Incorrect age calculation for future dates

pendulum/date.py

@@ -80,7 +80,7 @@ def week_of_month(self):
 
     @property
     def age(self):
-        return self.diff().in_years()
+        return self.diff(abs=False).in_years()
 
     @property
     def quarter(self):

pendulum/datetime.py

@@ -193,7 +193,7 @@ def timezone_name(self):  # type: () -> Union[str, None]
 
     @property
     def age(self):
-        return self.date().diff(self.now(self.tz).date()).in_years()
+        return self.date().diff(self.now(self.tz).date(), abs=False).in_years()
 
     def is_local(self):
         return self.offset == self.in_timezone(pendulum.local_timezone()).offset

tests/date/test_getters.py

@@ -36,7 +36,8 @@ def test_days_in_month():
 def test_age():
     d = pendulum.Date.today()
     assert d.age == 0
-    assert d.add(years=1).age == 1
+    assert d.add(years=1).age == -1
+    assert d.subtract(years=1).age == 1
 
 
 def test_is_leap_year():

tests/datetime/test_getters.py

@@ -94,7 +94,8 @@ def test_int_timestamp_accuracy():
 def test_age():
     d = pendulum.now()
     assert d.age == 0
-    assert d.add(years=1).age == 1
+    assert d.add(years=1).age == -1
+    assert d.subtract(years=1).age == 1
 
 
 def test_local():