Make sure xeus-python kernel emscripten build runs after the FederatedExtension addon

jupyterlite_xeus_python/env_build_addon.py

@@ -16,6 +16,8 @@
     ENV_EXTENSIONS,
 )
 
+JUPYTERLITE_XEUS_PYTHON_DEBUG = 'JUPYTERLITE_XEUS_PYTHON_DEBUG'
+
 JUPYTERLITE_XEUS_PYTHON = "@jupyterlite/xeus-python-kernel"
 
 # TODO Make this configurable
@@ -62,7 +64,7 @@ def from_string(self, s):
 
 class XeusPythonEnv(FederatedExtensionAddon):
 
-    __all__ = ["pre_build", "post_build"]
+    __all__ = ["post_build"]
 
     xeus_python_version = Unicode().tag(
         config=True, description="The xeus-python version to use"
@@ -102,7 +104,7 @@ def __init__(self, *args, **kwargs):
 
         self.orig_config = os.environ.get("CONDARC")
 
-    def pre_build(self, manager):
+    def post_build(self, manager):
         """yield a doit task to create the emscripten-32 env and grab anything we need from it"""
         # Install the jupyterlite-xeus-python ourselves
         for pkg_json in self.env_extensions(ENV_EXTENSIONS):
@@ -138,18 +140,14 @@ def pre_build(self, manager):
         # (make jupyterlite-xeus-python extension somewhat configurable?)
         dest = self.output_extensions / "@jupyterlite" / "xeus-python-kernel" / "static"
 
-        task_dep = ["pre_build:federated_extensions:*"]
-
         for file in ["python_data.js", "python_data.data"]:
             yield dict(
-                task_dep=task_dep,
                 name=f"xeus:copy:{file}",
                 actions=[(self.copy_one, [Path(self.cwd.name) / file, dest / file])],
             )
 
         for file in ["xpython_wasm.js", "xpython_wasm.wasm"]:
             yield dict(
-                task_dep=task_dep,
                 name=f"xeus:copy:{file}",
                 actions=[
                     (
@@ -162,6 +160,16 @@ def pre_build(self, manager):
                 ],
             )
 
+        if not os.environ.get(JUPYTERLITE_XEUS_PYTHON_DEBUG, False):
+            # Cleanup
+            shutil.rmtree(self.cwd.name, ignore_errors=True)
+            shutil.rmtree(self.root_prefix, ignore_errors=True)
+
+            if self.orig_config is not None:
+                os.environ["CONDARC"] = self.orig_config
+            elif "CONDARC" in os.environ:
+                del os.environ["CONDARC"]
+
     def create_env(self):
         """Create the xeus-python emscripten-32 env with either mamba, micromamba or conda."""
         if MAMBA_PYTHON_AVAILABLE:
@@ -234,22 +242,6 @@ def _create_config(self):
             fobj.write(f"subdir: {PLATFORM}")
         os.environ["CONDARC"] = str(self.prefix_path / ".condarc")
 
-    def post_build(self, manager):
-        """Cleanup"""
-        # Bail early if there is nothing to do
-        if not self.packages and not self.xeus_python_version:
-            return []
-
-        shutil.rmtree(self.cwd.name, ignore_errors=True)
-        shutil.rmtree(self.root_prefix, ignore_errors=True)
-
-        if self.orig_config is not None:
-            os.environ["CONDARC"] = self.orig_config
-        elif "CONDARC" in os.environ:
-            del os.environ["CONDARC"]
-
-        return []
-
     def safe_copy_extension(self, pkg_json):
         """Copy a labextension, and overwrite it
         if it's already in the output

tests/test_xeus_python_env.py

@@ -6,7 +6,7 @@
 
 from jupyterlite.app import LiteStatusApp
 
-from jupyterlite_xeus_python.env_build_addon import XeusPythonEnv
+from jupyterlite_xeus_python.env_build_addon import XeusPythonEnv, JUPYTERLITE_XEUS_PYTHON_DEBUG
 
 
 def test_python_env():
@@ -17,7 +17,9 @@ def test_python_env():
     addon = XeusPythonEnv(manager)
     addon.packages = ["numpy", "ipyleaflet"]
 
-    for step in addon.pre_build(manager):
+    os.environ[JUPYTERLITE_XEUS_PYTHON_DEBUG] = "True"
+
+    for step in addon.post_build(manager):
         pass
 
     # Check env