Add .cheatmd to epub to avoid broken links

Closes elixir-lang/elixir#14753.

Author: josevalim

lib/ex_doc/formatter/epub.ex

@@ -63,7 +63,7 @@ defmodule ExDoc.Formatter.EPUB do
   defp generate_extras(config) do
     for {_title, extras} <- config.extras,
         node <- extras,
-        not is_map_key(node, :url) and node.type != :cheatmd do
+        not is_map_key(node, :url) do
       output = "#{config.output}/OEBPS/#{node.id}.xhtml"
       html = Templates.extra_template(config, node)
 

test/ex_doc/formatter/epub_test.exs

@@ -126,22 +126,66 @@ defmodule ExDoc.Formatter.EPUBTest do
     assert content =~ ~r{.*"Mix\.Tasks\.TaskWithDocs\".*}ms
   end
 
-  test "generates the readme file", %{tmp_dir: tmp_dir} = context do
+  test "generates the readme file as main", %{tmp_dir: tmp_dir} = context do
     config = doc_config(context, main: "README", extras: ["test/fixtures/README.md"])
     generate_docs_and_unzip(context, config)
 
-    content = File.read!(tmp_dir <> "/epub/OEBPS/readme.xhtml")
-    assert content =~ ~r{<title>README [^<]*</title>}
-    assert content =~ ~r{<a href="RandomError.xhtml"><code(\sclass="inline")?>RandomError</code>}
+    content = File.read!(tmp_dir <> "/epub/OEBPS/nav.xhtml")
+    assert content =~ ~r{<li><a href="readme.xhtml">README</a></li>}
+  end
+
+  test "generates extras", %{tmp_dir: tmp_dir} = context do
+    config =
+      doc_config(context,
+        extras: [
+          "test/fixtures/LICENSE",
+          "test/fixtures/PlainText.txt",
+          "test/fixtures/PlainTextFiles.md",
+          "test/fixtures/README.md",
+          "test/fixtures/LivebookFile.livemd",
+          "test/fixtures/cheatsheets.cheatmd"
+        ]
+      )
+
+    generate_docs_and_unzip(context, config)
+
+    content = File.read!(tmp_dir <> "/epub/OEBPS/plaintextfiles.xhtml")
+
+    assert content =~ ~r{Plain Text Files</h1>}s
 
     assert content =~
-             ~r{<a href="CustomBehaviourImpl.xhtml#hello/1"><code(\sclass="inline")?>CustomBehaviourImpl.hello/1</code>}
+             ~r{<p>Read the <a href="license.xhtml">license</a> and the <a href="plaintext.xhtml">plain-text file</a>.}
+
+    plain_text_file = File.read!(tmp_dir <> "/epub/OEBPS/plaintext.xhtml")
+
+    assert plain_text_file =~ ~r{PlainText</h1>}s
+
+    assert plain_text_file =~
+             ~r{<pre>\nThis is plain\n  text and nothing\n.+\s+good bye\n</pre>}s
+
+    assert plain_text_file =~ ~s{\n## Neither formatted\n}
+    assert plain_text_file =~ ~s{\n      `t:term/0`\n}
+
+    license = File.read!(tmp_dir <> "/epub/OEBPS/license.xhtml")
+
+    assert license =~ ~r{LICENSE</h1>}s
+
+    assert license =~
+             ~s{<pre>\nLicensed under the Apache License, Version 2.0 (the &quot;License&quot;)}
+
+    content = File.read!(tmp_dir <> "/epub/OEBPS/livebookfile.xhtml")
+
+    assert content =~ ~r{Title for Livebook Files</h1>}
 
     assert content =~
-             ~r{<a href="TypesAndSpecs.Sub.xhtml"><code(\sclass="inline")?>TypesAndSpecs.Sub</code></a>}
+             ~s{<p>Read <code class="inline">.livemd</code> files generated by <a href="https://github.com/livebook-dev/livebook">livebook</a>.}
 
-    content = File.read!(tmp_dir <> "/epub/OEBPS/nav.xhtml")
-    assert content =~ ~r{<li><a href="readme.xhtml">README</a></li>}
+    content = File.read!(tmp_dir <> "/epub/OEBPS/cheatsheets.xhtml")
+
+    assert content =~ ~s{<h2 id="getting-started">}
+    assert content =~ ~s{<h3 id="hello-world">}
+    assert content =~ ~s{<h2 id="types">}
+    assert content =~ ~s{<h3 id="operators">}
   end
 
   test "ignores any external url extras", %{tmp_dir: tmp_dir} = context do