From 5ab312cc07408138e15b6b1f00ce45bf2d7e9319 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <tgoodlet@gmail.com>
Date: Tue, 29 Aug 2017 10:06:06 -0400
Subject: [PATCH 1/2] Add an edge case test for firstresult hooks

When calling a firstresult hook, if no implementation returns a non-None
value a bug is exposed in the new `_MultiCall` which assumes there will
be a least one result.
---
 testing/test_hookrelay.py | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/testing/test_hookrelay.py b/testing/test_hookrelay.py
index 9fbcd121..8d0447fd 100644
--- a/testing/test_hookrelay.py
+++ b/testing/test_hookrelay.py
@@ -92,3 +92,38 @@ def hello(self, arg):
     pm.register(Plugin3())  # None result is ignored
     res = pm.hook.hello(arg=3)
     assert res == 2
+
+
+def test_firstresult_returns_none(pm):
+    """If None results are returned by underlying implementations ensure
+    the multi-call loop returns a None value.
+    """
+    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 None
+
+    pm.register(Plugin1())
+    res = pm.hook.hello(arg=3)
+    assert res == None
+
+
+def test_firstresult_no_plugin(pm):
+    """If no implementations/plugins have been registered for a firstresult
+    hook the multi-call loop should return a None value.
+    """
+    class Api(object):
+        @hookspec(firstresult=True)
+        def hello(self, arg):
+            "api hook 1"
+
+    pm.add_hookspecs(Api)
+    res = pm.hook.hello(arg=3)
+    assert res == None

From f1a227086408437dd9e52350200bdabc8e6fe22f Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <tgoodlet@gmail.com>
Date: Tue, 29 Aug 2017 10:09:02 -0400
Subject: [PATCH 2/2] Handle firstresult hooks that return None

Only return the first result when at least one result has been returned
by underlying hook implementations.

Fixes #68
---
 pluggy/callers.py         | 3 ++-
 testing/test_hookrelay.py | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/pluggy/callers.py b/pluggy/callers.py
index abe36e78..c5934b96 100644
--- a/pluggy/callers.py
+++ b/pluggy/callers.py
@@ -107,7 +107,8 @@ def execute(self):
                     pass
 
             if firstresult:
-                return outcome.get_result()[0]
+                result = outcome.get_result()
+                return result[0] if result else None
 
             return outcome.get_result()
 
diff --git a/testing/test_hookrelay.py b/testing/test_hookrelay.py
index 8d0447fd..3653151b 100644
--- a/testing/test_hookrelay.py
+++ b/testing/test_hookrelay.py
@@ -112,7 +112,7 @@ def hello(self, arg):
 
     pm.register(Plugin1())
     res = pm.hook.hello(arg=3)
-    assert res == None
+    assert res is None
 
 
 def test_firstresult_no_plugin(pm):
@@ -126,4 +126,4 @@ def hello(self, arg):
 
     pm.add_hookspecs(Api)
     res = pm.hook.hello(arg=3)
-    assert res == None
+    assert res is None