add test for select_related with limit

tests/test_select_related_with_limit.py

@@ -0,0 +1,107 @@
+from typing import List, Optional
+
+import databases
+import sqlalchemy
+from sqlalchemy import create_engine
+
+import ormar
+import pytest
+
+from tests.settings import DATABASE_URL
+
+db = databases.Database(DATABASE_URL, force_rollback=True)
+metadata = sqlalchemy.MetaData()
+
+
+class Keyword(ormar.Model):
+    class Meta:
+        metadata = metadata
+        database = db
+        tablename = "keywords"
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=50)
+
+
+class KeywordPrimaryModel(ormar.Model):
+    class Meta:
+        metadata = metadata
+        database = db
+        tablename = "primary_models_keywords"
+
+    id: int = ormar.Integer(primary_key=True)
+
+
+class PrimaryModel(ormar.Model):
+    class Meta:
+        metadata = metadata
+        database = db
+        tablename = "primary_models"
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=255, index=True)
+    some_text: str = ormar.Text()
+    some_other_text: Optional[str] = ormar.Text(nullable=True)
+    keywords: Optional[List[Keyword]] = ormar.ManyToMany(
+        Keyword, through=KeywordPrimaryModel
+    )
+
+
+class SecondaryModel(ormar.Model):
+    class Meta:
+        metadata = metadata
+        database = db
+        tablename = "secondary_models"
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+    primary_model: PrimaryModel = ormar.ForeignKey(
+        PrimaryModel,
+        related_name="secondary_models",
+    )
+
+
+@pytest.mark.asyncio
+async def test_create_primary_models():
+    async with db:
+        for name, some_text, some_other_text in [
+            ("Primary 1", "Some text 1", "Some other text 1"),
+            ("Primary 2", "Some text 2", "Some other text 2"),
+            ("Primary 3", "Some text 3", "Some other text 3"),
+            ("Primary 4", "Some text 4", "Some other text 4"),
+            ("Primary 5", "Some text 5", "Some other text 5"),
+            ("Primary 6", "Some text 6", "Some other text 6"),
+            ("Primary 7", "Some text 7", "Some other text 7"),
+            ("Primary 8", "Some text 8", "Some other text 8"),
+            ("Primary 9", "Some text 9", "Some other text 9"),
+            ("Primary 10", "Some text 10", "Some other text 10")]:
+            await PrimaryModel(
+                name=name, some_text=some_text, some_other_text=some_other_text
+            ).save()
+
+        for tag_id in [1, 2, 3, 4, 5]:
+            await Keyword.objects.create(name=f"Tag {tag_id}")
+
+        p1 = await PrimaryModel.objects.get(pk=1)
+        p2 = await PrimaryModel.objects.get(pk=2)
+        for i in range(1, 6):
+            keyword = await Keyword.objects.get(pk=i)
+            if i % 2 == 0:
+                await p1.keywords.add(keyword)
+            else:
+                await p2.keywords.add(keyword)
+        models = await PrimaryModel.objects.prefetch_related("keywords").limit(5).all()
+
+        # This test fails, because of the keywords relation.
+        assert len(models) == 5
+        assert len(models[0].keywords) == 2
+        assert len(models[1].keywords) == 3
+        assert len(models[2].keywords) == 0
+
+
+@pytest.fixture(autouse=True, scope="module")
+def create_test_database():
+    engine = create_engine(DATABASE_URL)
+    metadata.create_all(engine)
+    yield
+    metadata.drop_all(engine)