [{{:keys [src alt]} :attrs}]
+  ;; Replace images with text that links to source, including alt text if available
+  (if (str/blank? alt)
+    ["<" src "|[Image]>"]
+    ["<" src "|[Image: " alt "]>"]))
+
+(defmethod ast->slack :image-ref
+  [{:keys [content attrs]}]
+  (let [src (-> attrs :reference :attrs :url)
+        alt (-> content resolved-content resolved-content-string)]
+    (if (str/blank? alt)
+      ["<" src "|[Image]>"]
+      ["<" src "|[Image: " alt "]>"])))
+
+(defmethod ast->slack :html-entity
+  [{content :content}]
+  (some->> content
+           (get @html-entities)
+           (:characters)))
 
 (defn- empty-link-ref?
   "Returns true if this node was parsed as a link ref, but has no references. This probably means the original text
@@ -342,14 +404,16 @@
 
 (defmulti process-markdown
   "Converts a markdown string from a virtual card into a form that can be sent to a channel
-  (mrkdwn for Slack; HTML for email)."
+  (Slack's markup language, or HTML for email)."
   (fn [_markdown channel-type] channel-type))
 
-(defmethod process-markdown :mrkdwn
+(defmethod process-markdown :slack
   [markdown _]
   (-> (.parse ^Parser parser ^String markdown)
       to-clojure
-      ast->mrkdwn
+      ast->slack
+      flatten
+      str/join
       str/trim))
 
 (defmethod process-markdown :html

test/metabase/pulse/markdown_test.clj

@@ -4,9 +4,9 @@
             [metabase.pulse.markdown :as markdown]
             [metabase.test.util :as tu]))
 
-(defn- mrkdwn
+(defn- slack
   [markdown]
-  (markdown/process-markdown markdown :mrkdwn))
+  (markdown/process-markdown markdown :slack))
 
 (defn- escape
   [text]
@@ -14,162 +14,172 @@
 
 (deftest process-markdown-slack-test
   (testing "Headers are converted to bold text"
-    (is (= "*header*"          (mrkdwn "# header")))
-    (is (= "*header*"          (mrkdwn "## header")))
-    (is (= "*header*"          (mrkdwn "### header")))
-    (is (= "*header*"          (mrkdwn "#### header")))
-    (is (= "*header*"          (mrkdwn "##### header")))
-    (is (= "*header*"          (mrkdwn "###### header")))
-    (is (= "*header*"          (mrkdwn "header\n=========")))
-    (is (= "*header*"          (mrkdwn "header\n---------")))
-    (is (= "*header*\ncontent" (mrkdwn "# header\ncontent"))))
+    (is (= "*header*"          (slack "# header")))
+    (is (= "*header*"          (slack "## header")))
+    (is (= "*header*"          (slack "### header")))
+    (is (= "*header*"          (slack "#### header")))
+    (is (= "*header*"          (slack "##### header")))
+    (is (= "*header*"          (slack "###### header")))
+    (is (= "*header*"          (slack "header\n=========")))
+    (is (= "*header*"          (slack "header\n---------")))
+    (is (= "*header*\ncontent" (slack "# header\ncontent"))))
 
   (testing "Bold and italic text uses Slack's syntax"
-    (is (= "*bold*"   (mrkdwn "**bold**")))
-    (is (= "*bold*"   (mrkdwn "__bold__")))
-    (is (= "_italic_" (mrkdwn "*italic*")))
-    (is (= "_italic_" (mrkdwn "_italic_")))
-    (is (= "_*both*_" (mrkdwn "***both***")))
-    (is (= "*_both_*" (mrkdwn "__*both*__")))
-    (is (= "*_both_*" (mrkdwn "**_both_**")))
-    (is (= "_*both*_" (mrkdwn "___both___"))))
+    (is (= "*bold*"   (slack "**bold**")))
+    (is (= "*bold*"   (slack "__bold__")))
+    (is (= "_italic_" (slack "*italic*")))
+    (is (= "_italic_" (slack "_italic_")))
+    (is (= "_*both*_" (slack "***both***")))
+    (is (= "*_both_*" (slack "__*both*__")))
+    (is (= "*_both_*" (slack "**_both_**")))
+    (is (= "_*both*_" (slack "___both___"))))
+
+  (testing "Nested bold or italic only render the top-level syntax"
+    (is (= "*bold extra bold*"           (slack "**bold **extra bold****")))
+    (is (= "*bold extra extra bold*"     (slack "**bold **extra **extra bold******")))
+    (is (= "*bold extra bold*"           (slack "__bold __extra bold____")))
+    (is (= "*bold extra extra bold*"     (slack "__bold __extra __extra bold______")))
+    (is (= "_italic extra italic_"       (slack "*italic *extra italic**")))
+    (is (= "_italic extra extra italic_" (slack "*italic *extra *extra italic***")))
+    (is (= "_italic extra italic_"       (slack "_italic _extra italic__")))
+    (is (= "_italic extra extra italic_" (slack "_italic _extra _extra italic___"))))
 
   (testing "Lines are correctly split or joined"
-    (is (= "foo bar"  (mrkdwn "foo\nbar")))
-    (is (= "foo\nbar" (mrkdwn "foo\n\nbar")))
-    (is (= "foo\nbar" (mrkdwn "foo  \nbar")))
-    (is (= "foo\nbar" (mrkdwn "foo\\\nbar"))))
+    (is (= "foo bar"  (slack "foo\nbar")))
+    (is (= "foo\nbar" (slack "foo\n\nbar")))
+    (is (= "foo\nbar" (slack "foo  \nbar")))
+    (is (= "foo\nbar" (slack "foo\\\nbar"))))
 
   (testing "Horizontal lines are created using box drawing characters"
-    (is (= "───────────────────" (mrkdwn "----")))
-    (is (= "text\n\n───────────────────\ntext" (mrkdwn "text\n\n----\ntext"))))
+    (is (= "───────────────────"               (slack "----")))
+    (is (= "text\n\n───────────────────\ntext" (slack "text\n\n----\ntext"))))
 
   (testing "Code blocks are preserved"
-    (is (= "`code`"                (mrkdwn "`code`")))
-    (is (= "```\ncode\nblock```"   (mrkdwn "    code\n    block")))
-    (is (= "```\ncode\nblock\n```" (mrkdwn "```\ncode\nblock\n```")))
-    (is (= "```\ncode\nblock\n```" (mrkdwn "```lang\ncode\nblock\n```")))
-    (is (= "```\ncode\nblock\n```" (mrkdwn "~~~\ncode\nblock\n~~~"))))
+    (is (= "`code`"                (slack "`code`")))
+    (is (= "```\ncode\nblock```"   (slack "    code\n    block")))
+    (is (= "```\ncode\nblock\n```" (slack "```\ncode\nblock\n```")))
+    (is (= "```\ncode\nblock\n```" (slack "```lang\ncode\nblock\n```")))
+    (is (= "```\ncode\nblock\n```" (slack "~~~\ncode\nblock\n~~~"))))
 
   (testing "Blockquotes are preserved"
-    (is (= ">block"               (mrkdwn ">block")))
-    (is (= ">block"               (mrkdwn "> block")))
-    (is (= ">block quote"         (mrkdwn ">block\n>quote")))
-    (is (= ">block quote"         (mrkdwn ">block\n>quote")))
-    (is (= ">• quoted\n>• list"   (mrkdwn "> * quoted\n> * list")))
-    (is (= ">1. quoted\n>2. list" (mrkdwn "> 1. quoted\n> 1. list")))
-    (is (= ">quote\n>• footer"    (mrkdwn ">quote\n>- footer"))))
+    (is (= ">block"               (slack ">block")))
+    (is (= ">block"               (slack "> block")))
+    (is (= ">block quote"         (slack ">block\n>quote")))
+    (is (= ">block quote"         (slack ">block\n>quote")))
+    (is (= ">• quoted\n>• list"   (slack "> * quoted\n> * list")))
+    (is (= ">1. quoted\n>2. list" (slack "> 1. quoted\n> 1. list")))
+    (is (= ">quote\n>• footer"    (slack ">quote\n>- footer"))))
 
   (testing "Links use Slack's syntax, tooltips are dropped, link formatting is preserved"
-    (is (= "<https://metabase.com|Metabase>"   (mrkdwn "[Metabase](https://metabase.com)")))
-    (is (= "<https://metabase.com|Metabase>"   (mrkdwn "[Metabase](https://metabase.com \"tooltip\")")))
-    (is (= "<https://metabase.com|_Metabase_>" (mrkdwn "[*Metabase*](https://metabase.com)")))
-    (is (= "<https://metabase.com|_Metabase_>" (mrkdwn "[_Metabase_](https://metabase.com)")))
-    (is (= "<https://metabase.com|*Metabase*>" (mrkdwn "[**Metabase**](https://metabase.com)")))
-    (is (= "<https://metabase.com|*Metabase*>" (mrkdwn "[__Metabase__](https://metabase.com)")))
-    (is (= "<https://metabase.com|`Metabase`>" (mrkdwn "[`Metabase`](https://metabase.com)"))))
+    (is (= "<https://metabase.com|Metabase>"   (slack "[Metabase](https://metabase.com)")))
+    (is (= "<https://metabase.com|Metabase>"   (slack "[Metabase](https://metabase.com \"tooltip\")")))
+    (is (= "<https://metabase.com|_Metabase_>" (slack "[*Metabase*](https://metabase.com)")))
+    (is (= "<https://metabase.com|_Metabase_>" (slack "[_Metabase_](https://metabase.com)")))
+    (is (= "<https://metabase.com|*Metabase*>" (slack "[**Metabase**](https://metabase.com)")))
+    (is (= "<https://metabase.com|*Metabase*>" (slack "[__Metabase__](https://metabase.com)")))
+    (is (= "<https://metabase.com|`Metabase`>" (slack "[`Metabase`](https://metabase.com)"))))
 
   (testing "Relative links are resolved to the current site URL"
     (tu/with-temporary-setting-values [site-url "https://example.com"]
-      (is (= "<https://example.com/foo|Metabase>"   (mrkdwn "[Metabase](/foo)")))))
+      (is (= "<https://example.com/foo|Metabase>"   (slack "[Metabase](/foo)")))))
 
   (testing "Auto-links are preserved"
-    (is (= "<http://metabase.com>"                        (mrkdwn "<http://metabase.com>")))
-    (is (= "<mailto:test@metabase.com>"                   (mrkdwn "<mailto:test@metabase.com>")))
-    (is (= "<mailto:test@metabase.com|test@metabase.com>" (mrkdwn "<test@metabase.com>"))))
+    (is (= "<http://metabase.com>"                        (slack "<http://metabase.com>")))
+    (is (= "<mailto:test@metabase.com>"                   (slack "<mailto:test@metabase.com>")))
+    (is (= "<mailto:test@metabase.com|test@metabase.com>" (slack "<test@metabase.com>"))))
 
   (testing "Bare URLs and email addresses are parsed as links"
-    (is (= "<https://metabase.com>"                       (mrkdwn "https://metabase.com")))
-    (is (= "<mailto:test@metabase.com|test@metabase.com>" (mrkdwn "test@metabase.com"))))
+    (is (= "<https://metabase.com>"                       (slack "https://metabase.com")))
+    (is (= "<mailto:test@metabase.com|test@metabase.com>" (slack "test@metabase.com"))))
 
   (testing "Link references render as normal links"
-    (is (= "<https://metabase.com|metabase>" (mrkdwn "[metabase]: https://metabase.com\n[metabase]")))
-    (is (= "<https://metabase.com|Metabase>" (mrkdwn "[Metabase]: https://metabase.com\n[Metabase]")))
-    (is (= "<https://metabase.com|Metabase>" (mrkdwn "[METABASE]: https://metabase.com\n[Metabase]")))
-    (is (= "<https://metabase.com|Metabase>" (mrkdwn "[Metabase]: https://metabase.com \"tooltip\"\n[Metabase]"))))
+    (is (= "<https://metabase.com|metabase>" (slack "[metabase]: https://metabase.com\n[metabase]")))
+    (is (= "<https://metabase.com|Metabase>" (slack "[Metabase]: https://metabase.com\n[Metabase]")))
+    (is (= "<https://metabase.com|Metabase>" (slack "[METABASE]: https://metabase.com\n[Metabase]")))
+    (is (= "<https://metabase.com|Metabase>" (slack "[Metabase]: https://metabase.com \"tooltip\"\n[Metabase]"))))
 
   (testing "Lists are rendered correctly using raw text"
-    (is (= "• foo\n• bar"   (mrkdwn "* foo\n* bar")))
-    (is (= "• foo\n• bar"   (mrkdwn "- foo\n- bar")))
-    (is (= "• foo\n• bar"   (mrkdwn "+ foo\n+ bar")))
-    (is (= "1. foo\n2. bar" (mrkdwn "1. foo\n2. bar")))
-    (is (= "1. foo\n2. bar" (mrkdwn "1. foo\n1. bar"))))
+    (is (= "• foo\n• bar"   (slack "* foo\n* bar")))
+    (is (= "• foo\n• bar"   (slack "- foo\n- bar")))
+    (is (= "• foo\n• bar"   (slack "+ foo\n+ bar")))
+    (is (= "1. foo\n2. bar" (slack "1. foo\n2. bar")))
+    (is (= "1. foo\n2. bar" (slack "1. foo\n1. bar"))))
 
   (testing "Nested lists are rendered correctly"
-    (is (= "1. foo\n    1. bar"                     (mrkdwn "1. foo\n   1. bar")))
-    (is (= "• foo\n    • bar"                       (mrkdwn "* foo\n   * bar")))
-    (is (= "1. foo\n    • bar"                      (mrkdwn "1. foo\n   * bar")))
-    (is (= "• foo\n    1. bar"                      (mrkdwn "* foo\n   1. bar")))
-    (is (= "• foo\n    1. bar\n    2. baz"          (mrkdwn "* foo\n   1. bar\n   2. baz")))
-    (is (= "• foo\n    1. bar\n• baz"               (mrkdwn "* foo\n   1. bar\n* baz")))
-    (is (= "• foo\n    >quote"                      (mrkdwn "* foo\n   >quote")))
-    (is (= "• foo\n    ```\n    codeblock\n    ```" (mrkdwn "* foo\n    ```\n    codeblock\n    ```"))))
+    (is (= "1. foo\n    1. bar"                     (slack "1. foo\n   1. bar")))
+    (is (= "• foo\n    • bar"                       (slack "* foo\n   * bar")))
+    (is (= "1. foo\n    • bar"                      (slack "1. foo\n   * bar")))
+    (is (= "• foo\n    1. bar"                      (slack "* foo\n   1. bar")))
+    (is (= "• foo\n    1. bar\n    2. baz"          (slack "* foo\n   1. bar\n   2. baz")))
+    (is (= "• foo\n    1. bar\n• baz"               (slack "* foo\n   1. bar\n* baz")))
+    (is (= "• foo\n    >quote"                      (slack "* foo\n   >quote")))
+    (is (= "• foo\n    ```\n    codeblock\n    ```" (slack "* foo\n    ```\n    codeblock\n    ```"))))
 
   (testing "Characters that are escaped in Markdown are preserved as plain text"
-    (is (= "\\" (mrkdwn "\\\\")))
-    (is (= "/"  (mrkdwn "\\/")))
-    (is (= "'"  (mrkdwn "\\'")))
-    (is (= "["  (mrkdwn "\\[")))
-    (is (= "]"  (mrkdwn "\\]")))
-    (is (= "("  (mrkdwn "\\(")))
-    (is (= ")"  (mrkdwn "\\)")))
-    (is (= "{"  (mrkdwn "\\{")))
-    (is (= "}"  (mrkdwn "\\}")))
-    (is (= "#"  (mrkdwn "\\#")))
-    (is (= "+"  (mrkdwn "\\+")))
-    (is (= "-"  (mrkdwn "\\-")))
-    (is (= "."  (mrkdwn "\\.")))
-    (is (= "!"  (mrkdwn "\\!")))
-    (is (= "$"  (mrkdwn "\\$")))
-    (is (= "%"  (mrkdwn "\\%")))
-    (is (= "^"  (mrkdwn "\\^")))
-    (is (= "="  (mrkdwn "\\=")))
-    (is (= "|"  (mrkdwn "\\|")))
-    (is (= "?"  (mrkdwn "\\?"))))
+    (is (= "\\" (slack "\\\\")))
+    (is (= "/"  (slack "\\/")))
+    (is (= "'"  (slack "\\'")))
+    (is (= "["  (slack "\\[")))
+    (is (= "]"  (slack "\\]")))
+    (is (= "("  (slack "\\(")))
+    (is (= ")"  (slack "\\)")))
+    (is (= "{"  (slack "\\{")))
+    (is (= "}"  (slack "\\}")))
+    (is (= "#"  (slack "\\#")))
+    (is (= "+"  (slack "\\+")))
+    (is (= "-"  (slack "\\-")))
+    (is (= "."  (slack "\\.")))
+    (is (= "!"  (slack "\\!")))
+    (is (= "$"  (slack "\\$")))
+    (is (= "%"  (slack "\\%")))
+    (is (= "^"  (slack "\\^")))
+    (is (= "="  (slack "\\=")))
+    (is (= "|"  (slack "\\|")))
+    (is (= "?"  (slack "\\?"))))
 
   (testing "Certain characters that are escaped in Markdown are surrounded by zero-width characters for Slack"
-    (is (= "\u00ad&\u00ad" (mrkdwn "\\&")))
-    (is (= "\u00ad>\u00ad" (mrkdwn "\\>")))
-    (is (= "\u00ad<\u00ad" (mrkdwn "\\<")))
-    (is (= "\u00ad*\u00ad" (mrkdwn "\\*")))
-    (is (= "\u00ad_\u00ad" (mrkdwn "\\_")))
-    (is (= "\u00ad`\u00ad" (mrkdwn "\\`"))))
+    (is (= "\u00ad&\u00ad" (slack "\\&")))
+    (is (= "\u00ad>\u00ad" (slack "\\>")))
+    (is (= "\u00ad<\u00ad" (slack "\\<")))
+    (is (= "\u00ad*\u00ad" (slack "\\*")))
+    (is (= "\u00ad_\u00ad" (slack "\\_")))
+    (is (= "\u00ad`\u00ad" (slack "\\`"))))
 
   (testing "Images in Markdown are converted to links, with alt text preserved"
-    (is (= "<image.png|[Image]>"           (mrkdwn "![](image.png)")))
-    (is (= "<image.png|[Image: alt-text]>" (mrkdwn "![alt-text](image.png)"))))
+    (is (= "<image.png|[Image]>"           (slack "![](image.png)")))
+    (is (= "<image.png|[Image: alt-text]>" (slack "![alt-text](image.png)"))))
 
   (testing "Image references are treated the same as normal images"
-    (is (=  "<image.png|[Image]>"           (mrkdwn "![][ref]\n\n[ref]: image.png")))
-    (is (=  "<image.png|[Image: alt-text]>" (mrkdwn "![alt-text][ref]\n\n[ref]: image.png")))
-    (is (=  "<image.png|[Image]>"           (mrkdwn "![][Ref]\n\n[REF]: image.png"))))
+    (is (=  "<image.png|[Image]>"           (slack "![][ref]\n\n[ref]: image.png")))
+    (is (=  "<image.png|[Image: alt-text]>" (slack "![alt-text][ref]\n\n[ref]: image.png")))
+    (is (=  "<image.png|[Image]>"           (slack "![][Ref]\n\n[REF]: image.png"))))
 
   (testing "Linked images include link target in parentheses"
-    (is (= "<image.png|[Image]>\n(https://metabase.com)"  (mrkdwn "[![](image.png)](https://metabase.com)")))
-    (is (=  "<image.png|[Image]>\n(https://metabase.com)" (mrkdwn "[![][ref]](https://metabase.com)\n\n[ref]: image.png"))))
+    (is (= "<image.png|[Image]>\n(https://metabase.com)"  (slack "[![](image.png)](https://metabase.com)")))
+    (is (=  "<image.png|[Image]>\n(https://metabase.com)" (slack "[![][ref]](https://metabase.com)\n\n[ref]: image.png"))))
 
   (testing "Raw HTML in Markdown is passed through unmodified, aside from angle brackets being
            escaped with zero-width characters"
-    (is (= (escape "<h1>header</h1>")              (mrkdwn "<h1>header</h1>")))
-    (is (= (escape "<em>bold</em>")                (mrkdwn "<em>bold</em>")))
-    (is (= (escape "<body><h1>header</h1></body>") (mrkdwn "<body><h1>header</h1></body>")))
-    (is (= (escape "<p>&gt;</p>")                  (mrkdwn "<p>&gt;</p>")))
-    (is (= (escape "<img src=\"img.png\" />")      (mrkdwn "<img src=\"img.png\" />")))
-    (is (= (escape "<script>alert(1)</script>")    (mrkdwn "<script>alert(1)</script>")))
-    (is (= (escape "<h1><!-- comment --></h1>")    (mrkdwn "<h1><!-- comment --></h1>")))
-    (is (= (escape "<em><!-- comment --></em>")    (mrkdwn "<em><!-- comment --></em>")))
-    (is (= (escape "<!-- <p>comm\nent</p> -->")    (mrkdwn "<!-- <p>comm\nent</p> -->")))
-    (is (= (escape "<!-- <p>comm\nent</p> -->")    (mrkdwn "<!-- <p>comm\nent</p> -->")))
-    (is (= (escape "<!DOCTYPE html>")              (mrkdwn "<!DOCTYPE html>"))))
+    (is (= (escape "<h1>header</h1>")              (slack "<h1>header</h1>")))
+    (is (= (escape "<em>bold</em>")                (slack "<em>bold</em>")))
+    (is (= (escape "<body><h1>header</h1></body>") (slack "<body><h1>header</h1></body>")))
+    (is (= (escape "<p>&gt;</p>")                  (slack "<p>&gt;</p>")))
+    (is (= (escape "<img src=\"img.png\" />")      (slack "<img src=\"img.png\" />")))
+    (is (= (escape "<script>alert(1)</script>")    (slack "<script>alert(1)</script>")))
+    (is (= (escape "<h1><!-- comment --></h1>")    (slack "<h1><!-- comment --></h1>")))
+    (is (= (escape "<em><!-- comment --></em>")    (slack "<em><!-- comment --></em>")))
+    (is (= (escape "<!-- <p>comm\nent</p> -->")    (slack "<!-- <p>comm\nent</p> -->")))
+    (is (= (escape "<!-- <p>comm\nent</p> -->")    (slack "<!-- <p>comm\nent</p> -->")))
+    (is (= (escape "<!DOCTYPE html>")              (slack "<!DOCTYPE html>"))))
 
   (testing "HTML entities (outside of HTML tags) are converted to Unicode"
-    (is (= "&" (mrkdwn "&amp;")))
-    (is (= ">" (mrkdwn "&gt;")))
-    (is (= "ℋ" (mrkdwn "&HilbertSpace;"))))
+    (is (= "&" (slack "&amp;")))
+    (is (= ">" (slack "&gt;")))
+    (is (= "ℋ" (slack "&HilbertSpace;"))))
 
   (testing "Square brackets that aren't used for a link are left as-is (#20993)"
-    (is (= "[]"     (mrkdwn "[]")))
-    (is (= "[test]" (mrkdwn "[test]")))))
+    (is (= "[]"     (slack "[]")))
+    (is (= "[test]" (slack "[test]")))))
 
 (defn- html
   [markdown]