Add test for exporting graphql file

graphene_django/tests/test_command.py

@@ -1,17 +1,21 @@
+from textwrap import dedent
+
 from django.core import management
-from mock import patch, mock_open
+from mock import mock_open, patch
 from six import StringIO
 
+from graphene import ObjectType, Schema, String
+
 
 @patch("graphene_django.management.commands.graphql_schema.Command.save_json_file")
-def test_generate_file_on_call_graphql_schema(savefile_mock, settings):
+def test_generate_json_file_on_call_graphql_schema(savefile_mock, settings):
     out = StringIO()
     management.call_command("graphql_schema", schema="", stdout=out)
     assert "Successfully dumped GraphQL schema to schema.json" in out.getvalue()
 
 
 @patch("json.dump")
-def test_files_are_canonical(dump_mock):
+def test_json_files_are_canonical(dump_mock):
     open_mock = mock_open()
     with patch("graphene_django.management.commands.graphql_schema.open", open_mock):
         management.call_command("graphql_schema", schema="")
@@ -25,3 +29,34 @@ def test_files_are_canonical(dump_mock):
     assert (
         dump_mock.call_args[1]["indent"] > 0
     ), "output should be pretty-printed by default"
+
+
+def test_generate_graphql_file_on_call_graphql_schema():
+    class Query(ObjectType):
+        hi = String()
+
+    mock_schema = Schema(query=Query)
+
+    open_mock = mock_open()
+    with patch("graphene_django.management.commands.graphql_schema.open", open_mock):
+        management.call_command(
+            "graphql_schema", schema=mock_schema, out="schema.graphql"
+        )
+
+    open_mock.assert_called_once()
+
+    handle = open_mock()
+    assert handle.write.called_once()
+
+    schema_output = handle.write.call_args[0][0]
+    assert schema_output == dedent(
+        """\
+        schema {
+          query: Query
+        }
+
+        type Query {
+          hi: String
+        }
+    """
+    )