data_type: Add StringDict data type.

StringDict is a data type for representing dictionaries where
all keys and values are strings. Add this data type to data_types.py
and edit other files so that this data type is put to use and tested.

(slightly tweaked by @showell to remove a comment and shorten
a var name now that we have a proper data type)

tools/check-node-fixtures

@@ -47,6 +47,7 @@ from zerver.lib.data_types import (
     EnumType,
     ListType,
     NumberType,
+    StringDictType,
     UnionType,
     make_checker,
     schema,
@@ -62,9 +63,6 @@ SKIP_LIST = [
 
 
 EXEMPT_OPENAPI_NAMES = [
-    # bots
-    "realm_bot_add_event",
-    "realm_bot_update_event",
     # users field missing
     "update_display_settings_event",
     "update_global_notifications_event",
@@ -132,6 +130,8 @@ def from_openapi(node: Dict[str, Any]) -> Any:
             # this might be a glitch in our current spec?  or
             # maybe I just understand it yet
             if isinstance(node["additionalProperties"], dict):
+                if node["additionalProperties"].get("type", "") == "string":
+                    return StringDictType()
                 return from_openapi(node["additionalProperties"])
 
         if "properties" not in node:

zerver/lib/data_types.py

@@ -121,6 +121,21 @@ class ListType:
         return f"{var_name} (list):\n{indent(sub_schema)}"
 
 
+@dataclass
+class StringDictType:
+    def check_data(self, var_name: str, val: Dict[Any, Any]) -> None:
+        if not isinstance(val, dict):
+            raise AssertionError(f"{var_name} is not a dictionary")
+
+        for key, value in val.items():
+            if isinstance(key, str) and isinstance(value, str):
+                continue
+            raise AssertionError(f"{var_name} is not a string:string dictionary")
+
+    def schema(self, var_name: str) -> str:
+        return f"{var_name}: string_dict"
+
+
 @dataclass
 class OptionalType:
     sub_type: Any

zerver/lib/event_schema.py

@@ -14,6 +14,7 @@ from zerver.lib.data_types import (
     ListType,
     NumberType,
     OptionalType,
+    StringDictType,
     UnionType,
     UrlType,
     check_data,
@@ -313,16 +314,13 @@ bot_services_outgoing_type = DictType(
     ]
 )
 
-# We use a strict check here, because our tests
-# don't specifically focus on seeing how
-# flexible we can make the types be for config_data.
-_ad_hoc_config_data_schema = Equals(dict(foo="bar"))
+config_data_schema = StringDictType()
 
 bot_services_embedded_type = DictType(
     required_keys=[
         # force vertical
         ("service_name", str),
-        ("config_data", _ad_hoc_config_data_schema),
+        ("config_data", config_data_schema),
     ]
 )
 

zerver/tests/test_data_types.py

@@ -5,6 +5,7 @@ from zerver.lib.data_types import (
     ListType,
     NumberType,
     OptionalType,
+    StringDictType,
     UnionType,
     UrlType,
     schema,
@@ -27,12 +28,14 @@ class MiscTest(ZulipTestCase):
                 ("flag", bool),
                 ("level", EnumType([1, 2, 3])),
                 ("lst", ListType(int)),
+                ("config", StringDictType()),
                 ("value", UnionType([int, str])),
                 ("url", UrlType()),
             ]
         )
         expected = """
 test (dict):
+    config: string_dict
     flag: bool
     level in [1, 2, 3]
     lst (list):