Add some models tests

articles/models.py

@@ -110,11 +110,13 @@ class Article(AdminUrlMixin, models.Model):
             self.published_at = timezone.now()
         self.status = self.PUBLISHED
         self.save()
+        return self
 
     def unpublish(self):
         self.published_at = None
         self.status = self.DRAFT
         self.save()
+        return self
 
     def save(self, *args, **kwargs):
         if not self.slug:

articles/tests/test_models.py

@@ -0,0 +1,41 @@
+import pytest
+
+from articles.models import Article, User
+
+
+@pytest.mark.django_db
+def test_publish_article(unpublished_article: Article):
+    assert unpublished_article.status == Article.DRAFT
+    assert unpublished_article.published_at is None
+    published_article = unpublished_article.publish()
+    assert published_article.status == Article.PUBLISHED
+    assert published_article.published_at is not None
+
+
+@pytest.mark.django_db
+def test_unpublish_article(published_article: Article):
+    assert published_article.status == Article.PUBLISHED
+    assert published_article.published_at is not None
+    unpublished_article = published_article.unpublish()
+    assert unpublished_article.status == Article.DRAFT
+    assert unpublished_article.published_at is None
+
+
+@pytest.mark.django_db
+def test_save_article_adds_missing_slug(author: User):
+    # Explicitly calling bulk_create with one article because it doesn't call save().
+    articles = Article.objects.bulk_create(
+        [Article(author=author, title="noice title", slug="", status=Article.DRAFT)]
+    )
+    article = articles[0]
+    assert article.slug == ""
+    article.save()
+    assert article.slug != ""
+
+
+@pytest.mark.django_db
+def test_save_article_doesnt_change_existing_slug(published_article: Article):
+    original_slug = published_article.slug
+    published_article.title = "This is a brand new title"
+    published_article.save()
+    assert published_article.slug == original_slug