Merge pull request #22 from dh-tech/20-four-digit-years

Ensure years are always 4 digits

tests/test_dateformat/test_iso8601.py

@@ -25,3 +25,9 @@ def test_parse_range(self):
         assert ISO8601DateFormat().parse("1800/1900") == UndateInterval(
             Undate(1800), Undate(1900)
         )
+
+    def test_to_string(self):
+        # NOTE: iso8601 to_string currently tested more thoroughly
+        # in undate str tests; may want to move those tests here
+        assert ISO8601DateFormat().to_string(Undate(900)) == "0900"
+        assert ISO8601DateFormat().to_string(Undate(33)) == "0033"

tests/test_undate.py

@@ -44,7 +44,7 @@ def test_str(self):
 
     def test_str_open_range(self):
         # 900 -
-        assert str(UndateInterval(Undate(900))) == "900/"
+        assert str(UndateInterval(Undate(900))) == "0900/"
         # - 1900
         assert str(UndateInterval(latest=Undate(1900))) == "../1900"
         # - 1900-12

undate/dateformat/iso8601.py

@@ -51,9 +51,15 @@ def to_string(self, undate: Undate) -> str:
         # then combine
         for date_portion, known in undate.known_values.items():
             if known:
-                date_parts.append(
-                    undate.earliest.strftime(self.iso_format[date_portion])
-                )
+                # NOTE: datetime strftime for %Y for 3-digit year
+                # results in leading zero in some environments
+                # and not others; force year to always be 4 digits
+                if date_portion == "year":
+                    date_parts.append("%04d" % undate.earliest.year)
+                else:
+                    date_parts.append(
+                        undate.earliest.strftime(self.iso_format[date_portion])
+                    )
             elif date_portion == "year":
                 # if not known but this is year, add '-' for --MM-DD unknown year format
                 date_parts.append("-")