Test all code snippets in the documentation

Author: Cito

README.md

@@ -16,7 +16,7 @@ The current version 3.0.0a2 of GraphQL-core is up-to-date
 with GraphQL.js version 14.4.2.
 
 All parts of the API are covered by an extensive test suite
-of currently 1905 unit tests.
+of currently 1915 unit tests.
 
 
 ## Documentation

docs/usage/extension.rst

@@ -29,6 +29,8 @@ We also need to attach a resolver function to the new field::
 
 Now we can query only the last name of a human::
 
+    from graphql import graphql_sync
+
     result = graphql_sync(schema, """
         {
           human(id: "1000") {

docs/usage/introspection.rst

@@ -17,6 +17,8 @@ create a query that omits the descriptions with::
 In practice you would run this query against a remote server, but we can also run it
 against the schema we have just built above::
 
+    from graphql import graphql_sync
+
     introspection_query_result = graphql_sync(schema, query)
 
 The ``data`` attribute of the introspection query result now gives us a dictionary,

docs/usage/methods.rst

@@ -9,7 +9,7 @@ executing a query.
 In our case, we could create a ``Root`` class with three methods as root resolvers, like
 so::
 
-    class Root():
+    class Root:
         """The root resolvers"""
 
         def hero(self, info, episode):
@@ -22,7 +22,7 @@ so::
             return droid_data.get(id)
 
 
-Since we haven't defined synchronous methods only, we will use the
+Since we have defined synchronous methods only, we will use the
 :func:`graphql.graphql_sync` function to execute a query, passing a ``Root()`` object as
 the ``root_value``::
 

docs/usage/parser.rst

@@ -34,6 +34,8 @@ the AST document::
 
 This will give the same result as manually creating the AST document::
 
+    from graphql.language.ast import *
+
     document = DocumentNode(definitions=[
         ObjectTypeDefinitionNode(
             name=NameNode(value='Query'),

docs/usage/queries.rst

@@ -28,7 +28,7 @@ Here is one way to use it::
         """)
         print(result)
 
-    asyncio.get_event_loop().run_until_complete(main())
+    asyncio.get_event_loop().run_until_complete(query_artoo())
 
 In our query, we asked for the droid with the id 2001, which is R2-D2, and its primary
 function, Astromech. When everything has been implemented correctly as shown above, you
@@ -79,9 +79,8 @@ Let's see what happens when we make a mistake in the query, by querying a non-ex
 You will get the following result as output::
 
     ExecutionResult(data=None, errors=[GraphQLError(
-        "Cannot query field 'homeTown' on type 'Human'."
-        " Did you mean 'homePlanet'?",
-        locations=[SourceLocation(line=5, column=7)])])
+        "Cannot query field 'homeTown' on type 'Human'. Did you mean 'homePlanet'?",
+        locations=[SourceLocation(line=5, column=9)])])
 
 This is very helpful. Not only do we get the exact location of the mistake in the query,
 but also a suggestion for correcting the bad field name.

docs/usage/resolvers.rst

@@ -41,7 +41,7 @@ them later)::
         '2000': threepio, '2001': artoo}
 
 
-    def get_character_type(character, info):
+    def get_character_type(character, _info, _type):
             return 'Droid' if character['id'] in droid_data else 'Human'
 
 
@@ -50,29 +50,29 @@ them later)::
         return human_data.get(id) or droid_data.get(id)
 
 
-    def get_friends(character, info):
+    def get_friends(character, _info):
         """Allows us to query for a character's friends."""
         return map(get_character, character.friends)
 
 
-    def get_hero(root, info, episode):
+    def get_hero(root, _info, episode):
         """Allows us to fetch the undisputed hero of the trilogy, R2-D2."""
         if episode == 5:
             return luke  # Luke is the hero of Episode V
         return artoo  # Artoo is the hero otherwise
 
 
-    def get_human(root, info, id):
+    def get_human(root, _info, id):
         """Allows us to query for the human with the given id."""
         return human_data.get(id)
 
 
-    def get_droid(root, info, id):
+    def get_droid(root, _info, id):
         """Allows us to query for the droid with the given id."""
         return droid_data.get(id)
 
 
-    def get_secret_backstory(character, info):
+    def get_secret_backstory(_character, _info):
         """Raise an error when attempting to get the secret backstory."""
         raise RuntimeError('secretBackstory is secret.')
 

docs/usage/sdl.rst

@@ -65,6 +65,8 @@ So we would also need to manually define these values, like so::
 This would allow us to query the schema built from SDL just like the manually assembled
 schema::
 
+    from graphql import graphql_sync
+
     result = graphql_sync(schema, """
         {
           hero(episode: EMPIRE) {

docs/usage/validator.rst

@@ -24,15 +24,15 @@ As a result, you will get a complete list of all errors that the validators has
 In this case, we will get::
 
     [GraphQLError(
-        "Expected type String!, found NEWHOPE.",
+        'Expected type String!, found NEWHOPE.',
         locations=[SourceLocation(line=3, column=17)]),
      GraphQLError(
         "Cannot query field 'homeTown' on type 'Human'."
          " Did you mean 'homePlanet'?",
          locations=[SourceLocation(line=5, column=9)]),
      GraphQLError(
-        "Field 'friends' of type '[Character]' must have a"
-         " sub selection of subfields. Did you mean 'friends { ... }'?",
+        "Field 'friends' of type '[Character]' must have a sub selection of subfields."
+         "  Did you mean 'friends { ... }'?",
          locations=[SourceLocation(line=6, column=9)])]
 
 These rules are available in the :data:`specified_rules` list and implemented in the