Add draft front_matter and _drafts folder options

Completes elixir-tools#129

Author: evantravers

Diff for: lib/tableau/extensions/post_extension.ex

@@ -21,6 +21,7 @@ defmodule Tableau.PostExtension do
   title: "The elixir-tools Update Vol. 3"
   permalink: "/news/:title"
   date: "~N[2023-09-19 01:00:00]"
+  draft: false
   layout: "ElixirTools.PostLayout"
   converter: "MyConverter"
   ```
@@ -40,6 +41,7 @@ defmodule Tableau.PostExtension do
   - `:future` - boolean - Show posts that have dates later than the current timestamp, or time at which the site is generated.
   - `:permalink` - string - Default output path for posts. Accepts `:title` as a replacement keyword, replaced with the post's provided title. If a post has a `:permalink` provided, that will override this value _for that post_.
   - `:layout` - string - Elixir module providing page layout for posts. Default is nil
+  - `:draft` - boolean - Only show this post in dev.
 
   ### Example
 
@@ -90,6 +92,7 @@ defmodule Tableau.PostExtension do
       map(%{
         optional(:enabled) => bool(),
         optional(:dir, "_posts") => str(),
+        optional(:drafts, "_drafts") => str(),
         optional(:future, false) => bool(),
         optional(:permalink) => str(),
         optional(:layout) => oneof([atom(), str()])
@@ -129,6 +132,14 @@ defmodule Tableau.PostExtension do
           Enum.reject(posts, fn {post, _} -> DateTime.after?(post.date, DateTime.utc_now()) end)
         end
       end)
+      |> then(fn posts ->
+        unless config.drafts do
+          posts
+        else
+          Enum.reject(posts, fn {post, _} -> post.file =~ config.drafts end)
+        end
+      end)
+      |> Enum.reject(fn {post, _} -> Map.get(post, :draft, false) == true end)
 
     graph =
       Tableau.Graph.insert(

Diff for: test/tableau/extensions/post_extension_test.exs

@@ -26,8 +26,8 @@ defmodule Tableau.PostExtensionTest do
   @moduletag :tmp_dir
 
   describe "config" do
-    test "provides defaults for dir and future fields" do
-      assert {:ok, %{dir: "_posts", future: false}} = PostExtension.config(%{})
+    test "provides defaults for dir, drafts, and future fields" do
+      assert {:ok,%{dir: "_posts", drafts: "_drafts", future: false}} = PostExtension.config(%{})
     end
   end
 
@@ -163,6 +163,55 @@ defmodule Tableau.PostExtensionTest do
       assert Blog.PostLayout in vertices
     end
 
+    test "drafts: true will not render a post", %{tmp_dir: dir, token: token} do
+      File.write(Path.join(dir, "my-draft-post.md"), """
+      ---
+      layout: Blog.PostLayout
+      title: My Draft Post
+      date: 2020-01-01
+      categories: post
+      permalink: /post/2020/01/01/my-draft-post/
+      draft: true
+      ---
+
+      Do androids dream of electric sheep?
+      """)
+
+      assert {:ok, config} = PostExtension.config(%{dir: dir, enabled: true})
+
+      token = put_in(token.extensions.posts.config, config)
+
+      assert {:ok, token} = PostExtension.run(token)
+
+      assert %{
+        posts: [],
+      } = token
+    end
+
+    test "files in config.drafts will not render a post", %{tmp_dir: dir, token: token} do
+      File.write(Path.join("_drafts", "my-post-in-drafts-folder.md"), """
+      ---
+      layout: Blog.PostLayout
+      title: My Draft Post in Drafts Folder
+      date: 2020-01-01
+      categories: post
+      permalink: /post/2020/01/02/my-post-in-drafts-folder/
+      ---
+
+      Do androids dream of electric sheep?
+      """)
+
+      assert {:ok, config} = PostExtension.config(%{dir: dir, enabled: true})
+
+      token = put_in(token.extensions.posts.config, config)
+
+      assert {:ok, token} = PostExtension.run(token)
+
+      assert %{
+        posts: [],
+      } = token
+    end
+
     test "configured permalink works when you dont specify one", %{tmp_dir: dir, token: token} do
       File.write(Path.join(dir, "my-future-post.md"), """
       ---