Merge pull request #35661 from jhawthorn/lookup_context_validation

Validate types assigned to LookupContext#formats=

3 files changed, 18 insertions, 2 deletions

diff --git a/actionview/lib/action_view/lookup_context.rb b/actionview/lib/action_view/lookup_context.rb
index 2eaf188ecf..fd3d025cbf 100644
--- a/actionview/lib/action_view/lookup_context.rb
+++ b/actionview/lib/action_view/lookup_context.rb
@@ -280,7 +280,15 @@ module ActionView
     # add :html as fallback to :js.
     def formats=(values)
       if values
+        values = values.dup
         values.concat(default_formats) if values.delete "*/*"
+        values.uniq!
+
+        invalid_values = (values - Template::Types.symbols)
+        unless invalid_values.empty?
+          raise ArgumentError, "Invalid formats: #{invalid_values.map(&:inspect).join(", ")}"
+        end
+
         if values == [:js]
           values << :html
           @html_fallback_for_js = true
diff --git a/actionview/lib/action_view/rendering.rb b/actionview/lib/action_view/rendering.rb
index ac861c44d4..5a06bd9da6 100644
--- a/actionview/lib/action_view/rendering.rb
+++ b/actionview/lib/action_view/rendering.rb
@@ -127,7 +127,7 @@ module ActionView
       # Assign the rendered format to look up context.
       def _process_format(format)
         super
-        lookup_context.formats = [format.to_sym]
+        lookup_context.formats = [format.to_sym] if format.to_sym
       end
 
       # Normalize args by converting render "foo" to render :action => "foo" and
diff --git a/actionview/test/template/lookup_context_test.rb b/actionview/test/template/lookup_context_test.rb
index 537f8ee163..3e357fe1a7 100644
--- a/actionview/test/template/lookup_context_test.rb
+++ b/actionview/test/template/lookup_context_test.rb
@@ -67,7 +67,7 @@ class LookupContextTest < ActiveSupport::TestCase
 
   test "handles explicitly defined */* formats fallback to :js" do
     @lookup_context.formats = [:js, Mime::ALL]
-    assert_equal [:js, *Mime::SET.symbols], @lookup_context.formats
+    assert_equal [:js, *Mime::SET.symbols].uniq, @lookup_context.formats
   end
 
   test "adds :html fallback to :js formats" do
@@ -75,6 +75,14 @@ class LookupContextTest < ActiveSupport::TestCase
     assert_equal [:js, :html], @lookup_context.formats
   end
 
+  test "raises on invalid format assignment" do
+    ex = assert_raises ArgumentError do
+      @lookup_context.formats = [:html, :invalid, "also bad"]
+    end
+
+    assert_equal 'Invalid formats: :invalid, "also bad"', ex.message
+  end
+
   test "provides getters and setters for locale" do
     @lookup_context.locale = :pt
     assert_equal :pt, @lookup_context.locale