ColTypeDate: format "countdown" as described in example text

The "countdown" format has been the same as the "relative" format, except
that negative durations are not rendered, for about a decade. (There was
a minor fix in #1840.)

However, the example text shows something that looks like 00:00:00. This
is how "countdown" was originally rendered but this was changed as part of
the "isodate" branch in 995de68. See
#4013 for more
information.

Fixes #4013

Author: apoelstra

src/columns/ColTypeDate.cpp

@@ -75,7 +75,7 @@ void ColumnTypeDate::measure(Task& task, unsigned int& minimum, unsigned int& ma
       minimum = maximum = Datetime::length(format);
     } else if (_style == "countdown") {
       Datetime now;
-      minimum = maximum = Duration(date - now).formatVague(true).length();
+      if (date > now) minimum = maximum = Duration(date - now).format().length();
     } else if (_style == "julian") {
       minimum = maximum = format(date.toJulian(), 13, 12).length();
     } else if (_style == "epoch") {
@@ -120,7 +120,7 @@ void ColumnTypeDate::render(std::vector<std::string>& lines, Task& task, int wid
       renderStringLeft(lines, width, color, date.toString(format));
     } else if (_style == "countdown") {
       Datetime now;
-      renderStringRight(lines, width, color, Duration(date - now).formatVague(true));
+      if (date > now) renderStringRight(lines, width, color, Duration(date - now).format());
     } else if (_style == "julian")
       renderStringRight(lines, width, color, format(date.toJulian(), 13, 12));
 

test/columns.test.py

@@ -417,7 +417,7 @@ def test_date_format_countdown(self):
         """Verify due.countdown formatting"""
         code, out, err = self.t("xxx rc.report.xxx.columns:id,due.countdown")
         self.assertRegex(out, r"1\s+")
-        self.assertRegex(out, r"2\s+[0-9.]+[hmin]+")
+        self.assertRegex(out, r"2\s+(\d+d )?\d+:\d{2}:\d{2}")
 
     def test_date_format_unrecognized(self):
         """Verify due.donkey formatting fails"""