tests: Add rust-as-a-module test

Taken and simplified from shell test.

tests/rust_libs/Makefile

@@ -0,0 +1,12 @@
+include ../Makefile.tests_common
+
+USEMODULE += shell
+USEMODULE += shell_democommands
+
+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/Makefile.ci

@@ -0,0 +1,10 @@
+BOARD_INSUFFICIENT_MEMORY := \
+    nucleo-f031k6 \
+    nucleo-f042k6 \
+    nucleo-l011k4 \
+    nucleo-l031k6 \
+    samd10-xmini \
+    stk3200 \
+    stm32f030f4-demo \
+    stm32g0316-disco \
+    #

tests/rust_libs/main.c

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

tests/rust_libs/tests/01-run.py

@@ -0,0 +1,59 @@
+#!/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
+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',
+    'hello_world          Print a greeting',
+    'xfa_test1            xfa test command 1',
+    'xfa_test2            xfa test command 2',
+)
+
+PROMPT = '> '
+
+CMDS = (
+    ('start_test', '[TEST_START]'),
+
+    # test default commands
+    ('help', EXPECTED_HELP),
+
+    ('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))