change code to install debug in fixture

devtools/__main__.py

@@ -8,13 +8,17 @@
 # language=python
 install_code = """
 # add devtools `debug` function to builtins
-import builtins
-try:
-    from devtools import debug
-except ImportError:
-    pass
-else:
-    setattr(builtins, 'debug', debug)
+import sys
+# we don't install here for pytest as it breaks pytest, it is
+# installed later by a pytest fixture
+if not sys.argv[0].endswith('pytest'):
+    import builtins
+    try:
+        from devtools import debug
+    except ImportError:
+        pass
+    else:
+        setattr(builtins, 'debug', debug)
 """
 
 

devtools/pytest_plugin.py

@@ -1,6 +1,7 @@
 from __future__ import annotations as _annotations
 
 import ast
+import builtins
 import sys
 import textwrap
 from contextvars import ContextVar
@@ -15,6 +16,8 @@
 import pytest
 from executing import Source
 
+from . import debug
+
 if TYPE_CHECKING:
     pass
 
@@ -79,7 +82,9 @@ def pytest_addoption(parser: Any) -> None:
 @pytest.fixture(scope='session', autouse=True)
 def insert_assert_add_to_builtins() -> None:
     try:
-        __builtins__['insert_assert'] = insert_assert
+        setattr(builtins, 'insert_assert', insert_assert)
+        # we also install debug here since the default script doesn't install it
+        setattr(builtins, 'debug', debug)
     except TypeError:
         # happens on pypy
         pass