diff --git a/.gitignore b/.gitignore
index 9f8e27862..1a2bf195c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,6 +25,7 @@ ex_doc-*.tar
 node_modules/
 /test/fixtures/umbrella/_build/
 /test/tmp/
+/tmp/
 /npm-debug.log
 
 # Ignore artifacts from non-production builds
diff --git a/test/ex_doc/formatter/epub_test.exs b/test/ex_doc/formatter/epub_test.exs
index eca1ad1e2..7d38a36c0 100644
--- a/test/ex_doc/formatter/epub_test.exs
+++ b/test/ex_doc/formatter/epub_test.exs
@@ -1,18 +1,7 @@
 defmodule ExDoc.Formatter.EPUBTest do
-  use ExUnit.Case
+  use ExUnit.Case, async: true
 
-  setup do
-    File.rm_rf(output_dir())
-    File.mkdir_p!(output_dir())
-  end
-
-  defp output_dir do
-    Path.expand("../../tmp/epub", __DIR__)
-  end
-
-  defp beam_dir do
-    Path.expand("../../tmp/beam", __DIR__)
-  end
+  @moduletag :tmp_dir
 
   @before_closing_head_tag_content_epub "UNIQUE:<dont-escape>&copy;BEFORE-CLOSING-HEAD-TAG-HTML</dont-escape>"
   @before_closing_body_tag_content_epub "UNIQUE:<dont-escape>&copy;BEFORE-CLOSING-BODY-TAG-HTML</dont-escape>"
@@ -20,95 +9,95 @@ defmodule ExDoc.Formatter.EPUBTest do
   defp before_closing_head_tag(:epub), do: @before_closing_head_tag_content_epub
   defp before_closing_body_tag(:epub), do: @before_closing_body_tag_content_epub
 
-  defp doc_config do
+  defp doc_config(%{tmp_dir: tmp_dir} = _context) do
     [
       app: :elixir,
       project: "Elixir",
       version: "1.0.1",
       formatter: "epub",
-      output: output_dir(),
-      source_beam: beam_dir(),
+      output: tmp_dir <> "/epub",
+      source_beam: "test/tmp/beam",
       extras: ["test/fixtures/README.md"],
       skip_undefined_reference_warnings_on: ["Warnings"]
     ]
   end
 
-  defp doc_config(config) do
-    Keyword.merge(doc_config(), config)
+  defp doc_config(context, config) when is_map(context) and is_list(config) do
+    Keyword.merge(doc_config(context), config)
   end
 
   defp generate_docs(config) do
     ExDoc.generate_docs(config[:project], config[:version], config)
   end
 
-  defp generate_docs_and_unzip(options) do
-    generate_docs(options)
-    unzip_dir = String.to_charlist("#{doc_config()[:output]}")
+  defp generate_docs_and_unzip(context, config) do
+    generate_docs(config)
+    unzip_dir = String.to_charlist("#{doc_config(context)[:output]}")
 
-    "#{doc_config()[:output]}/#{doc_config()[:project]}.epub"
+    "#{doc_config(context)[:output]}/#{doc_config(context)[:project]}.epub"
     |> String.to_charlist()
     |> :zip.unzip(cwd: unzip_dir)
   end
 
-  test "generates headers for module pages" do
-    generate_docs_and_unzip(doc_config(main: "RandomError"))
+  test "generates headers for module pages", %{tmp_dir: tmp_dir} = context do
+    generate_docs_and_unzip(context, doc_config(context, main: "RandomError"))
 
-    content = File.read!("#{output_dir()}/OEBPS/RandomError.xhtml")
+    content = File.read!(tmp_dir <> "/epub/OEBPS/RandomError.xhtml")
     assert content =~ ~r{<html.*lang="en".*xmlns:epub="http://www.idpf.org/2007/ops">}ms
     assert content =~ ~r{<meta charset="utf-8" />}ms
     assert content =~ ~r{<meta name="generator" content="ExDoc v[^"]+" />}
     assert content =~ ~r{<title>RandomError - Elixir v1.0.1</title>}
   end
 
-  test "allows to set the primary language of the document" do
-    generate_docs_and_unzip(doc_config(main: "RandomError", language: "fr"))
+  test "allows to set the primary language of the document", %{tmp_dir: tmp_dir} = context do
+    generate_docs_and_unzip(context, doc_config(context, main: "RandomError", language: "fr"))
 
-    content = File.read!("#{output_dir()}/OEBPS/RandomError.xhtml")
+    content = File.read!(tmp_dir <> "/epub/OEBPS/RandomError.xhtml")
     assert content =~ ~r{<html.*lang="fr".*xmlns:epub="http://www.idpf.org/2007/ops">}ms
   end
 
-  test "allows to set the authors of the book" do
-    generate_docs_and_unzip(doc_config(authors: ["John Doe", "Jane Doe"]))
+  test "allows to set the authors of the book", %{tmp_dir: tmp_dir} = context do
+    generate_docs_and_unzip(context, doc_config(context, authors: ["John Doe", "Jane Doe"]))
 
-    content = File.read!("#{output_dir()}/OEBPS/content.opf")
+    content = File.read!(tmp_dir <> "/epub/OEBPS/content.opf")
     assert content =~ ~r{<dc:creator id="author1">John Doe</dc:creator>}
     assert content =~ ~r{<dc:creator id="author2">Jane Doe</dc:creator>}
   end
 
-  test "raises when assets are invalid" do
+  test "raises when assets are invalid", context do
     File.mkdir_p!("test/tmp/epub_assets/hello")
     File.touch!("test/tmp/epub_assets/hello/world.pdf")
 
     assert_raise(
       RuntimeError,
       ~s{asset with extension ".pdf" is not supported by EPUB format},
-      fn -> generate_docs(doc_config(assets: "test/tmp/epub_assets")) end
+      fn -> generate_docs(doc_config(context, assets: "test/tmp/epub_assets")) end
     )
   after
     File.rm_rf!("test/tmp/epub_assets")
   end
 
-  test "generates an EPUB file in the default directory" do
-    generate_docs(doc_config())
-    assert File.regular?("#{output_dir()}/#{doc_config()[:project]}.epub")
+  test "generates an EPUB file in the default directory", %{tmp_dir: tmp_dir} = context do
+    generate_docs(doc_config(context))
+    assert File.regular?(tmp_dir <> "/epub/#{doc_config(context)[:project]}.epub")
   end
 
-  test "generates an EPUB file with erlang as proglang" do
-    generate_docs(Keyword.put(doc_config(), :proglang, :erlang))
-    assert File.regular?("#{output_dir()}/#{doc_config()[:project]}.epub")
+  test "generates an EPUB file with erlang as proglang", %{tmp_dir: tmp_dir} = context do
+    generate_docs(Keyword.put(doc_config(context), :proglang, :erlang))
+    assert File.regular?(tmp_dir <> "/epub/#{doc_config(context)[:project]}.epub")
   end
 
-  test "generates an EPUB file in specified output directory" do
-    config = doc_config(output: "#{output_dir()}/another_dir", main: "RandomError")
+  test "generates an EPUB file in specified output directory", %{tmp_dir: tmp_dir} = context do
+    config = doc_config(context, output: tmp_dir <> "/epub/another_dir", main: "RandomError")
     generate_docs(config)
 
-    assert File.regular?("#{output_dir()}/another_dir/#{doc_config()[:project]}.epub")
+    assert File.regular?(tmp_dir <> "/epub/another_dir/#{doc_config(context)[:project]}.epub")
   end
 
-  test "generates an EPUB file with a standardized structure" do
-    generate_docs_and_unzip(doc_config())
+  test "generates an EPUB file with a standardized structure", %{tmp_dir: tmp_dir} = context do
+    generate_docs_and_unzip(context, doc_config(context))
 
-    root_dir = "#{output_dir()}"
+    root_dir = tmp_dir <> "/epub"
     meta_dir = "#{root_dir}/META-INF"
     oebps_dir = "#{root_dir}/OEBPS"
     dist_dir = "#{oebps_dir}/dist"
@@ -126,9 +115,9 @@ defmodule ExDoc.Formatter.EPUBTest do
     assert [_] = Path.wildcard("#{dist_dir}/elixir*.css")
   end
 
-  test "generates all listing files" do
-    generate_docs_and_unzip(doc_config())
-    content = File.read!("#{output_dir()}/OEBPS/content.opf")
+  test "generates all listing files", %{tmp_dir: tmp_dir} = context do
+    generate_docs_and_unzip(context, doc_config(context))
+    content = File.read!(tmp_dir <> "/epub/OEBPS/content.opf")
 
     assert content =~ ~r{.*"CompiledWithDocs\".*}ms
     assert content =~ ~r{.*"CompiledWithDocs.Nested\".*}ms
@@ -139,11 +128,11 @@ defmodule ExDoc.Formatter.EPUBTest do
     assert content =~ ~r{.*"Mix\.Tasks\.TaskWithDocs\".*}ms
   end
 
-  test "generates the readme file" do
-    config = doc_config(main: "README")
-    generate_docs_and_unzip(config)
+  test "generates the readme file", %{tmp_dir: tmp_dir} = context do
+    config = doc_config(context, main: "README")
+    generate_docs_and_unzip(context, config)
 
-    content = File.read!("#{output_dir()}/OEBPS/readme.xhtml")
+    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>}
 
@@ -153,14 +142,14 @@ defmodule ExDoc.Formatter.EPUBTest do
     assert content =~
              ~r{<a href="TypesAndSpecs.Sub.xhtml"><code(\sclass="inline")?>TypesAndSpecs.Sub</code></a>}
 
-    content = File.read!("#{output_dir()}/OEBPS/nav.xhtml")
+    content = File.read!(tmp_dir <> "/epub/OEBPS/nav.xhtml")
     assert content =~ ~r{<li><a href="readme.xhtml">README</a></li>}
   end
 
-  test "uses samp as highlight tag for markdown" do
-    generate_docs_and_unzip(doc_config())
+  test "uses samp as highlight tag for markdown", %{tmp_dir: tmp_dir} = context do
+    generate_docs_and_unzip(context, doc_config(context))
 
-    assert File.read!("#{output_dir()}/OEBPS/CompiledWithDocs.xhtml") =~
+    assert File.read!(tmp_dir <> "/epub/OEBPS/CompiledWithDocs.xhtml") =~
              "<samp class=\"nc\">CompiledWithDocs<\/samp>"
   end
 
@@ -174,15 +163,17 @@ defmodule ExDoc.Formatter.EPUBTest do
     "CompiledWithDocs.Nested.xhtml"
   ]
 
-  test "before_closing_*_tags required by the user are in the right place" do
+  test "before_closing_*_tags required by the user are in the right place",
+       %{tmp_dir: tmp_dir} = context do
     generate_docs_and_unzip(
-      doc_config(
+      context,
+      doc_config(context,
         before_closing_head_tag: &before_closing_head_tag/1,
         before_closing_body_tag: &before_closing_body_tag/1
       )
     )
 
-    oebps_dir = "#{output_dir()}/OEBPS"
+    oebps_dir = tmp_dir <> "/epub/OEBPS"
 
     for basename <- @example_basenames do
       content = File.read!(Path.join(oebps_dir, basename))
@@ -191,21 +182,22 @@ defmodule ExDoc.Formatter.EPUBTest do
     end
   end
 
-  test "assets required by the user end up in the right place" do
+  test "assets required by the user end up in the right place", %{tmp_dir: tmp_dir} = context do
     File.mkdir_p!("test/tmp/epub_assets/hello")
     File.touch!("test/tmp/epub_assets/hello/world.png")
 
     generate_docs_and_unzip(
-      doc_config(
+      context,
+      doc_config(context,
         assets: "test/tmp/epub_assets",
         logo: "test/fixtures/elixir.png",
         cover: "test/fixtures/elixir.png"
       )
     )
 
-    assert File.regular?("#{output_dir()}/OEBPS/assets/hello/world.png")
-    assert File.regular?("#{output_dir()}/OEBPS/assets/logo.png")
-    assert File.regular?("#{output_dir()}/OEBPS/assets/cover.png")
+    assert File.regular?(tmp_dir <> "/epub/OEBPS/assets/hello/world.png")
+    assert File.regular?(tmp_dir <> "/epub/OEBPS/assets/logo.png")
+    assert File.regular?(tmp_dir <> "/epub/OEBPS/assets/cover.png")
   after
     File.rm_rf!("test/tmp/epub_assets")
   end
diff --git a/test/ex_doc/formatter/html_test.exs b/test/ex_doc/formatter/html_test.exs
index fd7b891f9..00fc51ad4 100644
--- a/test/ex_doc/formatter/html_test.exs
+++ b/test/ex_doc/formatter/html_test.exs
@@ -1,21 +1,10 @@
 defmodule ExDoc.Formatter.HTMLTest do
-  use ExUnit.Case
+  use ExUnit.Case, async: true
 
   import ExUnit.CaptureIO
   alias ExDoc.Formatter.HTML
 
-  setup do
-    File.rm_rf(output_dir())
-    File.mkdir_p!(output_dir())
-  end
-
-  defp output_dir do
-    Path.expand("../../tmp/html", __DIR__)
-  end
-
-  defp beam_dir do
-    Path.expand("../../tmp/beam", __DIR__)
-  end
+  @moduletag :tmp_dir
 
   defp read_wildcard!(path) do
     [file] = Path.wildcard(path)
@@ -28,23 +17,23 @@ defmodule ExDoc.Formatter.HTMLTest do
   defp before_closing_head_tag(:html), do: @before_closing_head_tag_content_html
   defp before_closing_body_tag(:html), do: @before_closing_body_tag_content_html
 
-  defp doc_config do
+  defp doc_config(%{tmp_dir: tmp_dir} = _context) do
     [
       apps: [:elixir],
       project: "Elixir",
       version: "1.0.1",
       formatter: "html",
       assets: "test/tmp/html_assets",
-      output: output_dir(),
-      source_beam: beam_dir(),
+      output: tmp_dir <> "/html",
+      source_beam: "test/tmp/beam",
       source_url: "https://github.com/elixir-lang/elixir",
       logo: "test/fixtures/elixir.png",
       extras: []
     ]
   end
 
-  defp doc_config(config) do
-    Keyword.merge(doc_config(), config)
+  defp doc_config(context, config) when is_map(context) and is_list(config) do
+    Keyword.merge(doc_config(context), config)
   end
 
   defp generate_docs(config) do
@@ -52,17 +41,17 @@ defmodule ExDoc.Formatter.HTMLTest do
     ExDoc.generate_docs(config[:project], config[:version], config)
   end
 
-  test "normalizes options" do
+  test "normalizes options", %{tmp_dir: tmp_dir} = context do
     # 1. Check for output dir having trailing "/" stripped
     # 2. Check for default [main: "api-reference"]
-    generate_docs(doc_config(output: "#{output_dir()}//", main: nil))
+    generate_docs(doc_config(context, output: tmp_dir <> "/html//", main: nil))
 
-    content = File.read!("#{output_dir()}/index.html")
+    content = File.read!(tmp_dir <> "/html/index.html")
     assert content =~ ~r{<meta http-equiv="refresh" content="0; url=api-reference.html">}
-    assert File.regular?("#{output_dir()}/api-reference.html")
+    assert File.regular?(tmp_dir <> "/html/api-reference.html")
 
     # 3. main as index is not allowed
-    config = doc_config(main: "index")
+    config = doc_config(context, main: "index")
 
     assert_raise ArgumentError,
                  ~S("main" cannot be set to "index", otherwise it will recursively link to itself),
@@ -91,21 +80,22 @@ defmodule ExDoc.Formatter.HTMLTest do
     end
   end
 
-  test "warns when generating an index.html file with an invalid redirect" do
+  test "warns when generating an index.html file with an invalid redirect",
+       %{tmp_dir: tmp_dir} = context do
     output =
       capture_io(:stderr, fn ->
-        generate_docs(doc_config(main: "Randomerror"))
+        generate_docs(doc_config(context, main: "Randomerror"))
       end)
 
     assert output == "warning: index.html redirects to Randomerror.html, which does not exist\n"
-    assert File.regular?("#{output_dir()}/index.html")
-    assert File.regular?("#{output_dir()}/RandomError.html")
+    assert File.regular?(tmp_dir <> "/html/index.html")
+    assert File.regular?(tmp_dir <> "/html/RandomError.html")
   end
 
-  test "warns on undefined functions" do
+  test "warns on undefined functions", context do
     output =
       capture_io(:stderr, fn ->
-        generate_docs(doc_config(skip_undefined_reference_warnings_on: []))
+        generate_docs(doc_config(context, skip_undefined_reference_warnings_on: []))
       end)
 
     assert output =~ ~r"Warnings.bar/0.*\n  test/fixtures/warnings.ex:2: Warnings"
@@ -114,21 +104,21 @@ defmodule ExDoc.Formatter.HTMLTest do
     assert output =~ ~r"Warnings.bar/0.*\n  test/fixtures/warnings.ex:8: t:Warnings.t/0"
   end
 
-  test "warns on undefined functions in file" do
+  test "warns on undefined functions in file", context do
     output =
       capture_io(:stderr, fn ->
         generate_docs(
-          doc_config(skip_undefined_reference_warnings_on: ["test/fixtures/warnings.ex"])
+          doc_config(context, skip_undefined_reference_warnings_on: ["test/fixtures/warnings.ex"])
         )
       end)
 
     assert output == ""
   end
 
-  test "generates headers for index.html and module pages" do
-    generate_docs(doc_config(main: "RandomError"))
-    content_index = File.read!("#{output_dir()}/index.html")
-    content_module = File.read!("#{output_dir()}/RandomError.html")
+  test "generates headers for index.html and module pages", %{tmp_dir: tmp_dir} = context do
+    generate_docs(doc_config(context, main: "RandomError"))
+    content_index = File.read!(tmp_dir <> "/html/index.html")
+    content_module = File.read!(tmp_dir <> "/html/RandomError.html")
 
     # Regular Expressions
     re = %{
@@ -164,30 +154,31 @@ defmodule ExDoc.Formatter.HTMLTest do
     refute content_module =~ re[:index][:refresh]
   end
 
-  test "allows to set the authors of the document" do
-    generate_docs(doc_config(authors: ["John Doe", "Jane Doe"]))
-    content_index = File.read!("#{output_dir()}/api-reference.html")
+  test "allows to set the authors of the document", %{tmp_dir: tmp_dir} = context do
+    generate_docs(doc_config(context, authors: ["John Doe", "Jane Doe"]))
+    content_index = File.read!(tmp_dir <> "/html/api-reference.html")
 
     assert content_index =~ ~r{<meta name="author" content="John Doe, Jane Doe">}
   end
 
-  test "generates in default directory with redirect index.html file" do
-    generate_docs(doc_config())
+  test "generates in default directory with redirect index.html file",
+       %{tmp_dir: tmp_dir} = context do
+    generate_docs(doc_config(context))
 
-    assert File.regular?("#{output_dir()}/CompiledWithDocs.html")
-    assert File.regular?("#{output_dir()}/CompiledWithDocs.Nested.html")
+    assert File.regular?(tmp_dir <> "/html/CompiledWithDocs.html")
+    assert File.regular?(tmp_dir <> "/html/CompiledWithDocs.Nested.html")
 
-    assert [_] = Path.wildcard("#{output_dir()}/dist/app-*.js")
-    assert [_] = Path.wildcard("#{output_dir()}/dist/elixir-*.css")
+    assert [_] = Path.wildcard(tmp_dir <> "/html/dist/app-*.js")
+    assert [_] = Path.wildcard(tmp_dir <> "/html/dist/elixir-*.css")
 
-    content = File.read!("#{output_dir()}/index.html")
+    content = File.read!(tmp_dir <> "/html/index.html")
     assert content =~ ~r{<meta http-equiv="refresh" content="0; url=api-reference.html">}
   end
 
-  test "generates all listing files" do
-    generate_docs(doc_config())
+  test "generates all listing files", %{tmp_dir: tmp_dir} = context do
+    generate_docs(doc_config(context))
 
-    content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+    content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
     assert content =~ ~r{"id":"CompiledWithDocs",.*"title":"CompiledWithDocs"}ms
     assert content =~ ~r("id":"CompiledWithDocs",.*"key":"functions".*"example/2")ms
     assert content =~ ~r{"id":"CompiledWithDocs\.Nested",.*"title":"CompiledWithDocs\.Nested"}ms
@@ -199,10 +190,10 @@ defmodule ExDoc.Formatter.HTMLTest do
     assert content =~ ~r{"id":"Mix\.Tasks\.TaskWithDocs",.*"title":"mix task_with_docs"}ms
   end
 
-  test "generates the api reference file" do
-    generate_docs(doc_config())
+  test "generates the api reference file", %{tmp_dir: tmp_dir} = context do
+    generate_docs(doc_config(context))
 
-    content = File.read!("#{output_dir()}/api-reference.html")
+    content = File.read!(tmp_dir <> "/html/api-reference.html")
     assert content =~ ~r{<a href="CompiledWithDocs.html" translate="no">CompiledWithDocs</a>}
     assert content =~ ~r{<p>moduledoc</p>}
 
@@ -213,12 +204,12 @@ defmodule ExDoc.Formatter.HTMLTest do
              ~r{<a href="Mix.Tasks.TaskWithDocs.html" translate="no">mix task_with_docs</a>}
   end
 
-  test "groups modules by nesting" do
-    doc_config()
+  test "groups modules by nesting", %{tmp_dir: tmp_dir} = context do
+    doc_config(context)
     |> Keyword.put(:nest_modules_by_prefix, [Common.Nesting.Prefix.B, Common.Nesting.Prefix.B.B])
     |> generate_docs()
 
-    "sidebarNodes=" <> content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+    "sidebarNodes=" <> content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
     assert {:ok, %{"modules" => modules}} = Jason.decode(content)
 
     assert %{"nested_context" => "Common.Nesting.Prefix.B"} =
@@ -228,7 +219,7 @@ defmodule ExDoc.Formatter.HTMLTest do
              Enum.find(modules, fn %{"id" => id} -> id == "Common.Nesting.Prefix.B.B.A" end)
   end
 
-  test "groups modules by nesting respecting groups" do
+  test "groups modules by nesting respecting groups", %{tmp_dir: tmp_dir} = context do
     groups = [
       Group1: [
         Common.Nesting.Prefix.B.A,
@@ -240,12 +231,12 @@ defmodule ExDoc.Formatter.HTMLTest do
       ]
     ]
 
-    doc_config()
+    doc_config(context)
     |> Keyword.put(:nest_modules_by_prefix, [Common.Nesting.Prefix.B, Common.Nesting.Prefix.B.B])
     |> Keyword.put(:groups_for_modules, groups)
     |> generate_docs()
 
-    "sidebarNodes=" <> content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+    "sidebarNodes=" <> content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
     assert {:ok, %{"modules" => modules}} = Jason.decode(content)
 
     assert %{"Group1" => [_, _], "Group2" => [_, _]} =
@@ -253,15 +244,15 @@ defmodule ExDoc.Formatter.HTMLTest do
   end
 
   describe "generates logo" do
-    test "overriding previous entries" do
-      File.mkdir_p!("#{output_dir()}/assets")
-      File.touch!("#{output_dir()}/assets/logo.png")
-      generate_docs(doc_config(logo: "test/fixtures/elixir.png"))
-      assert File.read!("#{output_dir()}/assets/logo.png") != ""
+    test "overriding previous entries", %{tmp_dir: tmp_dir} = context do
+      File.mkdir_p!(tmp_dir <> "/html/assets")
+      File.touch!(tmp_dir <> "/html/assets/logo.png")
+      generate_docs(doc_config(context, logo: "test/fixtures/elixir.png"))
+      assert File.read!(tmp_dir <> "/html/assets/logo.png") != ""
     end
 
-    test "fails when logo is not an allowed format" do
-      config = doc_config(logo: "README.md")
+    test "fails when logo is not an allowed format", context do
+      config = doc_config(context, logo: "README.md")
 
       assert_raise ArgumentError,
                    "image format not recognized, allowed formats are: .jpg, .png",
@@ -270,22 +261,25 @@ defmodule ExDoc.Formatter.HTMLTest do
   end
 
   describe "canonical URL" do
-    test "is included when canonical options is specified" do
+    test "is included when canonical options is specified", %{tmp_dir: tmp_dir} = context do
       config =
-        doc_config(extras: ["test/fixtures/README.md"], canonical: "https://hexdocs.pm/elixir/")
+        doc_config(context,
+          extras: ["test/fixtures/README.md"],
+          canonical: "https://hexdocs.pm/elixir/"
+        )
 
       generate_docs(config)
-      content = File.read!("#{output_dir()}/api-reference.html")
+      content = File.read!(tmp_dir <> "/html/api-reference.html")
       assert content =~ ~r{<link rel="canonical" href="https://hexdocs.pm/elixir/}
 
-      content = File.read!("#{output_dir()}/readme.html")
+      content = File.read!(tmp_dir <> "/html/readme.html")
       assert content =~ ~r{<link rel="canonical" href="https://hexdocs.pm/elixir/}
     end
 
-    test "is not included when canonical is nil" do
-      config = doc_config(canonical: nil)
+    test "is not included when canonical is nil", %{tmp_dir: tmp_dir} = context do
+      config = doc_config(context, canonical: nil)
       generate_docs(config)
-      content = File.read!("#{output_dir()}/api-reference.html")
+      content = File.read!(tmp_dir <> "/html/api-reference.html")
       refute content =~ ~r{<link rel="canonical" href="}
     end
   end
@@ -299,30 +293,30 @@ defmodule ExDoc.Formatter.HTMLTest do
       "test/fixtures/LivebookFile.livemd"
     ]
 
-    test "includes source `.livemd` files" do
-      generate_docs(doc_config(extras: @extras))
+    test "includes source `.livemd` files", %{tmp_dir: tmp_dir} = context do
+      generate_docs(doc_config(context, extras: @extras))
 
-      refute File.exists?("#{output_dir()}/LICENSE")
-      refute File.exists?("#{output_dir()}/license")
-      refute File.exists?("#{output_dir()}/PlainText.txt")
-      refute File.exists?("#{output_dir()}/plaintext.txt")
-      refute File.exists?("#{output_dir()}/PlainTextFiles.md")
-      refute File.exists?("#{output_dir()}/plaintextfiles.md")
-      refute File.exists?("#{output_dir()}/README.md")
-      refute File.exists?("#{output_dir()}/readme.md")
+      refute File.exists?(tmp_dir <> "/html/LICENSE")
+      refute File.exists?(tmp_dir <> "/html/license")
+      refute File.exists?(tmp_dir <> "/html/PlainText.txt")
+      refute File.exists?(tmp_dir <> "/html/plaintext.txt")
+      refute File.exists?(tmp_dir <> "/html/PlainTextFiles.md")
+      refute File.exists?(tmp_dir <> "/html/plaintextfiles.md")
+      refute File.exists?(tmp_dir <> "/html/README.md")
+      refute File.exists?(tmp_dir <> "/html/readme.md")
 
       assert File.read!("test/fixtures/LivebookFile.livemd") ==
-               File.read!("#{output_dir()}/livebookfile.livemd")
+               File.read!(tmp_dir <> "/html/livebookfile.livemd")
     end
 
-    test "alongside other content" do
-      config = doc_config(main: "readme", extras: @extras)
+    test "alongside other content", %{tmp_dir: tmp_dir} = context do
+      config = doc_config(context, main: "readme", extras: @extras)
       generate_docs(config)
 
-      content = File.read!("#{output_dir()}/index.html")
+      content = File.read!(tmp_dir <> "/html/index.html")
       assert content =~ ~r{<meta http-equiv="refresh" content="0; url=readme.html">}
 
-      content = File.read!("#{output_dir()}/readme.html")
+      content = File.read!(tmp_dir <> "/html/readme.html")
       assert content =~ ~r{<title>README [^<]*</title>}
 
       assert content =~
@@ -356,14 +350,14 @@ defmodule ExDoc.Formatter.HTMLTest do
       assert content =~
                ~s{<a href="https://github.com/elixir-lang/elixir/blob/main/test/fixtures/README.md#L1" title="View Source"}
 
-      content = File.read!("#{output_dir()}/plaintextfiles.html")
+      content = File.read!(tmp_dir <> "/html/plaintextfiles.html")
 
       assert content =~ ~r{Plain Text Files</span>.*</h1>}s
 
       assert content =~
                ~R{<p>Read the <a href="license.html">license</a> and the <a href="plaintext.html">plain-text file</a>.}
 
-      plain_text_file = File.read!("#{output_dir()}/plaintext.html")
+      plain_text_file = File.read!(tmp_dir <> "/html/plaintext.html")
 
       assert plain_text_file =~ ~r{PlainText</span>.*</h1>}s
 
@@ -373,14 +367,14 @@ defmodule ExDoc.Formatter.HTMLTest do
       assert plain_text_file =~ ~s{\n## Neither formatted\n}
       assert plain_text_file =~ ~s{\n      `t:term/0`\n}
 
-      license = File.read!("#{output_dir()}/license.html")
+      license = File.read!(tmp_dir <> "/html/license.html")
 
       assert license =~ ~r{LICENSE</span>.*</h1>}s
 
       assert license =~
                ~s{<pre>\nLicensed under the Apache License, Version 2.0 (the &quot;License&quot;)}
 
-      content = File.read!("#{output_dir()}/livebookfile.html")
+      content = File.read!(tmp_dir <> "/html/livebookfile.html")
 
       assert content =~
                ~s{<a href="https://github.com/elixir-lang/elixir/blob/main/test/fixtures/LivebookFile.livemd#L1" title="View Source"}
@@ -392,29 +386,29 @@ defmodule ExDoc.Formatter.HTMLTest do
                ~s{<img src="https://livebook.dev/badge/v1/blue.svg" alt="Run in Livebook" width="150" />}
     end
 
-    test "with absolute and dot-relative paths for extra" do
+    test "with absolute and dot-relative paths for extra", %{tmp_dir: tmp_dir} = context do
       config =
-        doc_config(
+        doc_config(context,
           extras: ["./test/fixtures/README.md", Path.expand("test/fixtures/LivebookFile.livemd")]
         )
 
       generate_docs(config)
 
-      content = File.read!("#{output_dir()}/readme.html")
+      content = File.read!(tmp_dir <> "/html/readme.html")
 
       assert content =~
                ~s{<a href="https://github.com/elixir-lang/elixir/blob/main/test/fixtures/README.md#L1" title="View Source"}
 
-      content = File.read!("#{output_dir()}/livebookfile.html")
+      content = File.read!(tmp_dir <> "/html/livebookfile.html")
 
       assert content =~
                ~s{<a href="https://github.com/elixir-lang/elixir/blob/main/test/fixtures/LivebookFile.livemd#L1" title="View Source"}
     end
 
-    test "without any other content" do
-      generate_docs(doc_config(source_beam: "unknown", extras: @extras))
+    test "without any other content", %{tmp_dir: tmp_dir} = context do
+      generate_docs(doc_config(context, source_beam: "unknown", extras: @extras))
 
-      content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+      content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
       assert content =~ ~s("modules":[])
 
       assert content =~
@@ -424,15 +418,16 @@ defmodule ExDoc.Formatter.HTMLTest do
                ~s({"group":"","headers":[{"anchor":"heading-without-content","id":"Heading without content"},{"anchor":"header-sample","id":"Header sample"},{"anchor":"more-than","id":"more &gt; than"}],"id":"readme","title":"README"})
     end
 
-    test "containing settext headers while discarding links on header" do
+    test "containing settext headers while discarding links on header",
+         %{tmp_dir: tmp_dir} = context do
       generate_docs(
-        doc_config(
+        doc_config(context,
           source_beam: "unknown",
           extras: ["test/fixtures/ExtraPageWithSettextHeader.md"]
         )
       )
 
-      content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+      content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
 
       assert content =~
                ~s("extras":[{"group":"","headers":[],"id":"api-reference","title":"API Reference"},)
@@ -442,9 +437,9 @@ defmodule ExDoc.Formatter.HTMLTest do
                  ~s(id":"extrapagewithsettextheader","title":"Extra Page Title"}])
     end
 
-    test "with custom names" do
+    test "with custom names", %{tmp_dir: tmp_dir} = context do
       generate_docs(
-        doc_config(
+        doc_config(context,
           extras: [
             "test/fixtures/PlainTextFiles.md",
             "test/fixtures/LICENSE": [filename: "linked-license"],
@@ -453,65 +448,73 @@ defmodule ExDoc.Formatter.HTMLTest do
         )
       )
 
-      refute File.regular?("#{output_dir()}/license.html")
-      assert File.regular?("#{output_dir()}/linked-license.html")
+      refute File.regular?(tmp_dir <> "/html/license.html")
+      assert File.regular?(tmp_dir <> "/html/linked-license.html")
 
-      refute File.regular?("#{output_dir()}/plaintext.html")
-      assert File.regular?("#{output_dir()}/plain_text.html")
+      refute File.regular?(tmp_dir <> "/html/plaintext.html")
+      assert File.regular?(tmp_dir <> "/html/plain_text.html")
 
-      content = File.read!("#{output_dir()}/plaintextfiles.html")
+      content = File.read!(tmp_dir <> "/html/plaintextfiles.html")
 
       assert content =~ ~r{Plain Text Files</span>.*</h1>}s
 
       assert content =~
                ~R{<p>Read the <a href="linked-license.html">license</a> and the <a href="plain_text.html">plain-text file</a>.}
 
-      content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+      content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
       assert content =~ ~r{"id":"linked-license","title":"LICENSE"}
     end
 
-    test "with custom title" do
-      generate_docs(doc_config(extras: ["test/fixtures/README.md": [title: "Getting Started"]]))
-      content = File.read!("#{output_dir()}/readme.html")
+    test "with custom title", %{tmp_dir: tmp_dir} = context do
+      generate_docs(
+        doc_config(context, extras: ["test/fixtures/README.md": [title: "Getting Started"]])
+      )
+
+      content = File.read!(tmp_dir <> "/html/readme.html")
       assert content =~ ~r{<title>Getting Started — Elixir v1.0.1</title>}
-      content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+      content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
 
       assert content =~
                ~r{"group":"","headers":\[[^\]]+\],"id":"readme","title":"Getting Started"}
     end
 
-    test "with custom groups" do
+    test "with custom groups", %{tmp_dir: tmp_dir} = context do
       extra_config = [
         extras: ["test/fixtures/README.md"],
         groups_for_extras: [Intro: ~r/fixtures\/READ.?/]
       ]
 
-      generate_docs(doc_config(extra_config))
-      content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+      generate_docs(doc_config(context, extra_config))
+      content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
       assert content =~ ~r{"group":"Intro","headers":\[[^\]]+\],"id":"readme","title":"README"}
     end
 
-    test "with auto-extracted titles" do
-      generate_docs(doc_config(extras: ["test/fixtures/ExtraPage.md"]))
-      content = File.read!("#{output_dir()}/extrapage.html")
+    test "with auto-extracted titles", %{tmp_dir: tmp_dir} = context do
+      generate_docs(doc_config(context, extras: ["test/fixtures/ExtraPage.md"]))
+      content = File.read!(tmp_dir <> "/html/extrapage.html")
       assert content =~ ~r{<title>Extra Page Title — Elixir v1.0.1</title>}
-      content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+      content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
       assert content =~ ~r{"id":"extrapage","title":"Extra Page Title"}
     end
 
-    test "without api-reference" do
+    test "without api-reference", %{tmp_dir: tmp_dir} = context do
       generate_docs(
-        doc_config(api_reference: false, extras: ["test/fixtures/README.md"], main: "readme")
+        doc_config(context,
+          api_reference: false,
+          extras: ["test/fixtures/README.md"],
+          main: "readme"
+        )
       )
 
-      refute File.exists?("#{output_dir()}/api-reference.html")
-      content = read_wildcard!("#{output_dir()}/dist/sidebar_items-*.js")
+      refute File.exists?(tmp_dir <> "/html/api-reference.html")
+      content = read_wildcard!(tmp_dir <> "/html/dist/sidebar_items-*.js")
       refute content =~ ~r{"id":"api-reference","title":"API Reference"}
     end
 
-    test "pages include links to the previous/next page if applicable" do
+    test "pages include links to the previous/next page if applicable",
+         %{tmp_dir: tmp_dir} = context do
       generate_docs(
-        doc_config(
+        doc_config(context,
           extras: [
             "test/fixtures/LICENSE",
             "test/fixtures/README.md"
@@ -521,14 +524,14 @@ defmodule ExDoc.Formatter.HTMLTest do
 
       # We have three extras: API Reference, LICENSE and README
 
-      content_first = File.read!("#{output_dir()}/api-reference.html")
+      content_first = File.read!(tmp_dir <> "/html/api-reference.html")
 
       refute content_first =~ ~r{Previous Page}
 
       assert content_first =~
                ~r{<a href="license.html" class="bottom-actions-button" rel="next">\s*<span class="subheader">\s*Next Page →\s*</span>\s*<span class="title">\s*LICENSE\s*</span>\s*</a>}
 
-      content_middle = File.read!("#{output_dir()}/license.html")
+      content_middle = File.read!(tmp_dir <> "/html/license.html")
 
       assert content_middle =~
                ~r{<a href="api-reference.html" class="bottom-actions-button" rel="prev">\s*<span class="subheader">\s*← Previous Page\s*</span>\s*<span class="title">\s*API Reference\s*</span>\s*</a>}
@@ -536,7 +539,7 @@ defmodule ExDoc.Formatter.HTMLTest do
       assert content_middle =~
                ~r{<a href="readme.html" class="bottom-actions-button" rel="next">\s*<span class="subheader">\s*Next Page →\s*</span>\s*<span class="title">\s*README\s*</span>\s*</a>}
 
-      content_last = File.read!("#{output_dir()}/readme.html")
+      content_last = File.read!(tmp_dir <> "/html/readme.html")
 
       assert content_last =~
                ~r{<a href="license.html" class="bottom-actions-button" rel="prev">\s*<span class="subheader">\s*← Previous Page\s*</span>\s*<span class="title">\s*LICENSE\s*</span>\s*</a>}
@@ -544,32 +547,37 @@ defmodule ExDoc.Formatter.HTMLTest do
       refute content_last =~ ~r{Next Page}
     end
 
-    test "before_closing_*_tags required by the user are placed in the right place" do
+    test "before_closing_*_tags required by the user are placed in the right place",
+         %{
+           tmp_dir: tmp_dir
+         } = context do
       generate_docs(
-        doc_config(
+        doc_config(context,
           before_closing_head_tag: &before_closing_head_tag/1,
           before_closing_body_tag: &before_closing_body_tag/1,
           extras: ["test/fixtures/README.md"]
         )
       )
 
-      content = File.read!("#{output_dir()}/api-reference.html")
+      content = File.read!(tmp_dir <> "/html/api-reference.html")
       assert content =~ ~r[#{@before_closing_head_tag_content_html}\s*</head>]
       assert content =~ ~r[#{@before_closing_body_tag_content_html}\s*</body>]
 
-      content = File.read!("#{output_dir()}/readme.html")
+      content = File.read!(tmp_dir <> "/html/readme.html")
       assert content =~ ~r[#{@before_closing_head_tag_content_html}\s*</head>]
       assert content =~ ~r[#{@before_closing_body_tag_content_html}\s*</body>]
     end
   end
 
   describe ".build" do
-    test "stores generated content" do
-      config = doc_config(extras: ["test/fixtures/README.md"], logo: "test/fixtures/elixir.png")
+    test "stores generated content", %{tmp_dir: tmp_dir} = context do
+      config =
+        doc_config(context, extras: ["test/fixtures/README.md"], logo: "test/fixtures/elixir.png")
+
       generate_docs(config)
-      content = File.read!("#{output_dir()}/.build")
 
       # Verify necessary files in .build
+      content = File.read!(tmp_dir <> "/html/.build")
       assert content =~ ~r(^readme\.html$)m
       assert content =~ ~r(^api-reference\.html$)m
       assert content =~ ~r(^dist/sidebar_items-[\w]{10}\.js$)m
@@ -584,31 +592,35 @@ defmodule ExDoc.Formatter.HTMLTest do
       files =
         content
         |> String.split("\n", trim: true)
-        |> Enum.map(&Path.join(output_dir(), &1))
+        |> Enum.map(&Path.join(tmp_dir <> "/html", &1))
 
       for file <- files do
         assert File.exists?(file)
       end
     end
 
-    test "does not delete files not listed in .build" do
-      keep = "#{output_dir()}/keep"
-      config = doc_config()
+    test "does not delete files not listed in .build", %{tmp_dir: tmp_dir} = context do
+      keep = tmp_dir <> "/html/keep"
+      config = doc_config(context)
       generate_docs(config)
       File.touch!(keep)
       generate_docs(config)
       assert File.exists?(keep)
-      content = File.read!("#{output_dir()}/.build")
+      content = File.read!(tmp_dir <> "/html/.build")
       refute content =~ ~r{keep}
     end
   end
 
-  test "assets required by the user end up in the right place" do
+  test "assets required by the user end up in the right place", %{tmp_dir: tmp_dir} = context do
     File.mkdir_p!("test/tmp/html_assets/hello")
     File.touch!("test/tmp/html_assets/hello/world")
-    generate_docs(doc_config(assets: "test/tmp/html_assets", logo: "test/fixtures/elixir.png"))
-    assert File.regular?("#{output_dir()}/assets/logo.png")
-    assert File.regular?("#{output_dir()}/assets/hello/world")
+
+    generate_docs(
+      doc_config(context, assets: "test/tmp/html_assets", logo: "test/fixtures/elixir.png")
+    )
+
+    assert File.regular?(tmp_dir <> "/html/assets/logo.png")
+    assert File.regular?(tmp_dir <> "/html/assets/hello/world")
   after
     File.rm_rf!("test/tmp/html_assets")
   end