better error handling for managed site installations

src/maturin_import_hook/__main__.py

@@ -8,6 +8,7 @@
 from pathlib import Path
 from typing import Optional
 
+from maturin_import_hook import project_importer, rust_file_importer
 from maturin_import_hook._building import get_default_build_dir
 from maturin_import_hook._site import (
     get_sitecustomize_path,
@@ -94,6 +95,8 @@ def _action_site_info(format_name: str) -> None:
             "usercustomize_path": str(usercustomize_path),
             "usercustomize_exists": usercustomize_path.exists(),
             "usercustomize_import_hook_installed": has_automatic_installation(usercustomize_path),
+            "project_importer_installed": project_importer.is_installed(),
+            "rust_file_importer_installed": rust_file_importer.is_installed(),
         },
         format_name,
     )
@@ -108,8 +111,21 @@ def _action_site_install(
     enable_rs_file_importer: bool,
     detect_uv: bool,
 ) -> None:
-    module_path = get_usercustomize_path() if user else get_sitecustomize_path()
-    insert_automatic_installation(module_path, force, args, enable_project_importer, enable_rs_file_importer, detect_uv)
+    if user:
+        module_path = get_usercustomize_path()
+        uninstall_command = "python -m maturin_import_hook site uninstall --user"
+    else:
+        module_path = get_sitecustomize_path()
+        uninstall_command = "python -m maturin_import_hook site uninstall"
+    insert_automatic_installation(
+        module_path,
+        uninstall_command,
+        force,
+        args,
+        enable_project_importer,
+        enable_rs_file_importer,
+        detect_uv,
+    )
 
 
 def _action_site_uninstall(*, user: bool) -> None:

src/maturin_import_hook/_site.py

@@ -9,27 +9,26 @@
 from maturin_import_hook._logging import logger
 from maturin_import_hook.settings import MaturinSettings
 
-MANAGED_INSTALL_START = "# <maturin_import_hook>"
+MANAGED_INSTALL_START = "# <maturin_import_hook>\n"
 MANAGED_INSTALL_END = "# </maturin_import_hook>\n"
-MANAGED_INSTALL_COMMENT = """
+MANAGED_INSTALL_TEMPLATE = """\
 # the following installs the maturin import hook during startup.
 # see: `python -m maturin_import_hook site`
-"""
-
-INSTALL_TEMPLATE = """\
 try:
     import maturin_import_hook
     from maturin_import_hook.settings import MaturinSettings
-except ImportError:
-    pass
-else:
     maturin_import_hook.install(
         settings=MaturinSettings(
             {settings}
         ),
         enable_project_importer={enable_project_importer},
         enable_rs_file_importer={enable_rs_file_importer},
     )
+except Exception as e:
+    raise RuntimeError(
+        f"{{e}}\\n>> ERROR in managed maturin_import_hook installation. "
+        "Remove with `{uninstall_command}`\\n",
+    )
 """
 
 
@@ -104,6 +103,7 @@ def _should_use_uv() -> bool:
 
 def insert_automatic_installation(
     module_path: Path,
+    uninstall_command: str,
     force: bool,
     args: Optional[str],
     enable_project_importer: bool,
@@ -142,11 +142,11 @@ def insert_automatic_installation(
 
     parts.extend([
         MANAGED_INSTALL_START,
-        MANAGED_INSTALL_COMMENT,
-        INSTALL_TEMPLATE.format(
+        MANAGED_INSTALL_TEMPLATE.format(
             settings=",\n            ".join(f"{k}={v!r}" for k, v in non_default_settings.items()),
             enable_project_importer=repr(enable_project_importer),
             enable_rs_file_importer=repr(enable_rs_file_importer),
+            uninstall_command=uninstall_command,
         ),
         MANAGED_INSTALL_END,
     ])

tests/test_import_hook/test_site.py

@@ -26,6 +26,7 @@ def test_automatic_site_installation(tmp_path: Path) -> None:
 
     insert_automatic_installation(
         sitecustomize,
+        "<uninstall>",
         force=False,
         args=None,
         enable_project_importer=True,
@@ -36,6 +37,7 @@ def test_automatic_site_installation(tmp_path: Path) -> None:
     with capture_logs() as cap:
         insert_automatic_installation(
             sitecustomize,
+            "<uninstall>",
             force=False,
             args=None,
             enable_project_importer=True,
@@ -56,16 +58,18 @@ def test_automatic_site_installation(tmp_path: Path) -> None:
     try:
         import maturin_import_hook
         from maturin_import_hook.settings import MaturinSettings
-    except ImportError:
-        pass
-    else:
         maturin_import_hook.install(
             settings=MaturinSettings(
                 color=True
             ),
             enable_project_importer=True,
             enable_rs_file_importer=True,
         )
+    except Exception as e:
+        raise RuntimeError(
+            f"{e}\\n>> ERROR in managed maturin_import_hook installation. "
+            "Remove with `<uninstall>`\\n",
+        )
     # </maturin_import_hook>
     """)
 
@@ -107,6 +111,7 @@ def test_automatic_site_installation_force_overwrite(tmp_path: Path) -> None:
 
     insert_automatic_installation(
         sitecustomize,
+        "<uninstall>",
         force=False,
         args=None,
         enable_project_importer=True,
@@ -119,6 +124,7 @@ def test_automatic_site_installation_force_overwrite(tmp_path: Path) -> None:
     with capture_logs() as cap:
         insert_automatic_installation(
             sitecustomize,
+            "<uninstall>",
             force=True,
             args="--release",
             enable_project_importer=True,
@@ -142,9 +148,6 @@ def test_automatic_site_installation_force_overwrite(tmp_path: Path) -> None:
     try:
         import maturin_import_hook
         from maturin_import_hook.settings import MaturinSettings
-    except ImportError:
-        pass
-    else:
         maturin_import_hook.install(
             settings=MaturinSettings(
                 release=True,
@@ -153,6 +156,11 @@ def test_automatic_site_installation_force_overwrite(tmp_path: Path) -> None:
             enable_project_importer=True,
             enable_rs_file_importer=True,
         )
+    except Exception as e:
+        raise RuntimeError(
+            f"{e}\\n>> ERROR in managed maturin_import_hook installation. "
+            "Remove with `<uninstall>`\\n",
+        )
     # </maturin_import_hook>
     """)
 
@@ -165,6 +173,7 @@ def test_automatic_site_installation_invalid_args(tmp_path: Path) -> None:
     with pytest.raises(ValueError, match="argument parser error"):
         insert_automatic_installation(
             sitecustomize,
+            "<uninstall>",
             force=False,
             args="--foo",
             enable_project_importer=True,
@@ -178,6 +187,7 @@ def test_automatic_site_installation_empty(tmp_path: Path) -> None:
     sitecustomize = tmp_path / "sitecustomize.py"
     insert_automatic_installation(
         sitecustomize,
+        "<uninstall>",
         force=False,
         args=None,
         enable_project_importer=True,
@@ -192,16 +202,18 @@ def test_automatic_site_installation_empty(tmp_path: Path) -> None:
     try:
         import maturin_import_hook
         from maturin_import_hook.settings import MaturinSettings
-    except ImportError:
-        pass
-    else:
         maturin_import_hook.install(
             settings=MaturinSettings(
                 color=True
             ),
             enable_project_importer=True,
             enable_rs_file_importer=True,
         )
+    except Exception as e:
+        raise RuntimeError(
+            f"{e}\\n>> ERROR in managed maturin_import_hook installation. "
+            "Remove with `<uninstall>`\\n",
+        )
     # </maturin_import_hook>
     """)