fix: don't assume Uproot is in global scope in TPython::Eval (#927)

* fix: don't assume Uproot is in global scope in TPython::Eval

* Unfortunately, this test does not trigger the bug (in main).

* Use TProfile3D for the test.

src/uproot/pyroot.py

@@ -101,15 +101,15 @@ class _Uproot_buffer_sizer : public TObject {
 
 char* _uproot_TMessage_reallocate(char* buffer, size_t newsize, size_t oldsize) {
     _Uproot_buffer_sizer* ptr = reinterpret_cast<_Uproot_buffer_sizer*>(
-        (void*)TPython::Eval("uproot.pyroot.pyroot_to_buffer.sizer")
+        (void*)TPython::Eval("__import__('uproot').pyroot.pyroot_to_buffer.sizer")
     );
     ptr->buffer = reinterpret_cast<size_t>(buffer);
     ptr->newsize = newsize;
     ptr->oldsize = oldsize;
 
-    TPython::Exec("uproot.pyroot.pyroot_to_buffer.reallocate()");
+    TPython::Exec("__import__('uproot').pyroot.pyroot_to_buffer.reallocate()");
 
-    TPyReturn out = TPython::Eval("uproot.pyroot.pyroot_to_buffer.buffer.ctypes.data");
+    TPyReturn out = TPython::Eval("__import__('uproot').pyroot.pyroot_to_buffer.buffer.ctypes.data");
     return reinterpret_cast<char*>((size_t)out);
 }
 

tests/test_0927-dont-assume-uproot-in-global-scope-in-TPython-Eval.py

@@ -0,0 +1,14 @@
+# BSD 3-Clause License; see https://github.com/scikit-hep/uproot5/blob/main/LICENSE
+
+import random
+import string
+
+import pytest
+
+ROOT = pytest.importorskip("ROOT")
+
+
+def test():
+    name = "".join(random.choices(string.ascii_lowercase, k=10))
+    h = ROOT.TProfile3D()
+    assert __import__("uproot").from_pyroot(h).values().shape == (1, 1, 1)