tests: Add rust-as-a-module test

Taken and simplified from shell test.

tests/rust_libs/Makefile

@@ -0,0 +1,13 @@
+include ../Makefile.tests_common
+
+USEMODULE += shell
+USEMODULE += shell_commands
+USEMODULE += rust_module_examples_shell_commands
+
+FEATURES_REQUIRED += rust_target
+
+# Currently unknown, something related to the LED_PORT definition that doesn't
+# pass C2Rust's transpilation
+BOARD_BLACKLIST := ek-lm4f120xl
+
+include $(RIOTBASE)/Makefile.include

tests/rust_libs/main.c

@@ -0,0 +1 @@
+../shell/main.c

tests/rust_libs/tests/01-run.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2017 Alexandre Abadie <[email protected]>
+#               2022 Christian Amsüss <[email protected]>
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+import sys
+import os
+from testrunner import run
+
+
+EXPECTED_HELP = (
+    'Command              Description',
+    '---------------------------------------',
+    'bufsize              Get the shell\'s buffer size',
+    'start_test           starts a test',
+    'end_test             ends a test',
+    'echo                 prints the input command',
+    'empty                print nothing on command',
+    'reboot               Reboot the node',
+    'version              Prints current RIOT_VERSION',
+    'pm                   interact with layered PM subsystem',
+    # That's what we're here for, the rest is what happens to be configured in
+    # the shell test this is derived from
+    'ps.rs                List the processes',
+    'xfa_test1            xfa test command 1',
+    'xfa_test2            xfa test command 2',
+)
+
+EXPECTED_PSRS = (
+    'pri  7.*Running',
+)
+
+PROMPT = '> '
+
+CMDS = (
+    ('start_test', '[TEST_START]'),
+
+    # test default commands
+    ('help', EXPECTED_HELP),
+    ('ps.rs', EXPECTED_PSRS),
+
+    ('end_test', '[TEST_END]'),
+)
+
+CMDS_REGEX = {'ps.rs'}
+
+def check_cmd(child, cmd, expected):
+    regex = cmd in CMDS_REGEX
+    child.expect(PROMPT)
+    child.sendline(cmd)
+    for line in expected:
+        if regex:
+            child.expect(line)
+        else:
+            child.expect_exact(line)
+
+def testfunc(child):
+    # loop other defined commands and expected output
+    for cmd, expected in CMDS:
+        check_cmd(child, cmd, expected)
+
+
+if __name__ == "__main__":
+    sys.exit(run(testfunc))