Zeroconf discovery for config entries (#23919)

* Proof of concept

* Follow comments

* Fix line length and bad imports

* Move imports to top

* Exception handling for unicode decoding
Create debug print for new service types
Add empty test files

* First try at a test

* Add type and name to service info
Fix static check

* Add aiozeroconf to test dependencies

script/hassfest/zeroconf.py

@@ -0,0 +1,63 @@
+"""Generate zeroconf file."""
+import json
+from typing import Dict
+
+from .model import Integration, Config
+
+BASE = """
+\"\"\"Automatically generated by hassfest.
+
+To update, run python3 -m hassfest
+\"\"\"
+
+
+SERVICE_TYPES = {}
+""".strip()
+
+
+def generate_and_validate(integrations: Dict[str, Integration]):
+    """Validate and generate zeroconf data."""
+    service_type_dict = {}
+
+    for domain in sorted(integrations):
+        integration = integrations[domain]
+
+        if not integration.manifest:
+            continue
+
+        service_types = integration.manifest.get('zeroconf')
+
+        if not service_types:
+            continue
+
+        for service_type in service_types:
+
+            if service_type not in service_type_dict:
+                service_type_dict[service_type] = []
+
+            service_type_dict[service_type].append(domain)
+
+    return BASE.format(json.dumps(service_type_dict, indent=4))
+
+
+def validate(integrations: Dict[str, Integration], config: Config):
+    """Validate zeroconf file."""
+    zeroconf_path = config.root / 'homeassistant/generated/zeroconf.py'
+    config.cache['zeroconf'] = content = generate_and_validate(integrations)
+
+    with open(str(zeroconf_path), 'r') as fp:
+        if fp.read().strip() != content:
+            config.add_error(
+                "zeroconf",
+                "File zeroconf.py is not up to date. "
+                "Run python3 -m script.hassfest",
+                fixable=True
+            )
+        return
+
+
+def generate(integrations: Dict[str, Integration], config: Config):
+    """Generate zeroconf file."""
+    zeroconf_path = config.root / 'homeassistant/generated/zeroconf.py'
+    with open(str(zeroconf_path), 'w') as fp:
+        fp.write(config.cache['zeroconf'] + '\n')