Use black to format hassfest generated files (#78794)

script/hassfest/config_flow.py

@@ -1,9 +1,10 @@
 """Generate config flow file."""
 from __future__ import annotations
 
-import json
+import black
 
 from .model import Config, Integration
+from .serializer import to_string
 
 BASE = """
 \"\"\"Automatically generated by hassfest.
@@ -11,8 +12,6 @@ BASE = """
 To update, run python3 -m script.hassfest
 \"\"\"
 
-# fmt: off
-
 FLOWS = {}
 """.strip()
 
@@ -85,7 +84,7 @@ def generate_and_validate(integrations: dict[str, Integration], config: Config):
 
         domains[integration.integration_type].append(domain)
 
-    return BASE.format(json.dumps(domains, indent=4))
+    return black.format_str(BASE.format(to_string(domains)), mode=black.Mode())
 
 
 def validate(integrations: dict[str, Integration], config: Config):
@@ -97,7 +96,7 @@ def validate(integrations: dict[str, Integration], config: Config):
         return
 
     with open(str(config_flow_path)) as fp:
-        if fp.read().strip() != content:
+        if fp.read() != content:
             config.add_error(
                 "config_flow",
                 "File config_flows.py is not up to date. "
@@ -111,4 +110,4 @@ def generate(integrations: dict[str, Integration], config: Config):
     """Generate config flow file."""
     config_flow_path = config.root / "homeassistant/generated/config_flows.py"
     with open(str(config_flow_path), "w") as fp:
-        fp.write(f"{config.cache['config_flow']}\n")
+        fp.write(f"{config.cache['config_flow']}")