Use less generic exceptions (#95)

Author: leszekhanusz

gql/client.py

@@ -71,10 +71,10 @@ def __init__(
                 session.fetch_schema()
 
     def validate(self, document):
-        if not self.schema:
-            raise Exception(
-                "Cannot validate the document locally, you need to pass a schema."
-            )
+        assert (
+            self.schema
+        ), "Cannot validate the document locally, you need to pass a schema."
+
         validation_errors = validate(self.schema, document)
         if validation_errors:
             raise validation_errors[0]

gql/dsl.py

@@ -124,7 +124,7 @@ def selection_field(field):
     if isinstance(field, DSLField):
         return field
 
-    raise Exception(f'Received incompatible query field: "{field}".')
+    raise TypeError(f'Received incompatible query field: "{field}".')
 
 
 def query(*fields, **kwargs):

gql/gql.py

@@ -1,8 +1,6 @@
-from graphql import Source, parse
+from graphql import DocumentNode, Source, parse
 
 
-def gql(request_string):
-    if not isinstance(request_string, str):
-        raise Exception(f'Received incompatible request "{request_string}".')
+def gql(request_string: str) -> DocumentNode:
     source = Source(request_string, "GraphQL request")
     return parse(source)

scripts/gql-cli

@@ -27,7 +27,7 @@ async def main():
     elif scheme in ["http", "https"]:
         transport = AIOHTTPTransport(url=args.server)
     else:
-        raise Exception("URL protocol should be one of: http, https, ws, wss")
+        raise ValueError("URL protocol should be one of: http, https, ws, wss")
 
     async with Client(transport=transport) as session:
 

tests/starwars/test_validation.py

@@ -75,9 +75,9 @@ def validation_errors(client, query):
 
 
 def test_incompatible_request_gql(client):
-    with pytest.raises(Exception) as exc_info:
+    with pytest.raises(TypeError) as exc_info:
         gql(123)
-    assert "Received incompatible request" in str(exc_info.value)
+    assert "body must be a string" in str(exc_info.value)
 
 
 def test_nested_query_with_fragment(client):

tests/test_client.py

@@ -70,7 +70,7 @@ def test_retries_on_transport(execute_mock):
 
 
 def test_no_schema_exception():
-    with pytest.raises(Exception) as exc_info:
+    with pytest.raises(AssertionError) as exc_info:
         client = Client()
         client.validate("")
     assert "Cannot validate the document locally, you need to pass a schema." in str(