Discard mermaid fenced blocks from ansi docs

Author: josevalim

lib/elixir/lib/io/ansi/docs.ex

@@ -176,12 +176,17 @@ defmodule IO.ANSI.Docs do
     process_code(rest, [line], indent, options)
   end
 
-  defp process(["```" <> _line | rest], text, indent, options) do
-    process_fenced_code_block(rest, text, indent, options, _delimiter = "```")
+  defp process(["```mermaid" <> _line | rest], text, indent, options) do
+    write_text(text, indent, options)
+
+    rest
+    |> Enum.drop_while(&(&1 != "```"))
+    |> Enum.drop(1)
+    |> process([], indent, options)
   end
 
-  defp process(["~~~" <> _line | rest], text, indent, options) do
-    process_fenced_code_block(rest, text, indent, options, _delimiter = "~~~")
+  defp process(["```" <> _line | rest], text, indent, options) do
+    process_fenced_code_block(rest, text, indent, options, _delimiter = "```")
   end
 
   defp process(["<!--" <> line | rest], text, indent, options) do
@@ -388,7 +393,7 @@ defmodule IO.ANSI.Docs do
   end
 
   defp process_fenced_code([line | rest], code, indent, options, delimiter) do
-    if line === delimiter do
+    if line == delimiter do
       process_code(rest, code, indent, options)
     else
       process_fenced_code(rest, [line | code], indent, options, delimiter)

lib/elixir/test/elixir/io/ansi/docs_test.exs

@@ -187,8 +187,11 @@ defmodule IO.ANSI.DocsTest do
       assert result == "line\n\e[0m\n\e[36m    code\n    code2\e[0m\n\e[0m\nline2\n\e[0m"
       result = format_markdown("line\n```elixir\ncode\ncode2\n```\nline2\n")
       assert result == "line\n\e[0m\n\e[36m    code\n    code2\e[0m\n\e[0m\nline2\n\e[0m"
-      result = format_markdown("line\n~~~elixir\ncode\n```\n~~~\nline2\n")
-      assert result == "line\n\e[0m\n\e[36m    code\n    ```\e[0m\n\e[0m\nline2\n\e[0m"
+    end
+
+    test "mermaid fenced code block is discarded" do
+      result = format_markdown("line\n```mermaid\ncode\ncode2\n```\nline2\n")
+      assert result == "line\n\e[0m\nline2\n\e[0m"
     end
 
     test "* list is converted" do