[resources] readability in start_requests POST handler

+ test for missing "request" argument to POST endpoint

Author: pawelmhm

scrapyrt/resources.py

@@ -145,15 +145,19 @@ def render_POST(self, request, **kwargs):
             raise Error('400', message=message)
 
         log.msg("{}".format(api_params))
+        if api_params.get("start_requests"):
+            # start requests passed so 'request' argument is optional
+            _request = api_params.get("request", {})
+        else:
+            # no start_requests, 'request' is required
+            _request = self.get_required_argument(api_params, "request")
         try:
             scrapy_request_args = extract_scrapy_request_args(
-                api_params.get("request", {}), raise_error=True
+                _request, raise_error=True
             )
         except ValueError as e:
             raise Error(400, e.message)
 
-        if not api_params.get("start_requests"):
-            self.get_required_argument(api_params, "request")
         self.validate_options(scrapy_request_args, api_params)
         return self.prepare_crawl(api_params, scrapy_request_args, **kwargs)
 

tests/test_resource_crawl.py

@@ -126,6 +126,25 @@ def test_no_url_but_start_requests_present(self, server, method):
         assert len(spider_errors) == 0
         assert result["stats"].get("downloader/request_count") == 2
 
+    def test_no_request_but_start_requests_present(self, server):
+        """Test for POST handler checking if everything works fine
+        if there is no 'request' argument, but 'start_requests' are
+        present. Not checked above because of the way default test fixtures
+        are written.
+        """
+        post_data = {
+            "no_request": {},
+            "start_requests": True,
+            "spider_name": "test_with_sr"
+        }
+        post_data.update(post_data)
+        res = requests.post(server.url("crawl.json"),
+                            json=post_data)
+        assert res.status_code == 200
+        data = res.json()
+        assert len(data["items"]) == 2
+        assert data.get("errors") is None
+
     @pytest.mark.parametrize("method", [
         perform_get, perform_post
     ])