From fb7d4cbce379c4e3fac2ca89b6e0772d0c690935 Mon Sep 17 00:00:00 2001
From: Stas Glubokiy <glubokiy.stas@gmail.com>
Date: Sat, 11 Aug 2018 16:08:26 +0300
Subject: [PATCH 1/3] Add error handling in contracts

---
 scrapy/contracts/__init__.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scrapy/contracts/__init__.py b/scrapy/contracts/__init__.py
index 5eaee3d11..18014e290 100644
--- a/scrapy/contracts/__init__.py
+++ b/scrapy/contracts/__init__.py
@@ -41,7 +41,11 @@ 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:
+                case = _create_testcase(bound_method, 'contract')
+                results.addError(case, sys.exc_info())
 
         return requests
 

From ebbde57eca310d3c5c0f530a2e668572dde4d952 Mon Sep 17 00:00:00 2001
From: Stas Glubokiy <glubokiy.stas@gmail.com>
Date: Sat, 11 Aug 2018 17:50:56 +0300
Subject: [PATCH 2/3] Add custom contracts tests

---
 tests/test_contracts.py | 55 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/tests/test_contracts.py b/tests/test_contracts.py
index 1cea2afb7..078ef6e0d 100644
--- a/tests/test_contracts.py
+++ b/tests/test_contracts.py
@@ -5,7 +5,7 @@ from twisted.trial import unittest
 from scrapy.spiders import Spider
 from scrapy.http import Request
 from scrapy.item import Item, Field
-from scrapy.contracts import ContractsManager
+from scrapy.contracts import ContractsManager, Contract
 from scrapy.contracts.default import (
     UrlContract,
     ReturnsContract,
@@ -22,6 +22,21 @@ 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 TestSpider(Spider):
     name = 'demo_spider'
 
@@ -99,8 +114,34 @@ 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 ContractsManagerTest(unittest.TestCase):
-    contracts = [UrlContract, ReturnsContract, ScrapesContract]
+    contracts = [
+        UrlContract,
+        ReturnsContract,
+        ScrapesContract,
+        CustomSuccessContract,
+        CustomFailContract
+    ]
 
     def setUp(self):
         self.conman = ContractsManager(self.contracts)
@@ -114,6 +155,9 @@ 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()
 
@@ -185,3 +229,10 @@ class ContractsManagerTest(unittest.TestCase):
                 self.results)
         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()

From e2de0a7203b99d8fc71e62539fdd75dad439982a Mon Sep 17 00:00:00 2001
From: Stas Glubokiy <glubokiy.stas@gmail.com>
Date: Sat, 18 Aug 2018 15:24:30 +0300
Subject: [PATCH 3/3] Use except Exception

---
 scrapy/contracts/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scrapy/contracts/__init__.py b/scrapy/contracts/__init__.py
index c62df5ab0..18c59ff22 100644
--- a/scrapy/contracts/__init__.py
+++ b/scrapy/contracts/__init__.py
@@ -44,7 +44,7 @@ class ContractsManager(object):
             bound_method = spider.__getattribute__(method)
             try:
                 requests.append(self.from_method(bound_method, results))
-            except:
+            except Exception:
                 case = _create_testcase(bound_method, 'contract')
                 results.addError(case, sys.exc_info())