bpo-37935: Added tests for os.walk(), glob.iglob() and Path.glob() (GH-15956)

Test that they do not keep too many file descriptors open for the host OS in a reasonable test scenario.

See [bpo-37935](https://bugs.python.org/issue37935).

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/test/test_glob.py b/Lib/test/test_glob.py
index 767bd37..cba8c7c 100644
--- a/Lib/test/test_glob.py
+++ b/Lib/test/test_glob.py
@@ -264,6 +264,23 @@ class GlobTests(unittest.TestCase):
                 expect += [join('sym3', 'EF')]
             eq(glob.glob(join('**', 'EF'), recursive=True), expect)
 
+    def test_glob_many_open_files(self):
+        depth = 30
+        base = os.path.join(self.tempdir, 'deep')
+        p = os.path.join(base, *(['d']*depth))
+        os.makedirs(p)
+        pattern = os.path.join(base, *(['*']*depth))
+        iters = [glob.iglob(pattern, recursive=True) for j in range(100)]
+        for it in iters:
+            self.assertEqual(next(it), p)
+        pattern = os.path.join(base, '**', 'd')
+        iters = [glob.iglob(pattern, recursive=True) for j in range(100)]
+        p = base
+        for i in range(depth):
+            p = os.path.join(p, 'd')
+            for it in iters:
+                self.assertEqual(next(it), p)
+
 
 @skip_unless_symlink
 class SymlinkLoopGlobTests(unittest.TestCase):