Merge pull request #3377 from StasDeep/feature/issue-3364

Add handling of errors in contract methods

scrapy/contracts/__init__.py

@@ -42,7 +42,11 @@ class ContractsManager(object):
         requests = []
         for method in self.tested_methods_from_spidercls(type(spider)):
             bound_method = spider.__getattribute__(method)
-            requests.append(self.from_method(bound_method, results))
+            try:
+                requests.append(self.from_method(bound_method, results))
+            except Exception:
+                case = _create_testcase(bound_method, 'contract')
+                results.addError(case, sys.exc_info())
 
         return requests
 

tests/test_contracts.py

@@ -25,6 +25,21 @@ class ResponseMock(object):
     url = 'http://scrapy.org'
 
 
+class CustomSuccessContract(Contract):
+    name = 'custom_success_contract'
+
+    def adjust_request_args(self, args):
+        args['url'] = 'http://scrapy.org'
+        return args
+
+
+class CustomFailContract(Contract):
+    name = 'custom_fail_contract'
+
+    def adjust_request_args(self, args):
+        raise TypeError('Error in adjust_request_args')
+
+
 class CustomFormContract(Contract):
     name = 'custom_form'
     request_cls = FormRequest
@@ -118,12 +133,39 @@ class TestSpider(Spider):
         pass
 
 
+class CustomContractSuccessSpider(Spider):
+    name = 'custom_contract_success_spider'
+
+    def parse(self, response):
+        """
+        @custom_success_contract
+        """
+        pass
+
+
+class CustomContractFailSpider(Spider):
+    name = 'custom_contract_fail_spider'
+
+    def parse(self, response):
+        """
+        @custom_fail_contract
+        """
+        pass
+
+
 class InheritsTestSpider(TestSpider):
     name = 'inherits_demo_spider'
 
 
 class ContractsManagerTest(unittest.TestCase):
-    contracts = [UrlContract, ReturnsContract, ScrapesContract, CustomFormContract]
+    contracts = [
+        UrlContract,
+        ReturnsContract,
+        ScrapesContract,
+        CustomFormContract,
+        CustomSuccessContract,
+        CustomFailContract,
+    ]
 
     def setUp(self):
         self.conman = ContractsManager(self.contracts)
@@ -137,6 +179,9 @@ class ContractsManagerTest(unittest.TestCase):
         self.assertTrue(self.results.failures)
         self.assertFalse(self.results.errors)
 
+    def should_error(self):
+        self.assertTrue(self.results.errors)
+
     def test_contracts(self):
         spider = TestSpider()
 
@@ -209,6 +254,13 @@ class ContractsManagerTest(unittest.TestCase):
         request.callback(response)
         self.should_fail()
 
+    def test_custom_contracts(self):
+        self.conman.from_spider(CustomContractSuccessSpider(), self.results)
+        self.should_succeed()
+
+        self.conman.from_spider(CustomContractFailSpider(), self.results)
+        self.should_error()
+
     def test_errback(self):
         spider = TestSpider()
         response = ResponseMock()