Avoid creating a new empty talk page when removing a template from a non-existent page

lib/wiki_assignment_output.rb

@@ -39,11 +39,13 @@ def build_talk_page_update
     # Do not post templates to disambugation pages
     return nil if includes_disambiguation_template?(initial_page_content)
 
-    # We only want to add assignment tags to non-existant talk pages if the
+    # We only want to add assignment tags to non-existent talk pages if the
     # article page actually exists, and is not a disambiguation page.
-    article_content = WikiApi.new(@wiki).get_page_content(@title)
-    return nil if article_content.blank?
-    return nil if includes_disambiguation_template?(article_content)
+    return nil unless normal_article?
+
+    # We only want to remove assignments if talk page already exists.
+    # This is to avoid creating a new empty talk page.
+    return nil if @assignments.empty? && initial_page_content.empty?
 
     page_content = build_assignment_page_content(assignments_tag, initial_page_content)
     page_content
@@ -52,6 +54,12 @@ def build_talk_page_update
   ###################
   # Helper methods #
   ###################
+  # Normal article means the article page actually exists, and is not a disambiguation page.
+  def normal_article?
+    article_content = WikiApi.new(@wiki).get_page_content(@title)
+    article_content.present? && !includes_disambiguation_template?(article_content)
+  end
+
   def assignments_tag
     return '' if @assignments.empty?
 
@@ -84,7 +92,7 @@ def assignments_tag
   def build_assignment_page_content(new_tag, page_content)
     page_content = page_content.dup.force_encoding('utf-8')
     # Return if tag already exists on page.
-    # However, if the tag is empty, that means to blank the prior tag (if any).z
+    # However, if the tag is empty, that means to blank the prior tag (if any).
     if new_tag.present?
       return nil if page_content.include? new_tag
     end

spec/lib/wiki_assignment_output_spec.rb

@@ -264,13 +264,26 @@
     let(:title) { 'Selfie' }
     let(:talk_title) { 'Talk:Selfie' }
 
-    context 'when the article exists but talk page does not' do
+    context 'when the article exists but talk page does not,' do
       let(:talk_title) { 'Talk:THIS PAGE DOES NOT EXIST' }
 
-      it 'returns content' do
-        VCR.use_cassette 'wiki_edits/talk_page_update' do
-          page_content = wiki_assignment_output.build_talk_page_update
-          expect(page_content).to include('{{dashboard.wikiedu.org assignment | course = ')
+      context 'adding or updating assignments' do
+        it 'returns content' do
+          VCR.use_cassette 'wiki_edits/talk_page_update' do
+            page_content = wiki_assignment_output.build_talk_page_update
+            expect(page_content).to include('{{dashboard.wikiedu.org assignment | course = ')
+          end
+        end
+      end
+
+      context 'trying to remove assignments' do
+        let(:assignments) { [] }
+
+        it 'returns nil' do
+          VCR.use_cassette 'wiki_edits/talk_page_update' do
+            page_content = wiki_assignment_output.build_talk_page_update
+            expect(page_content).to be_nil
+          end
         end
       end
     end