Add a hook for tzdata

Collects timezone data files as well as submodules that are required
for proper timezone data discovery via importlib.resources.

Add a test that simulates the data loading as performed by zoneinfo
and backports.zoneinfo.

news/339.new.0.rst

@@ -0,0 +1 @@
+Add hook for ``tzdata``.

requirements-test-libraries.txt

@@ -1,3 +1,6 @@
+# Backport of importlib.resources for python 3.8 and earlier.
+importlib_resources==5.3.0; python_version < '3.9'
+
 # ------------------ LIBRARIES ------------------ #
 # TODO: Add most of the libraries we have hooks for, and write tests
 av==8.0.3
@@ -58,6 +61,7 @@ swagger-spec-validator==2.7.3
 thinc==8.0.10
 timezonefinder==5.2.0
 tableauhyperapi==0.0.13617
+tzdata==2021.5
 Unidecode==1.3.2
 web3==5.24.0
 websockets==10.0; python_version >= '3.7'

src/_pyinstaller_hooks_contrib/hooks/stdhooks/hook-tzdata.py

@@ -0,0 +1,22 @@
+# ------------------------------------------------------------------
+# Copyright (c) 2021 PyInstaller Development Team.
+#
+# This file is distributed under the terms of the GNU General Public
+# License (version 2.0 or later).
+#
+# The full license is available in LICENSE.GPL.txt, distributed with
+# this software.
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+# ------------------------------------------------------------------
+
+from PyInstaller.utils.hooks import collect_data_files, collect_submodules
+
+# Collect timezone data files
+datas = collect_data_files("tzdata")
+
+# Collect submodules; each data subdirectory is in fact a package
+# (e.g., zoneinfo.Europe), so we need its __init__.py for data files
+# (e.g., zoneinfo/Europe/Ljubljana) to be discoverable via
+# importlib.resources
+hiddenimports = collect_submodules("tzdata")

src/_pyinstaller_hooks_contrib/tests/test_libraries.py

@@ -12,7 +12,7 @@
 import pytest
 from pathlib import Path
 from PyInstaller.compat import is_darwin, is_linux, is_py39, is_win
-from PyInstaller.utils.hooks import is_module_satisfies
+from PyInstaller.utils.hooks import is_module_satisfies, can_import_module
 from PyInstaller.utils.tests import importorskip, requires, xfail
 
 
@@ -886,3 +886,30 @@ def test_pypeteer(pyi_builder):
         import pypeteer
         print(pypeteer.version)
         """)
+
+
+@importorskip("tzdata")
+@pytest.mark.skipif(not is_py39 and not can_import_module('importlib_resources'),
+                    reason='importlib_resources is required on python < 3.9.')
+def test_tzdata(pyi_builder):
+    pyi_builder.test_source("""
+        import tzdata.zoneinfo  # hiddenimport
+
+        try:
+            import importlib.resources as importlib_resources
+        except ImportError:
+            import importlib_resources
+
+        # This emulates time-zone data retrieval from tzdata, as peformed by
+        # zoneinfo / backports.zoneinfo
+        zone_name = "Europe/Ljubljana"
+
+        components = zone_name.split("/")
+        package_name = ".".join(["tzdata.zoneinfo"] + components[:-1])
+        resource_name = components[-1]
+
+        with importlib_resources.open_binary(package_name, resource_name) as fp:
+            data = fp.read()
+
+        print(data)
+        """)