Add Enforce Runtime Attributes rule (lyft#56)

README.md

@@ -40,6 +40,14 @@ in the .xib or .storyboard file.
   Checks for labels with outlets into a view controller that have no accessibility identifiers.
   Labels with outlets might get dynamic text, and therefore should be accessible to UI testing.
 
+- `enforce_runtime_attributes`
+
+  Ensures a runtime attribute is set to one of the allowed values. Configure `runtime_attributes` in a custom rule configuration using `rules_config` (see below). Use `null` as an option to allow no value.
+
+- `enforce_system_properties`
+
+  Ensures a property in a system type is set to one of the allowed values. Configure `system_properties` in a custom rule configuration using `rules_config` (see below). Use `null` as an option to allow default value.
+
 - `named_colors`
 
   Ensures all colors are using named colors from an asset catalog. Configure `ignore_alpha` (default is `false`) in a custom rule configuration using `rules_config` (see below) if you’d like to ignore colors with alpha.
@@ -76,10 +84,6 @@ in the .xib or .storyboard file.
 
   Ensures a system type uses a set of custom clases. Configure `system_classes` in a custom rule configuration using `rules_config` (see below).
 
-- `enforce_system_properties`
-
-  Ensures a property in a system type is set to one of the allowed properties. Configure `system_properties` in a custom rule configuration using `rules_config` (see below). Use `null` as an option to allow default value.
-
 ## Usage
 
 For a list of available rules, run `xiblint -h`.

xiblint/__init__.py

@@ -1 +1 @@
-__version__ = '0.9.13'
+__version__ = '0.9.14'

xiblint/rules/enforce_runtime_attributes.py

@@ -0,0 +1,54 @@
+from xiblint.rules import Rule
+from xiblint.xibcontext import XibContext
+
+
+class EnforceRuntimeAttributes(Rule):
+    """
+    Ensures a runtime attribute is set to one of the allowed values.
+
+    You must specify a module as part of the class name if it is a custom type.
+
+    Example configuration:
+    {
+      "runtime_attributes": {
+        "SomeModule.LegacyButton": {
+          "sizeName": ["small", "large"]
+        },
+        "button": {
+          "layer.cornerRadius": [null]
+        }
+      }
+    }
+    """
+    def check(self, context):  # type: (XibContext) -> None
+        runtime_attributes = self.config.get('runtime_attributes', {})
+
+        for full_class_name in runtime_attributes.keys():
+            enforced_attributes = runtime_attributes.get(full_class_name)
+
+            # Get system or custom class elements
+            full_class_name_split = full_class_name.split(".")
+            if len(full_class_name_split) == 1:
+                elements = context.tree.findall(".//{}".format(full_class_name))
+            elif len(full_class_name_split) == 2:
+                elements = context.tree.findall(".//*[@customClass='{}'][@customModule='{}']"
+                                                .format(full_class_name_split[1], full_class_name_split[0]))
+
+            for element in elements:
+                for attribute_keyPath in enforced_attributes.keys():
+                    attribute_allowed_values = enforced_attributes.get(attribute_keyPath)
+                    attribute_value = None
+
+                    attribute_list = element.find("./userDefinedRuntimeAttributes")
+                    if attribute_list is not None:
+                        attribute_element = attribute_list.find("./userDefinedRuntimeAttribute/[@keyPath='{}']"
+                                                                .format(attribute_keyPath))
+                        if attribute_element is not None:
+                            attribute_value = attribute_element.get("value")
+
+                    if attribute_value in attribute_allowed_values:
+                        continue
+
+                    options_string = '`, `'.join(map(str, attribute_allowed_values))
+                    context.error(element, '`<{}>` runtime attribute `{}` must use `{}` instead of `{}`.'
+                                  .format(full_class_name, attribute_keyPath, options_string, attribute_value))

xiblint/rules/enforce_system_properties.py

@@ -4,7 +4,7 @@
 
 class EnforceSystemProperties(Rule):
     """
-    Ensures unavailable system properties are not used.
+    Ensures a property in a system type is set to one of the allowed values.
 
     Example configuration:
     {