From 62381125e74e62e051176afe602feb937dabcef8 Mon Sep 17 00:00:00 2001
From: Robert Holt <robert@robertholt.net>
Date: Mon, 19 Aug 2019 15:57:39 -0400
Subject: [PATCH 1/2] Fix self reference in function scoped fixtures

---
 AUTHORS                    |  1 +
 changelog/2270.bugfix.rst  |  1 +
 src/_pytest/fixtures.py    |  4 ++++
 testing/python/fixtures.py | 29 +++++++++++++++++++++++++++++
 4 files changed, 35 insertions(+)
 create mode 100644 changelog/2270.bugfix.rst

diff --git a/AUTHORS b/AUTHORS
index 88bbfe352..ad0c5c07b 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -209,6 +209,7 @@ Raphael Castaneda
 Raphael Pierzina
 Raquel Alegre
 Ravi Chandra
+Robert Holt
 Roberto Polli
 Roland Puntaier
 Romain Dorgueil
diff --git a/changelog/2270.bugfix.rst b/changelog/2270.bugfix.rst
new file mode 100644
index 000000000..45835deb6
--- /dev/null
+++ b/changelog/2270.bugfix.rst
@@ -0,0 +1 @@
+Fix ``self`` reference in function scoped fixtures that are in a plugin class
diff --git a/src/_pytest/fixtures.py b/src/_pytest/fixtures.py
index d5f9ad2d3..0640ebc90 100644
--- a/src/_pytest/fixtures.py
+++ b/src/_pytest/fixtures.py
@@ -897,6 +897,10 @@ def resolve_fixture_function(fixturedef, request):
         # request.instance so that code working with "fixturedef" behaves
         # as expected.
         if request.instance is not None:
+            if hasattr(fixturefunc, "__self__") and not isinstance(
+                request.instance, fixturefunc.__self__.__class__
+            ):
+                return fixturefunc
             fixturefunc = getimfunc(fixturedef.func)
             if fixturefunc != fixturedef.func:
                 fixturefunc = fixturefunc.__get__(request.instance)
diff --git a/testing/python/fixtures.py b/testing/python/fixtures.py
index 1f383e752..ee050b909 100644
--- a/testing/python/fixtures.py
+++ b/testing/python/fixtures.py
@@ -3945,6 +3945,35 @@ class TestScopeOrdering:
         reprec = testdir.inline_run()
         reprec.assertoutcome(passed=2)
 
+    def test_class_fixture_self_instance(self, testdir):
+        testdir.makeconftest(
+            """
+            import pytest
+
+            def pytest_configure(config):
+                config.pluginmanager.register(MyPlugin())
+
+            class MyPlugin():
+                def __init__(self):
+                    self.arg = 1
+
+                @pytest.fixture(scope='function')
+                def myfix(self):
+                    assert isinstance(self, MyPlugin)
+                    return self.arg
+        """
+        )
+
+        testdir.makepyfile(
+            """
+            class TestClass(object):
+                def test_1(self, myfix):
+                    assert myfix == 1
+        """
+        )
+        reprec = testdir.inline_run()
+        reprec.assertoutcome(passed=1)
+
 
 def test_call_fixture_function_error():
     """Check if an error is raised if a fixture function is called directly (#4545)"""

From 3ddbc7fb2a63f6ca505f64368d5bd4dd939f0ea9 Mon Sep 17 00:00:00 2001
From: Bruno Oliveira <bruno@esss.com.br>
Date: Fri, 30 Aug 2019 11:20:19 -0300
Subject: [PATCH 2/2] Improve CHANGELOG and add some comments

Ref: #5768
---
 changelog/2270.bugfix.rst  | 3 ++-
 src/_pytest/fixtures.py    | 2 ++
 testing/python/fixtures.py | 3 +++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/changelog/2270.bugfix.rst b/changelog/2270.bugfix.rst
index 45835deb6..0da084597 100644
--- a/changelog/2270.bugfix.rst
+++ b/changelog/2270.bugfix.rst
@@ -1 +1,2 @@
-Fix ``self`` reference in function scoped fixtures that are in a plugin class
+Fixed ``self`` reference in function-scoped fixtures defined plugin classes: previously ``self``
+would be a reference to a *test* class, not the *plugin* class.
diff --git a/src/_pytest/fixtures.py b/src/_pytest/fixtures.py
index 0640ebc90..a8da1beec 100644
--- a/src/_pytest/fixtures.py
+++ b/src/_pytest/fixtures.py
@@ -897,6 +897,8 @@ def resolve_fixture_function(fixturedef, request):
         # request.instance so that code working with "fixturedef" behaves
         # as expected.
         if request.instance is not None:
+            # handle the case where fixture is defined not in a test class, but some other class
+            # (for example a plugin class with a fixture), see #2270
             if hasattr(fixturefunc, "__self__") and not isinstance(
                 request.instance, fixturefunc.__self__.__class__
             ):
diff --git a/testing/python/fixtures.py b/testing/python/fixtures.py
index ee050b909..4f13dd245 100644
--- a/testing/python/fixtures.py
+++ b/testing/python/fixtures.py
@@ -3946,6 +3946,9 @@ class TestScopeOrdering:
         reprec.assertoutcome(passed=2)
 
     def test_class_fixture_self_instance(self, testdir):
+        """Check that plugin classes which implement fixtures receive the plugin instance
+        as self (see #2270).
+        """
         testdir.makeconftest(
             """
             import pytest