From f087c1ee7415200428fd0cbe9b12b550da6e6172 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <tgoodlet@gmail.com>
Date: Wed, 30 Aug 2017 14:43:31 -0400
Subject: [PATCH 1/4] Add a test which verifies firstresult wrappers

This is to expose the regression from issue #71.
Wrappers must return a single value not a list.
---
 testing/test_hookrelay.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/testing/test_hookrelay.py b/testing/test_hookrelay.py
index 3653151b..46ffadae 100644
--- a/testing/test_hookrelay.py
+++ b/testing/test_hookrelay.py
@@ -87,9 +87,17 @@ class Plugin3(object):
         def hello(self, arg):
             return None
 
+    class Plugin4(object):
+        @hookimpl(hookwrapper=True)
+        def hello(self, arg):
+            assert arg == 3
+            outcome = yield
+            assert outcome.get_result() == 2
+
     pm.register(Plugin1())  # discarded - not the last registered plugin
     pm.register(Plugin2())  # used as result
     pm.register(Plugin3())  # None result is ignored
+    pm.register(Plugin4())  # hookwrapper should get same non-list result
     res = pm.hook.hello(arg=3)
     assert res == 2
 

From dc1d67d00c02cb7848a967a88a1d8260c4c88f15 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <tgoodlet@gmail.com>
Date: Wed, 30 Aug 2017 14:48:39 -0400
Subject: [PATCH 2/4] Always force a single value for firstresult hooks

Ensures that wrappers receive a single value instead of a list.

Fixes #71
---
 pluggy/callers.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pluggy/callers.py b/pluggy/callers.py
index c5934b96..9b9d305f 100644
--- a/pluggy/callers.py
+++ b/pluggy/callers.py
@@ -97,6 +97,10 @@ def execute(self):
                 excinfo = sys.exc_info()
         finally:
             outcome = _Result(results, excinfo)
+            if firstresult:  # first result hooks return a single value
+                results = outcome.get_result()
+                result = results[0] if results else None
+                outcome.force_result(result)
 
             # run all wrapper post-yield blocks
             for gen in reversed(teardowns):
@@ -106,10 +110,6 @@ def execute(self):
                 except StopIteration:
                     pass
 
-            if firstresult:
-                result = outcome.get_result()
-                return result[0] if result else None
-
             return outcome.get_result()
 
     def __repr__(self):

From 9c7246ffd8e9f366af9b30fa114a77e64a81bf11 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <tgoodlet@gmail.com>
Date: Wed, 30 Aug 2017 16:17:49 -0400
Subject: [PATCH 3/4] Simplify outcome generation

Avoids forcing a result with `firstresult` hooks.
Thanks to @RonnyPfannschmidt for the nice simplification.
---
 pluggy/callers.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/pluggy/callers.py b/pluggy/callers.py
index 9b9d305f..642bbcc2 100644
--- a/pluggy/callers.py
+++ b/pluggy/callers.py
@@ -96,11 +96,10 @@ def execute(self):
             except BaseException:
                 excinfo = sys.exc_info()
         finally:
-            outcome = _Result(results, excinfo)
             if firstresult:  # first result hooks return a single value
-                results = outcome.get_result()
-                result = results[0] if results else None
-                outcome.force_result(result)
+                outcome = _Result(results[0] if results else None, excinfo)
+            else:
+                outcome = _Result(results, excinfo)
 
             # run all wrapper post-yield blocks
             for gen in reversed(teardowns):

From 5c6846f0a9632015e99661515d40f0f523350573 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <tgoodlet@gmail.com>
Date: Wed, 30 Aug 2017 16:53:56 -0400
Subject: [PATCH 4/4] Test forcing a result in a wrapper

---
 testing/test_hookrelay.py | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/testing/test_hookrelay.py b/testing/test_hookrelay.py
index 46ffadae..7d9b6f52 100644
--- a/testing/test_hookrelay.py
+++ b/testing/test_hookrelay.py
@@ -102,6 +102,41 @@ def hello(self, arg):
     assert res == 2
 
 
+def test_firstresult_force_result(pm):
+    """Verify forcing a result in a wrapper.
+    """
+    class Api(object):
+        @hookspec(firstresult=True)
+        def hello(self, arg):
+            "api hook 1"
+
+    pm.add_hookspecs(Api)
+
+    class Plugin1(object):
+        @hookimpl
+        def hello(self, arg):
+            return arg + 1
+
+    class Plugin2(object):
+        @hookimpl(hookwrapper=True)
+        def hello(self, arg):
+            assert arg == 3
+            outcome = yield
+            assert outcome.get_result() == 4
+            outcome.force_result(0)
+
+    class Plugin3(object):
+        @hookimpl
+        def hello(self, arg):
+            return None
+
+    pm.register(Plugin1())
+    pm.register(Plugin2())  # wrapper
+    pm.register(Plugin3())  # ignored since returns None
+    res = pm.hook.hello(arg=3)
+    assert res == 0  # this result is forced and not a list
+
+
 def test_firstresult_returns_none(pm):
     """If None results are returned by underlying implementations ensure
     the multi-call loop returns a None value.