Validate component usage (#23037)

* Update manifest validator

* Update circle

* Update text

* Typo

* fix link to codeowners

* Merge CODEOWNERS into hassfest

* Annotate errors with fixable

* Convert error to warning

* Lint

* Make abs path

* Python 3.5...

* Typo

* Fix tests

script/hassfest/dependencies.py

@@ -0,0 +1,65 @@
+"""Validate dependencies."""
+import pathlib
+import re
+from typing import Set, Dict
+
+from .model import Integration
+
+
+def grep_dir(path: pathlib.Path, glob_pattern: str, search_pattern: str) \
+        -> Set[str]:
+    """Recursively go through a dir and it's children and find the regex."""
+    pattern = re.compile(search_pattern)
+    found = set()
+
+    for fil in path.glob(glob_pattern):
+        if not fil.is_file():
+            continue
+
+        for match in pattern.finditer(fil.read_text()):
+            found.add(match.groups()[0])
+
+    return found
+
+
+# These components will always be set up
+ALLOWED_USED_COMPONENTS = {
+    'persistent_notification',
+}
+
+
+def validate_dependencies(integration: Integration):
+    """Validate all dependencies."""
+    # Find usage of hass.components
+    referenced = grep_dir(integration.path, "**/*.py",
+                          r"hass\.components\.(\w+)")
+    referenced -= ALLOWED_USED_COMPONENTS
+    referenced -= set(integration.manifest['dependencies'])
+
+    if referenced:
+        for domain in sorted(referenced):
+            print("Warning: {} references integration {} but it's not a "
+                  "dependency".format(integration.domain, domain))
+            # Not enforced yet.
+            # integration.add_error(
+            #     'dependencies',
+            #     "Using component {} but it's not a dependency".format(domain)
+            # )
+
+
+def validate(integrations: Dict[str, Integration], config):
+    """Handle dependencies for integrations."""
+    # check for non-existing dependencies
+    for integration in integrations.values():
+        if not integration.manifest:
+            continue
+
+        validate_dependencies(integration)
+
+        # check that all referenced dependencies exist
+        for dep in integration.manifest['dependencies']:
+            if dep not in integrations:
+                integration.add_error(
+                    'dependencies',
+                    "Dependency {} does not exist"
+                )