Re-enable correctly py27 testing and document it

rel #93.

.github/workflows/cicd.yml

@@ -1,9 +1,27 @@
 name: croniter
 on: [workflow_dispatch, push, pull_request]
 jobs:
-  build:
+  build-py2:
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["2.7"]
+    steps:
+    - uses: actions/checkout@v3
+    - name: install dependencies && test on py27
+      run: |
+        set -ex
+        sudo apt update && sudo apt install -y python2.7
+        # install py 2 with eg: apt install python2.7
+        mkdir venv2 && curl -sSL "https://github.com/pypa/get-virtualenv/blob/20.27.0/public/2.7/virtualenv.pyz?raw=true" > venv2/venv && python2.7 venv2/venv venv2
+        venv2/bin/python2 -m pip install -r ./requirements/test.txt
+        venv2/bin/tox --direct -e "py${pyver//\.}-{std,coverage}"
+
+  build-py3:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
       matrix:
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
     steps:
@@ -12,15 +30,11 @@ jobs:
       uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
+    - name: install dependencies && test on py3
       run: |
         set -ex
         python -m pip install --upgrade --use-pep517 pip
         pip install --use-pep517 -r requirements/test.txt
-    - name: Test with pytest
-      run: |
-           pyver=$(python --version 2>&1 | awk '{print substr($2, 0, 4)}' | awk '{ sub(/[ \t]+$/, ""); print }');
-           case $pyver in
-             2.7) tox -e "py${pyver//\.}-{std,coverage}";;
-             *) tox -e "py${pyver//\.}-std";;
-           esac
+        pyver=$(python --version 2>&1 | awk '{print substr($2, 0, 4)}' | awk '{ sub(/[ \t]+$/, ""); print }')
+        tox --direct -e "py${pyver//\.}-{std,coverage}"
+

CHANGELOG.rst

@@ -5,6 +5,7 @@ Changelog
 ------------------
 
 - Fix overflow on 32bits systems (#87) [kiorky]
+- Fix python2 testing (related to #93) [kiorky]
 
 3.0.3 (2024-07-26)
 ------------------

README.rst

@@ -325,6 +325,20 @@ Develop this package
     py.test src
 
 
+Testing under py2
+==================
+
+Install prerequisisites ::
+
+    # install py 2 with eg: apt install python2.7
+    mkdir venv2 && curl -sSL "https://github.com/pypa/get-virtualenv/blob/20.27.0/public/2.7/virtualenv.pyz?raw=true" > venv2/venv && python2 venv2/venv venv2
+    venv2/bin/python2 -m pip install -r ./requirements/test.txt
+
+Run tests::
+
+    ./venv2/bin/tox --direct -e py27-std
+
+
 Make a new release
 ====================
 We use zest.fullreleaser, a great release infrastructure.

requirements/test.txt

@@ -1,9 +1,12 @@
 -r base.txt
-pytz
 pytest>=3.0.3
 tox>=2.4.1
 coverage>=4.2
 mock>=2.0.0  # For Python 2
 coveralls
 flake8
 tzlocal
+pylint
+pylama
+tox-direct
+setuptools

src/croniter/croniter.py

@@ -121,6 +121,11 @@ def is_32bit():
 # retrocompat
 VALID_LEN_EXPRESSION = set([a for a in CRON_FIELDS if isinstance(a, int)])
 EXPRESSIONS = {}
+try:
+    # py3 recent
+    UTC_DT = datetime.timezone.utc
+except AttributeError:
+    UTC_DT = pytz.utc
 
 
 def timedelta_to_seconds(td):
@@ -1010,7 +1015,7 @@ def expand(cls, expr_format, hash_id=None, second_at_beginning=False, from_times
 
     @classmethod
     def _get_low_from_current_date_number(cls, i, step, from_timestamp):
-        dt = datetime.datetime.fromtimestamp(from_timestamp, tz=datetime.timezone.utc)
+        dt = datetime.datetime.fromtimestamp(from_timestamp, tz=UTC_DT)
         if i == MINUTE_FIELD:
             return dt.minute % step
         if i == HOUR_FIELD: