feat(client): add is_registered() method (#801)

## Change Summary

Asked for here:
https://discord.com/channels/933860922039099444/933860923117043718/1135458731006632027

## Checklist

- [ ] Unit tests for the changes exist
- [ ] Tests pass without significant drop in coverage
- [ ] Documentation reflects changes where applicable
- [ ] Test snapshots have been
[updated](https://prisma-client-py.readthedocs.io/en/latest/contributing/contributing/#snapshot-tests)
if applicable

## Agreement

By submitting this pull request, I confirm that you can use, modify,
copy and redistribute this contribution, under the terms of your choice.

src/prisma/generator/templates/client.py.jinja

@@ -208,6 +208,13 @@ class Prisma:
             self.disconnect()
     {% endif %}
 
+    def is_registered(self) -> bool:
+        """Returns True if this client instance is registered"""
+        try:
+            return get_client() is self
+        except errors.ClientNotRegisteredError:
+            return False
+
     def is_connected(self) -> bool:
         """Returns True if the client is connected to the query engine, False otherwise."""
         return self.__engine is not None

tests/test_client.py

@@ -243,3 +243,17 @@ async def test_copied_client_does_not_close_engine(client: Prisma) -> None:
 
     assert client.is_connected()
     await client.user.count()  # ensure queries can still be executed
+
+
+def test_is_registered(client: Prisma) -> None:
+    """The Prisma.is_registered() method can be used both when the client is registered
+    and when there is no client registered at all.
+    """
+    assert client.is_registered()
+
+    other_client = Prisma()
+    assert not other_client.is_registered()
+
+    with reset_client():
+        assert not client.is_registered()
+        assert not other_client.is_registered()

tests/test_generation/exhaustive/__snapshots__/test_exhaustive/test_async[client.py].raw

@@ -258,6 +258,13 @@ class Prisma:
         if self.is_connected():
             await self.disconnect()
 
+    def is_registered(self) -> bool:
+        """Returns True if this client instance is registered"""
+        try:
+            return get_client() is self
+        except errors.ClientNotRegisteredError:
+            return False
+
     def is_connected(self) -> bool:
         """Returns True if the client is connected to the query engine, False otherwise."""
         return self.__engine is not None

tests/test_generation/exhaustive/__snapshots__/test_exhaustive/test_sync[client.py].raw

@@ -258,6 +258,13 @@ class Prisma:
         if self.is_connected():
             self.disconnect()
 
+    def is_registered(self) -> bool:
+        """Returns True if this client instance is registered"""
+        try:
+            return get_client() is self
+        except errors.ClientNotRegisteredError:
+            return False
+
     def is_connected(self) -> bool:
         """Returns True if the client is connected to the query engine, False otherwise."""
         return self.__engine is not None