Add revert!/discard and rebuild nodes#edit around the new hierarchy

revert! discards exactly the topmost non-empty layer -- autosave if
present, else draft -- and reveals whatever's beneath it, releasing the
lock only once nothing is left to protect. Guards against destroying a
brand-new, never-published node's only draft, which would violate the
(head | draft) invariant every other method here assumes holds; the
view's Destroy/Discard button is gated the same way.

nodes#edit now calls lock_for_editing! instead of find_or_create_draft,
and always displays autosave || draft || head, resurrecting an
abandoned session's unsaved content by default with an explicit flash
explaining what's shown and how to get back to the last saved version.

The view drops content_for :subnavigation entirely: Show becomes
"Unlock + Back", Preview stays a plain link, metadata's own <details>
already replaced the old toggle, and Publish moves off this page for
good, per the earlier decision to manage the publish lifecycle
entirely from nodes#show. Save Draft and Save + Unlock + Exit appear
both above and below the form, given the body field alone runs 600px
on desktop.

1 files changed, 87 insertions, 0 deletions

diff --git a/test/models/node_test.rb b/test/models/node_test.rb
index bdf556d..2138c19 100644
--- a/test/models/node_test.rb
+++ b/test/models/node_test.rb
@@ -379,6 +379,93 @@ class NodeTest < ActiveSupport::TestCase
     assert_nil node.autosave
     assert_nil node.lock_owner
   end
+
+  test "revert! is a safe no-op on a fresh node with only a draft" do
+    node = create_node_with_draft
+    node.lock_for_editing!(@user1)
+
+    node.revert!(@user1)
+    node.reload
+
+    assert_not_nil node.draft
+    assert_equal @user1, node.lock_owner
+  end
+
+  test "revert! discards an autosave on a fresh node without touching its only draft" do
+    node = create_node_with_draft
+    node.lock_for_editing!(@user1)
+    node.autosave!({ :title => "typing" }, @user1)
+
+    node.revert!(@user1)
+    node.reload
+
+    assert_nil node.autosave
+    assert_not_nil node.draft
+    assert_equal @user1, node.lock_owner
+  end
+
+  test "revert! does nothing when a published node has no draft or autosave" do
+    node = create_node_with_published_page
+    node.lock_for_editing!(@user1)
+
+    node.revert!(@user1)
+    node.reload
+
+    assert_not_nil node.head
+    assert_nil node.draft
+  end
+
+  test "revert! discards a fresh autosave and releases the lock when no draft exists" do
+    node = create_node_with_published_page
+    node.lock_for_editing!(@user1)
+    node.autosave!({ :title => "in progress" }, @user1)
+
+    node.revert!(@user1)
+    node.reload
+
+    assert_nil node.autosave
+    assert_nil node.draft
+    assert_nil node.lock_owner
+  end
+
+  test "revert! destroys an existing draft and releases the lock" do
+    node = create_node_with_published_page
+    head_title = node.head.title
+    node.lock_for_editing!(@user1)
+    node.autosave!({ :title => "second version" }, @user1)
+    node.save_draft!(@user1)
+
+    node.revert!(@user1)
+    node.reload
+
+    assert_nil node.draft
+    assert_equal head_title, node.head.title
+    assert_nil node.lock_owner
+  end
+
+  test "revert! discards only the autosave when a draft survives beneath it" do
+    node = create_node_with_published_page
+    node.lock_for_editing!(@user1)
+    node.autosave!({ :title => "second version" }, @user1)
+    node.save_draft!(@user1)
+    node.autosave!({ :title => "third version, still typing" }, @user1)
+
+    node.revert!(@user1)
+    node.reload
+
+    assert_nil node.autosave
+    assert_not_nil node.draft
+    assert_equal "second version", node.draft.title
+    assert_equal @user1, node.lock_owner
+  end
+
+  test "revert! raises LockedByAnotherUser for a non-owner" do
+    node = create_node_with_published_page
+    node.lock_for_editing!(@user1)
+
+    assert_raise(LockedByAnotherUser) { node.revert!(@user2) }
+    assert_equal @user1, node.reload.lock_owner
+  end
   
   def create_revisions node, count
     count.times do