Add additional debugging tools

tests/CMakeLists.txt

@@ -231,7 +231,7 @@ else()
 endif()
 
 # A single command to compile and run the tests
-add_custom_target(pytest COMMAND ${PYTHON_EXECUTABLE} -m pytest ${PYBIND11_PYTEST_FILES}
+add_custom_target(pytest COMMAND ${PYTHON_EXECUTABLE} -u -m pytest ${PYBIND11_PYTEST_FILES}
                   DEPENDS ${test_targets} WORKING_DIRECTORY ${testdir} ${PYBIND11_USES_TERMINAL})
 
 if(PYBIND11_TEST_OVERRIDE)

tests/conftest.py

@@ -7,8 +7,10 @@
 import pytest
 import textwrap
 import difflib
+import functools
 import re
 import sys
+import trace
 import contextlib
 import platform
 import gc
@@ -190,6 +192,25 @@ def gc_collect():
     gc.collect()
 
 
+def traced(f):
+    """Decorator to trace the output of a given function (or test case).
+
+    Example:
+
+        @pytest.traced
+        def test_something():
+            print("Hello")
+
+    """
+    tracer = trace.Trace(trace=1, count=0, ignoredirs=["/usr", sys.prefix])
+
+    @functools.wraps(f)
+    def wrapped(*args, **kwargs):
+        return tracer.runfunc(f, *args, **kwargs)
+
+    return wrapped
+
+
 def pytest_configure():
     """Add import suppression and test requirements to `pytest` namespace"""
     try:
@@ -218,6 +239,7 @@ def pytest_configure():
     pytest.unsupported_on_py2 = skipif(sys.version_info.major < 3,
                                        reason="unsupported on Python 2.x")
     pytest.gc_collect = gc_collect
+    pytest.traced = traced
 
 
 def _test_import_pybind11():

tools/check-style.sh

@@ -14,11 +14,15 @@
 #
 # Invoke as: tools/check-style.sh
 #
+set -euo pipefail
+
+# TODO(eacousineau): Is there a way to have grep return 0 if there's no
+# matches, but report an error on other things (like syntax)?
 
 check_style_errors=0
 IFS=$'\n'
 
-found="$( GREP_COLORS='mt=41' GREP_COLOR='41' grep $'\t' include tests/*.{cpp,py,h} docs/*.rst -rn --color=always )"
+found="$( GREP_COLORS='mt=41' GREP_COLOR='41' grep $'\t' include tests/*.{cpp,py,h} docs/*.rst -rn --color=always || :)"
 if [ -n "$found" ]; then
     # The mt=41 sets a red background for matched tabs:
     echo -e '\033[31;01mError: found tab characters in the following files:\033[0m'
@@ -27,22 +31,22 @@ if [ -n "$found" ]; then
 fi
 
 
-found="$( grep -IUlr $'\r' include tests/*.{cpp,py,h} docs/*.rst --color=always )"
+found="$( grep -IUlr $'\r' include tests/*.{cpp,py,h} docs/*.rst --color=always || : )"
 if [ -n "$found" ]; then
     echo -e '\033[31;01mError: found CRLF characters in the following files:\033[0m'
     check_style_errors=1
     echo "$found" | sed -e 's/^/    /'
 fi
 
-found="$(GREP_COLORS='mt=41' GREP_COLOR='41' grep '[[:blank:]]\+$' include tests/*.{cpp,py,h} docs/*.rst -rn --color=always )"
+found="$(GREP_COLORS='mt=41' GREP_COLOR='41' grep '[[:blank:]]\+$' include tests/*.{cpp,py,h} docs/*.rst -rn --color=always || :)"
 if [ -n "$found" ]; then
     # The mt=41 sets a red background for matched trailing spaces
     echo -e '\033[31;01mError: found trailing spaces in the following files:\033[0m'
     check_style_errors=1
     echo "$found" | sed -e 's/^/    /'
 fi
 
-found="$(grep '\<\(if\|for\|while\|catch\)(\|){' include tests/*.{cpp,h} -rn --color=always)"
+found="$(grep '\<\(if\|for\|while\|catch\)(\|){' include tests/*.{cpp,h} -rn --color=always || :)"
 if [ -n "$found" ]; then
     echo -e '\033[31;01mError: found the following coding style problems:\033[0m'
     check_style_errors=1
@@ -67,4 +71,5 @@ if [ -n "$found" ]; then
     echo "$found"
 fi
 
+echo "Success - no errors found!"
 exit $check_style_errors