asset check factory docs (#17515)

Used sandy's example from
https://www.notion.so/dagster/Proposal-Checks-APIs-and-docs-ffae0224509043dc84df700199f88315

docs/content/concepts/assets/asset-checks.mdx

@@ -158,6 +158,59 @@ defs = Definitions(
 
 There are a variety of types supported via the <PyObject object="MetadataValue" /> class. You can view the metadata on the **Checks** tab of the **Asset details** page.
 
+### Asset check factories
+
+If you want to define many checks that are similar, you can use the factory pattern. Here's an example factory that accepts a list of sql statements and turns them in to asset checks.
+
+```python file=/concepts/assets/asset_checks/factory.py
+from typing import Any, Mapping, Sequence
+
+from dagster import AssetCheckResult, Definitions, asset, asset_check
+
+
+@asset
+def orders():
+    ...
+
+
+@asset
+def items():
+    ...
+
+
+def make_checks(check_blobs: Sequence[Mapping[str, str]]):
+    checks = []
+    for check_blob in check_blobs:
+
+        @asset_check(name=check_blob["name"], asset=check_blob["asset"])
+        def _check(context):
+            db_connection = ...
+            rows = db_connection.execute(check_blob["sql"])
+            return AssetCheckResult(
+                passed=len(rows) == 0, metadata={"num_rows": len(rows)}
+            )
+
+        checks.append(_check)
+
+    return checks
+
+
+check_blobs = [
+    {
+        "name": "orders_id_has_no_nulls",
+        "asset": "orders",
+        "sql": "select * from orders where order_id is null",
+    },
+    {
+        "name": "items_id_has_no_nulls",
+        "asset": "items",
+        "sql": "select * from items where item_id is null",
+    },
+]
+
+defs = Definitions(assets=[orders, items], asset_checks=make_checks(check_blobs))
+```
+
 ---
 
 ## Executing checks

examples/docs_snippets/docs_snippets/concepts/assets/asset_checks/factory.py

@@ -0,0 +1,46 @@
+from typing import Any, Mapping, Sequence
+
+from dagster import AssetCheckResult, Definitions, asset, asset_check
+
+
+@asset
+def orders():
+    ...
+
+
+@asset
+def items():
+    ...
+
+
+def make_checks(check_blobs: Sequence[Mapping[str, str]]):
+    checks = []
+    for check_blob in check_blobs:
+
+        @asset_check(name=check_blob["name"], asset=check_blob["asset"])
+        def _check(context):
+            db_connection = ...
+            rows = db_connection.execute(check_blob["sql"])
+            return AssetCheckResult(
+                passed=len(rows) == 0, metadata={"num_rows": len(rows)}
+            )
+
+        checks.append(_check)
+
+    return checks
+
+
+check_blobs = [
+    {
+        "name": "orders_id_has_no_nulls",
+        "asset": "orders",
+        "sql": "select * from orders where order_id is null",
+    },
+    {
+        "name": "items_id_has_no_nulls",
+        "asset": "items",
+        "sql": "select * from items where item_id is null",
+    },
+]
+
+defs = Definitions(assets=[orders, items], asset_checks=make_checks(check_blobs))

examples/docs_snippets/docs_snippets_tests/concepts_tests/assets_tests/test_asset_checks.py

@@ -1,17 +1,34 @@
 import pytest
 
+from dagster._core.definitions.asset_check_spec import AssetCheckKey
+from dagster._core.definitions.events import AssetKey
 from docs_snippets.concepts.assets.asset_checks.asset_with_check import (
     defs as asset_with_check_defs,
 )
+from docs_snippets.concepts.assets.asset_checks.factory import check_blobs, make_checks
 from docs_snippets.concepts.assets.asset_checks.metadata import defs as metadata_defs
 from docs_snippets.concepts.assets.asset_checks.orders_check import defs as orders_defs
 from docs_snippets.concepts.assets.asset_checks.severity import defs as severity_defs
 
 
 @pytest.mark.parametrize(
-    "defs", [orders_defs, asset_with_check_defs, severity_defs, metadata_defs]
+    "defs",
+    [orders_defs, asset_with_check_defs, severity_defs, metadata_defs],
 )
 def test_execute(defs):
     job_def = defs.get_implicit_global_asset_job_def()
     result = job_def.execute_in_process()
     assert result.success
+
+
+def test_factory():
+    assert [c.spec.key for c in make_checks(check_blobs)] == [
+        AssetCheckKey(
+            AssetKey(["orders"]),
+            "orders_id_has_no_nulls",
+        ),
+        AssetCheckKey(
+            AssetKey(["items"]),
+            "items_id_has_no_nulls",
+        ),
+    ]