--- /dev/null
+# This may have been leftover from a previous run, when switching
+# between "real" redo and minimal/do, so clean it up.
+rm -f touch1
+
+# simply create touch1
+echo 'echo hello' >touch1.do
+redo touch1
+[ -e touch1 ] || exit 55
+[ "$(cat touch1)" = "hello" ] || exit 56
+
+# ensure that 'redo touch1' always re-runs touch1.do even if we have
+# already built touch1 in this session, and even if touch1 already exists.
+echo 'echo hello2' >touch1.do
+redo touch1
+[ "$(cat touch1)" = "hello2" ] || exit 57
+
+# ensure that touch1 is rebuilt even if it got deleted after the last redo
+# inside the same session. Also ensure that we can produce a zero-byte
+# output file explicitly.
+rm -f touch1
+echo 'touch $3' >touch1.do
+redo touch1
+[ -e touch1 ] || exit 66
+[ -z "$(cat touch1)" ] || exit 67
+
+# Also test that zero bytes of output does not create the file at all, as
+# opposed to creating a zero-byte file.
+rm -f touch1
+echo 'touch touch1-ran' >touch1.do
+redo touch1
+[ -e touch1 ] && exit 75
+[ -e touch1-ran ] || exit 76
+rm -f touch1-ran
+
+# Make sure that redo-ifchange *won't* rebuild touch1 if we have already
+# built it, even if building it did not produce an output file.
+redo-ifchange touch1
+[ -e touch1 ] && exit 77
+[ -e touch1-ran ] && exit 78
+
+rm -f touch1.do