Improve import sanity test output handling. (#52136)

Handling of unexpected output for the following is improved:

- stdout
- stderr
- warnings

test/sanity/import/importer.py

@@ -8,6 +8,7 @@ import os
 import re
 import sys
 import traceback
+import warnings
 
 try:
     import importlib.util
@@ -146,6 +147,7 @@ class Capture(object):
     def __init__(self):
         self.stdout = StringIO()
         self.stderr = StringIO()
+        self.warnings = []
 
 
 def capture_report(path, capture, messages):
@@ -155,11 +157,37 @@ def capture_report(path, capture, messages):
     :type messages: set[str]
     """
     if capture.stdout.getvalue():
-        message = '%s:%d:%d: %s: %s' % (path, 0, 0, 'Output', 'Import resulted in output to stdout.')
+        first = capture.stdout.getvalue().strip().splitlines()[0].strip()
+        message = '%s:%d:%d: %s: %s' % (path, 0, 0, 'StandardOutputUsed', first)
         report_message(message, messages)
 
     if capture.stderr.getvalue():
-        message = '%s:%d:%d: %s: %s' % (path, 0, 0, 'Output', 'Import resulted in output to stderr.')
+        first = capture.stderr.getvalue().strip().splitlines()[0].strip()
+        message = '%s:%d:%d: %s: %s' % (path, 0, 0, 'StandardErrorUsed', first)
+        report_message(message, messages)
+
+    for warning in capture.warnings:
+        msg = re.sub(r'\s+', ' ', '%s' % warning.message).strip()
+
+        filepath = os.path.relpath(warning.filename)
+        lineno = warning.lineno
+
+        import_dir = 'test/runner/.tox/import/'
+        minimal_dir = 'test/runner/.tox/minimal-'
+
+        if filepath.startswith('../') or filepath.startswith(minimal_dir):
+            # The warning occurred outside our source tree.
+            # The best we can do is to report the file which was tested that triggered the warning.
+            # If the responsible import is in shared code this warning will be repeated for each file tested which imports the shared code.
+            msg += ' (in %s:%d)' % (warning.filename, warning.lineno)
+            filepath = path
+            lineno = 0
+        elif filepath.startswith(import_dir):
+            # Strip the import dir from warning paths in shared code.
+            # Needed when warnings occur in places like module_utils but are caught by the modules importing the module_utils.
+            filepath = os.path.relpath(filepath, import_dir)
+
+        message = '%s:%d:%d: %s: %s' % (filepath, lineno, 0, warning.category.__name__, msg)
         report_message(message, messages)
 
 
@@ -184,11 +212,14 @@ def capture_output(capture):
     sys.stdout = capture.stdout
     sys.stderr = capture.stderr
 
-    try:
-        yield
-    finally:
-        sys.stdout = old_stdout
-        sys.stderr = old_stderr
+    with warnings.catch_warnings(record=True) as captured_warnings:
+        try:
+            yield
+        finally:
+            capture.warnings = captured_warnings
+
+            sys.stdout = old_stdout
+            sys.stderr = old_stderr
 
 
 if __name__ == '__main__':