Add pipeline tests for nx/xx and prevent HashModel nx/xx with pipeline

- HashModel raises ValueError when nx/xx used with pipeline (not atomic)
- JsonModel supports nx/xx with pipeline (JSON.SET is atomic)
- Added test coverage for these behaviors

Author: abrookins

aredis_om/model/model.py

@@ -2639,6 +2639,11 @@ async def save(
     ) -> Optional["Model"]:
         if nx and xx:
             raise ValueError("Cannot specify both nx and xx")
+        if pipeline and (nx or xx):
+            raise ValueError(
+                "Cannot use nx or xx with pipeline for HashModel. "
+                "Use JsonModel if you need conditional saves with pipelines."
+            )
 
         self.check()
         db = self._get_db(pipeline)

tests/test_hash_model.py

@@ -1446,3 +1446,24 @@ async def test_save_nx_xx_mutually_exclusive(m):
 
     with pytest.raises(ValueError, match="Cannot specify both nx and xx"):
         await member.save(nx=True, xx=True)
+
+
+@py_test_mark_asyncio
+async def test_save_nx_with_pipeline_raises_error(m):
+    """Test that save(nx=True) with pipeline raises an error for HashModel."""
+    await Migrator().run()
+
+    member = m.Member(
+        id=4000,
+        first_name="Andrew",
+        last_name="Brookins",
+        email="a@example.com",
+        join_date=today,
+        age=38,
+        bio="Bio 1",
+    )
+
+    # HashModel doesn't support nx/xx with pipeline (HSET doesn't support it natively)
+    async with m.Member.db().pipeline(transaction=True) as pipe:
+        with pytest.raises(ValueError, match="Cannot use nx or xx with pipeline"):
+            await member.save(pipeline=pipe, nx=True)

tests/test_json_model.py

@@ -1658,3 +1658,38 @@ async def test_save_nx_xx_mutually_exclusive(m, address):
 
     with pytest.raises(ValueError, match="Cannot specify both nx and xx"):
         await member.save(nx=True, xx=True)
+
+
+@py_test_mark_asyncio
+async def test_save_nx_with_pipeline(m, address):
+    """Test that save(nx=True) works with pipeline."""
+    await Migrator().run()
+
+    member1 = m.Member(
+        first_name="Andrew",
+        last_name="Brookins",
+        email="a@example.com",
+        join_date=today,
+        age=38,
+        address=address,
+    )
+    member2 = m.Member(
+        first_name="Kim",
+        last_name="Brookins",
+        email="k@example.com",
+        join_date=today,
+        age=34,
+        address=address,
+    )
+
+    # Save both with nx=True via pipeline
+    async with m.Member.db().pipeline(transaction=True) as pipe:
+        await member1.save(pipeline=pipe, nx=True)
+        await member2.save(pipeline=pipe, nx=True)
+        await pipe.execute()
+
+    # Verify both were saved
+    fetched1 = await m.Member.get(member1.pk)
+    fetched2 = await m.Member.get(member2.pk)
+    assert fetched1.first_name == "Andrew"
+    assert fetched2.first_name == "Kim"