run_in_pyodide: Add handling for when requested packages are not built

* When running outside of pytest, raise a RuntimeError
* When running in pytest locally, skip the test
* When running in pytest in CI, fail the test

Can configure whether we want the test to be skipped or failed with
the `skip_if_not_all_built` argument.

Author: hoodmane

pytest_pyodide/decorator.py

@@ -1,5 +1,6 @@
 import ast
 import functools
+import os
 import pickle
 import sys
 from base64 import b64decode, b64encode
@@ -381,6 +382,7 @@ def __new__(cls, function: Callable | None = None, /, **kwargs):
     def __init__(
         self,
         packages: Collection[str] = (),
+        skip_if_not_all_built: bool = "CI" in os.environ,
         pytest_assert_rewrites: bool = True,
         *,
         _force_assert_rewrites: bool = False,
@@ -403,6 +405,15 @@ def __init__(
             when an assertion fails, but requires us to load pytest.
         """
 
+        unbuilt = sorted(pkg for pkg in packages if not package_is_built(pkg))
+        if unbuilt:
+            msg = "Requires unbuilt packages: " + ", ".join(unbuilt)
+            if "PYTEST_CURRENT_TEST" not in os.environ:
+                raise RuntimeError(msg)
+            if skip_if_not_all_built:
+                pytest.skip(msg)
+            pytest.fail(msg)
+
         self._pkgs = list(packages)
         pytest_assert_rewrites = _force_assert_rewrites or (
             pytest_assert_rewrites and package_is_built("pytest")