Mutable drops should fallback to their own methods when a mutation isn't present (#6350)

Merge pull request 6350

lib/jekyll/drops/drop.rb

@@ -104,11 +104,9 @@ module Jekyll
       #
       # Returns true if the given key is present
       def key?(key)
-        if self.class.mutable?
-          @mutations.key?(key)
-        else
-          !key.nil? && (respond_to?(key) || fallback_data.key?(key))
-        end
+        return false if key.nil?
+        return true if self.class.mutable? && @mutations.key?(key)
+        respond_to?(key) || fallback_data.key?(key)
       end
 
       # Generates a list of keys with user content as their values.

test/test_drop.rb

@@ -10,12 +10,12 @@ class DropFixture < Jekyll::Drops::Drop
   end
 
   def fallback_data
-    @fallback_data ||= {}
+    @fallback_data ||= { "baz" => "buzz" }
   end
 end
 
 class TestDrop < JekyllUnitTest
-  context "a document drop" do
+  context "Drops" do
     setup do
       @site = fixture_site({
         "collections" => ["methods"],
@@ -52,6 +52,7 @@ class TestDrop < JekyllUnitTest
       end
     end
 
+    context "a document drop" do
       context "fetch" do
         should "raise KeyError if key is not found and no default provided" do
           assert_raises KeyError do
@@ -87,4 +88,32 @@ class TestDrop < JekyllUnitTest
         end
       end
     end
+
+    context "key?" do
+      context "a mutable drop" do
+        should "respond true for native methods" do
+          assert @drop.key? "foo"
+        end
+
+        should "respond true for mutable keys" do
+          @drop["bar"] = "baz"
+          assert @drop.key? "bar"
+        end
+
+        should "return true for fallback data" do
+          assert @drop.key? "baz"
+        end
+      end
+
+      context "a document drop" do
+        should "respond true for native methods" do
+          assert @document_drop.key? "collection"
+        end
+
+        should "return true for fallback data" do
+          assert @document_drop.key? "title"
+        end
+      end
+    end
+  end
 end