add revert action

test/test_app.rb

@@ -97,6 +97,43 @@ context "Frontend" do
     assert last_response.ok?
   end
 
+  test "reverts single commit" do
+    page1 = @wiki.page('B')
+
+    post "/revert/B/7c45b5f16ff3bae2a0063191ef832701214d4df5"
+    follow_redirect!
+    assert last_response.ok?
+
+    @wiki.clear_cache
+    page2 = @wiki.page('B')
+    assert_not_equal page1.version.sha, page2.version.sha
+    assert_equal "INITIAL", page2.raw_data.strip
+  end
+
+  test "reverts multiple commits" do
+    page1 = @wiki.page('A')
+
+    post "/revert/A/302a5491a9a5ba12c7652ac831a44961afa312d2/b26b791cb7917c4f37dd9cb4d1e0efb24ac4d26f"
+    follow_redirect!
+    assert last_response.ok?
+
+    @wiki.clear_cache
+    page2 = @wiki.page('A')
+    assert_not_equal page1.version.sha, page2.version.sha
+    assert_equal "INITIAL", page2.raw_data.strip
+  end
+
+  test "cannot revert conflicting commit" do
+    page1 = @wiki.page('A')
+
+    post "/revert/A/302a5491a9a5ba12c7652ac831a44961afa312d2"
+    assert last_response.ok?
+
+    @wiki.clear_cache
+    page2 = @wiki.page('A')
+    assert_equal page1.version.sha, page2.version.sha
+  end
+
   def app
     Precious::App
   end