test(e2e): reproduce py_binary execve failure under bazel run (runfiles discovery)

e2e/cases/run-runfiles-discovery/BUILD.bazel

@@ -0,0 +1,23 @@
+load("@aspect_rules_py//py:defs.bzl", "py_binary")
+load("@rules_shell//shell:sh_test.bzl", "sh_test")
+
+py_binary(
+    name = "hello",
+    srcs = ["hello.py"],
+    main = "hello.py",
+)
+
+# Reproduces a py_binary launcher (hermetic_launcher 0.0.9) failing under
+# `bazel run` / direct exec when RUNFILES_DIR is not pre-set: the launcher
+# cannot self-locate its `.runfiles` dir and aborts with
+# "execve failed with errno 2". `bazel test` masks this by setting RUNFILES_DIR.
+#
+# Tagged `manual` so it stays out of the default `//...` gate until the launcher
+# fix lands; run explicitly with `bazel test //cases/run-runfiles-discovery:runs_via_bazel_run`.
+sh_test(
+    name = "runs_via_bazel_run",
+    srcs = ["run_it.sh"],
+    args = ["$(rootpath :hello)"],
+    data = [":hello"],
+    tags = ["manual"],
+)

e2e/cases/run-runfiles-discovery/hello.py

@@ -0,0 +1 @@
+print("Hello, world!")

e2e/cases/run-runfiles-discovery/run_it.sh

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+#!/usr/bin/env bash
+# Regression test: a py_binary must be runnable via `bazel run` (and directly),
+# where the launcher discovers its own `.runfiles` dir from argv[0] rather than
+# relying on a pre-set RUNFILES_DIR.
+#
+# `bazel test` sets RUNFILES_DIR for the test, which masks the bug. We reproduce
+# the `bazel run` / direct-exec path by UNSETTING the runfiles env vars before
+# invoking the binary, forcing the launcher to self-locate its runfiles.
+#
+# BUG (hermetic_launcher 0.0.9): without RUNFILES_DIR/RUNFILES_MANIFEST_FILE set,
+# the launcher fails to resolve the embedded venv-python rlocation and aborts
+# with "execve failed with errno 2". Works when RUNFILES_DIR is pre-set.
+set -euo pipefail
+
+bin="$1"
+unset RUNFILES_DIR RUNFILES_MANIFEST_FILE JAVA_RUNFILES || true
+output="$("$bin")"
+if [[ "$output" != *"Hello, world!"* ]]; then
+  echo "FAIL: expected 'Hello, world!', got: $output" >&2
+  exit 1
+fi
+echo "PASS: py_binary ran via self-located runfiles"