[Exp PyROOT] Add test for len in TArray and subclasses

bindings/pyroot_experimental/PyROOT/test/CMakeLists.txt

@@ -19,3 +19,6 @@ ROOT_ADD_PYUNITTEST(pyroot_pyz_ttree_branch ttree_branch.py
 
 # TCollection and subclasses pythonizations
 ROOT_ADD_PYUNITTEST(pyroot_pyz_tcollection_len tcollection_len.py)
+
+# TArray and subclasses pythonizations
+ROOT_ADD_PYUNITTEST(pyroot_pyz_tarray_len tarray_len.py)

bindings/pyroot_experimental/PyROOT/test/tarray_len.py

+import unittest
+
+import ROOT
+
+
+class TArrayLen(unittest.TestCase):
+    """
+    Test for the pythonization that allows to access the number of elements of a
+    TArray (or subclass) by calling `len` on it.
+    """
+
+    num_elems = 3
+
+    # Helpers
+    def check_len(self, a):
+        self.assertEqual(len(a), self.num_elems)
+        self.assertEqual(len(a), a.GetSize())
+
+    # Tests
+    def test_tarrayi(self):
+        self.check_len(ROOT.TArrayI(self.num_elems))
+
+    def test_tarrayd(self):
+        self.check_len(ROOT.TArrayD(self.num_elems))