From e1a21e46b00959b8831b195c524bbf504e458bec Mon Sep 17 00:00:00 2001
From: Bruno Oliveira <nicoddemus@gmail.com>
Date: Sat, 30 May 2020 20:14:26 -0300
Subject: [PATCH] Merge pull request #7220 from nicoddemus/issue-6428

---
 changelog/6428.bugfix.rst |  2 ++
 src/_pytest/nodes.py      | 10 ++++++++--
 testing/test_nodes.py     | 27 +++++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 2 deletions(-)
 create mode 100644 changelog/6428.bugfix.rst

diff --git a/changelog/6428.bugfix.rst b/changelog/6428.bugfix.rst
new file mode 100644
index 00000000000..581b2b7cece
--- /dev/null
+++ b/changelog/6428.bugfix.rst
@@ -0,0 +1,2 @@
+Paths appearing in error messages are now correct in case the current working directory has
+changed since the start of the session.
diff --git a/src/_pytest/nodes.py b/src/_pytest/nodes.py
index 7edea1e976c..6f22a8daaa0 100644
--- a/src/_pytest/nodes.py
+++ b/src/_pytest/nodes.py
@@ -29,6 +29,7 @@
 from _pytest.mark.structures import MarkDecorator
 from _pytest.mark.structures import NodeKeywords
 from _pytest.outcomes import fail
+from _pytest.pathlib import Path
 from _pytest.store import Store
 
 if TYPE_CHECKING:
@@ -348,9 +349,14 @@ def _repr_failure_py(
         else:
             truncate_locals = True
 
+        # excinfo.getrepr() formats paths relative to the CWD if `abspath` is False.
+        # It is possible for a fixture/test to change the CWD while this code runs, which
+        # would then result in the user seeing confusing paths in the failure message.
+        # To fix this, if the CWD changed, always display the full absolute path.
+        # It will be better to just always display paths relative to invocation_dir, but
+        # this requires a lot of plumbing (#6428).
         try:
-            os.getcwd()
-            abspath = False
+            abspath = Path(os.getcwd()) != Path(self.config.invocation_dir)
         except OSError:
             abspath = True
 
diff --git a/testing/test_nodes.py b/testing/test_nodes.py
index dbb3e2e8f64..5bd31b34261 100644
--- a/testing/test_nodes.py
+++ b/testing/test_nodes.py
@@ -58,3 +58,30 @@ class FakeSession:
 
     outside = py.path.local("/outside")
     assert nodes._check_initialpaths_for_relpath(FakeSession, outside) is None
+
+
+def test_failure_with_changed_cwd(testdir):
+    """
+    Test failure lines should use absolute paths if cwd has changed since
+    invocation, so the path is correct (#6428).
+    """
+    p = testdir.makepyfile(
+        """
+        import os
+        import pytest
+
+        @pytest.fixture
+        def private_dir():
+            out_dir = 'ddd'
+            os.mkdir(out_dir)
+            old_dir = os.getcwd()
+            os.chdir(out_dir)
+            yield out_dir
+            os.chdir(old_dir)
+
+        def test_show_wrong_path(private_dir):
+            assert False
+    """
+    )
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines([str(p) + ":*: AssertionError", "*1 failed in *"])