msubprojects: Fix unit tests on Windows

mesonbuild/msubprojects.py

@@ -1,5 +1,6 @@
 import os, subprocess
 import argparse
+from pathlib import Path
 
 from . import mlog
 from .mesonlib import quiet_git, verbose_git, GitException, Popen_safe, MesonException
@@ -338,7 +339,7 @@ def run(options):
     for wrap in wraps:
         if types and wrap.type not in types:
             continue
-        dirname = os.path.join(subprojects_dir, wrap.directory)
+        dirname = Path(subprojects_dir, wrap.directory).as_posix()
         if not options.subprojects_func(wrap, dirname, options):
             failures.append(wrap.name)
     if failures:

run_unittests.py

@@ -9125,13 +9125,13 @@ class SubprojectsCommandTests(BasePlatformTests):
 
         dummy_cmd = ['true']
         out = self._subprojects_cmd(['foreach'] + dummy_cmd)
-        self.assertEqual(ran_in(out), sorted(['./subprojects/sub_file', './subprojects/sub_git', './subprojects/sub_git_no_wrap']))
+        self.assertEqual(ran_in(out), sorted(['subprojects/sub_file', 'subprojects/sub_git', 'subprojects/sub_git_no_wrap']))
         out = self._subprojects_cmd(['foreach', '--types', 'git,file'] + dummy_cmd)
-        self.assertEqual(ran_in(out), sorted(['./subprojects/sub_file', './subprojects/sub_git']))
+        self.assertEqual(ran_in(out), sorted(['subprojects/sub_file', 'subprojects/sub_git']))
         out = self._subprojects_cmd(['foreach', '--types', 'file'] + dummy_cmd)
-        self.assertEqual(ran_in(out), ['./subprojects/sub_file'])
+        self.assertEqual(ran_in(out), ['subprojects/sub_file'])
         out = self._subprojects_cmd(['foreach', '--types', 'git'] + dummy_cmd)
-        self.assertEqual(ran_in(out), ['./subprojects/sub_git'])
+        self.assertEqual(ran_in(out), ['subprojects/sub_git'])
 
 def _clang_at_least(compiler, minver: str, apple_minver: str) -> bool:
     """