Add tests for post similarity

website/blog/models.py

@@ -97,8 +97,8 @@ class BlogPostPage(BaseContentPage):
 
         similar_posts = similar_posts.annotate(
             similarity=(models.F("tag_similarity") * 2)
-            * (models.F("title_similarity") * 10)
-            * (models.F("subtitle_similarity"))
+            + (models.F("title_similarity") * 10)
+            + (models.F("subtitle_similarity"))
         ).order_by("-similarity")[:3]
 
         return similar_posts

website/blog/tests.py

@@ -21,6 +21,45 @@ class BlogPostPageTestCase(TestCase):
             self.client.get(self.page.url)
 
 
+class BlogPostPageSimilarityTestCase(TestCase):
+    @classmethod
+    def setUpTestData(cls) -> None:
+        cls.home_page = HomePage.objects.get()
+        cls.blog_post_list_page = BlogPostListPageFactory(parent=cls.home_page)
+        cls.page = BlogPostPageFactory(
+            parent=cls.blog_post_list_page, title="Blog post 1"
+        )
+
+        cls.similar_page_1 = BlogPostPageFactory(
+            parent=cls.blog_post_list_page, title="Blog post 2"
+        )
+        cls.similar_page_2 = BlogPostPageFactory(
+            parent=cls.blog_post_list_page, title="Blog post 3"
+        )
+        cls.similar_page_3 = BlogPostPageFactory(
+            parent=cls.blog_post_list_page, title="Blog post 4"
+        )
+
+        BlogPostPageFactory(parent=cls.blog_post_list_page, title="Legal documents")
+
+    def test_similar_pages(self) -> None:
+        self.assertEqual(
+            set(self.page.get_similar_posts()),
+            {self.similar_page_1, self.similar_page_2, self.similar_page_3},
+        )
+
+    def test_page_similarity(self) -> None:
+        for page in self.page.get_similar_posts():
+            self.assertNotEqual(page.similarity, 0.0)
+
+    def test_ordered_by_similarity(self) -> None:
+        similar_pages = self.page.get_similar_posts()
+        self.assertEqual(
+            list(similar_pages),
+            sorted(similar_pages, key=lambda p: p.similarity, reverse=True),
+        )
+
+
 class BlogPostListPageTestCase(TestCase):
     @classmethod
     def setUpTestData(cls) -> None: