From 7a822a0fdf4b9a4643b3abe8ac75e2d9ffae0d67 Mon Sep 17 00:00:00 2001
From: "Dr. Tilmann Bubeck" <tilmann@bubecks.de>
Date: Mon, 3 Mar 2025 11:10:43 +0100
Subject: [PATCH] Improve TimeZoneFix with dunder methods

---
 Makefile                   |  2 +-
 aerofiles/util/__init__.py |  3 +++
 aerofiles/util/timezone.py | 25 ++++++++++++++++++++++++-
 tests/igc/test_timezone.py | 21 +++++++++++++++++++++
 4 files changed, 49 insertions(+), 2 deletions(-)
 create mode 100644 tests/igc/test_timezone.py

diff --git a/Makefile b/Makefile
index 3eb7935f..7b6b03a4 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 test: lint vermin pytest
 
 lint:
-	flake8 --exclude=".env,.git,docs" --ignore=E501,W504 .
+	flake8 --exclude=".env,.git,docs" --ignore=E501,W504 aerofiles tests
 
 vermin:
 	vermin aerofiles
diff --git a/aerofiles/util/__init__.py b/aerofiles/util/__init__.py
index e69de29b..82a9069f 100644
--- a/aerofiles/util/__init__.py
+++ b/aerofiles/util/__init__.py
@@ -0,0 +1,3 @@
+# flake8: noqa
+
+from .timezone import TimeZoneFix
diff --git a/aerofiles/util/timezone.py b/aerofiles/util/timezone.py
index 38d0dcf2..7136e9fd 100644
--- a/aerofiles/util/timezone.py
+++ b/aerofiles/util/timezone.py
@@ -2,10 +2,33 @@
 
 
 class TimeZoneFix(datetime.tzinfo):
+    """
+    A simple implementation of tzinfo to store timezone of IGC fixes.
 
-    def __init__(self, fix):
+    An alternative would be, to use "timezone" which is part of
+    Python since v3.2. However, because we try to be python 2.6+
+    compatible, we use this implementation. It can be replaced,
+    if we set Python 3.x as a minimum requirement for aerofiles.
+    """
+
+    def __init__(self, fix=0):
         self.fix = fix
 
+    def __eq__(self, other):
+        if isinstance(other, TimeZoneFix):
+            return self.fix == other.fix
+        return NotImplemented
+
+    def __hash__(self):
+        return hash(self.fix)
+
+    def __repr__(self):
+        """Convert to formal string, for repr().
+        """
+        return "%s.%s(%r)" % (self.__class__.__module__,
+                              self.__class__.__qualname__,
+                              self.fix)
+
     def utcoffset(self, dt):
         return datetime.timedelta(hours=self.fix)
 
diff --git a/tests/igc/test_timezone.py b/tests/igc/test_timezone.py
new file mode 100644
index 00000000..ed64ae8a
--- /dev/null
+++ b/tests/igc/test_timezone.py
@@ -0,0 +1,21 @@
+import copy
+
+from aerofiles.util import TimeZoneFix
+
+
+def test_not_equal():
+    tz1 = TimeZoneFix(1)
+    tz2 = TimeZoneFix(2)
+    assert (tz1 != tz2)
+
+
+def test_equal():
+    tz1 = TimeZoneFix(1)
+    tz2 = TimeZoneFix(1)
+    assert (tz1 == tz2)
+
+
+def test_deepcopy():
+    tz1 = TimeZoneFix(1)
+    tz2 = copy.deepcopy(tz1)
+    assert (tz1 == tz2)