+### attr_duration_minutes
+
+# Wenn das Attribut undef ist:
+is(new_item->inty, undef, 'uninitialized: raw');
+is(new_item->inty_as_hours, 0, 'uninitialized: as_hours');
+is(new_item->inty_as_minutes, 0, 'uninitialized: as_minutes');
+is(new_item->inty_as_duration_string, undef, 'uninitialized: as_duration_string');
+
+# Auslesen kleiner 60 Minuten:
+is(new_item(inty => 37)->inty, 37, 'initialized < 60: raw');
+is(new_item(inty => 37)->inty_as_hours, 0, 'initialized < 60: as_hours');
+is(new_item(inty => 37)->inty_as_minutes, 37, 'initialized < 60: as_minutes');
+is(new_item(inty => 37)->inty_as_duration_string, '0:37', 'initialized < 60: as_duration_string');
+
+# Auslesen größer 60 Minuten:
+is(new_item(inty => 145)->inty, 145, 'initialized > 60: raw');
+is(new_item(inty => 145)->inty_as_hours, 2, 'initialized > 60: as_hours');
+is(new_item(inty => 145)->inty_as_minutes, 25, 'initialized > 60: as_minutes');
+is(new_item(inty => 145)->inty_as_duration_string, '2:25', 'initialized > 60: as_duration_string');
+
+$item = new_item(inty => 145); $item->inty_as_duration_string(undef);
+is($item->inty, undef, 'write as_duration_string undef read raw');
+is($item->inty_as_minutes, 0, 'write as_duration_string undef read as_minutes');
+is($item->inty_as_hours, 0, 'write as_duration_string undef read as_hours');
+is($item->inty_as_duration_string, undef, 'write as_duration_string undef read as_duration_string');
+
+$item = new_item(inty => 145); $item->inty_as_duration_string('');
+is($item->inty, undef, 'write as_duration_string "" read raw');
+is($item->inty_as_minutes, 0, 'write as_duration_string "" read as_minutes');
+is($item->inty_as_hours, 0, 'write as_duration_string "" read as_hours');
+is($item->inty_as_duration_string, undef, 'write as_duration_string "" read as_duration_string');
+
+$item = new_item(inty => 145); $item->inty_as_duration_string("3:21");
+is($item->inty, 201, 'write as_duration_string 3:21 read raw');
+is($item->inty_as_minutes, 21, 'write as_duration_string 3:21 read as_minutes');
+is($item->inty_as_hours, 3, 'write as_duration_string 3:21 read as_hours');
+is($item->inty_as_duration_string, "3:21", 'write as_duration_string 3:21 read as_duration_string');
+
+$item = new_item(inty => 145); $item->inty_as_duration_string("03:1");
+is($item->inty, 181, 'write as_duration_string 03:1 read raw');
+is($item->inty_as_minutes, 1, 'write as_duration_string 03:1 read as_minutes');
+is($item->inty_as_hours, 3, 'write as_duration_string 03:1 read as_hours');
+is($item->inty_as_duration_string, "3:01", 'write as_duration_string 03:1 read as_duration_string');
+
+# Parametervalidierung
+throws_ok { new_item()->inty_as_duration_string('invalid') } qr/invalid.*format/i, 'invalid duration format';
+