From ac3523132d6d6eee980dfe53bcc6671323a78155 Mon Sep 17 00:00:00 2001
From: Joe Rickerby <joerick@mac.com>
Date: Thu, 13 Aug 2020 11:46:39 +0100
Subject: [PATCH 1/2] Add troubleshoot test

---
 cibuildwheel/linux.py        |  4 ++--
 test/test_troubleshooting.py | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 test/test_troubleshooting.py

diff --git a/cibuildwheel/linux.py b/cibuildwheel/linux.py
index a328c608..6f4698b5 100644
--- a/cibuildwheel/linux.py
+++ b/cibuildwheel/linux.py
@@ -233,7 +233,7 @@ def build(options: BuildOptions) -> None:
 
 
 def troubleshoot(package_dir: Path, error: Exception) -> None:
-    if (isinstance(error, subprocess.CalledProcessError) and 'exec' in error.cmd):
+    if (isinstance(error, subprocess.CalledProcessError) and error.cmd[0:2] == ['pip', 'wheel']):
         # the bash script failed
         print('Checking for common errors...')
         so_files = list(package_dir.glob('**/*.so'))
@@ -247,7 +247,7 @@ def troubleshoot(package_dir: Path, error: Exception) -> None:
 
                   If you're using Cython and have previously done an in-place build,
                   remove those build files (*.so and *.c) before starting cibuildwheel.
-            '''))
+            '''), file=sys.stderr)
 
             print('  Files detected:')
             print('\n'.join([f'    {f}' for f in so_files]))
diff --git a/test/test_troubleshooting.py b/test/test_troubleshooting.py
new file mode 100644
index 00000000..3d07dfb5
--- /dev/null
+++ b/test/test_troubleshooting.py
@@ -0,0 +1,28 @@
+import subprocess
+import pytest
+from .test_projects import TestProject
+from . import utils
+
+so_file_project = TestProject()
+
+so_file_project.files['libnothing.so'] = ''
+
+so_file_project.files['setup.py'] = '''
+raise Exception('this build will fail')
+'''
+
+
+def test_failed_project_with_so_files(tmp_path, capfd):
+    if utils.platform != 'linux':
+        pytest.skip('this test is only relevant to the linux build')
+
+    project_dir = tmp_path / 'project'
+    so_file_project.generate(project_dir)
+
+    with pytest.raises(subprocess.CalledProcessError):
+        utils.cibuildwheel_run(project_dir)
+
+    captured = capfd.readouterr()
+    print('out', captured.out)
+    print('err', captured.err)
+    assert "NOTE: Shared object (.so) files found in this project." in captured.err

From f19c6065738d35601137da3b2aa3769bcc8e7989 Mon Sep 17 00:00:00 2001
From: Joe Rickerby <joerick@mac.com>
Date: Thu, 13 Aug 2020 11:50:17 +0100
Subject: [PATCH 2/2] Fix comment

---
 cibuildwheel/linux.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cibuildwheel/linux.py b/cibuildwheel/linux.py
index 6f4698b5..bb80fda8 100644
--- a/cibuildwheel/linux.py
+++ b/cibuildwheel/linux.py
@@ -234,7 +234,7 @@ def build(options: BuildOptions) -> None:
 
 def troubleshoot(package_dir: Path, error: Exception) -> None:
     if (isinstance(error, subprocess.CalledProcessError) and error.cmd[0:2] == ['pip', 'wheel']):
-        # the bash script failed
+        # the 'pip wheel' step failed.
         print('Checking for common errors...')
         so_files = list(package_dir.glob('**/*.so'))