Convert no-roots-from-old-gens into yarn

2 files changed, 25 insertions, 0 deletions

diff --git a/yarns/0030-basics.yarn b/yarns/0030-basics.yarn
index 5d563f0b..92304a50 100644
--- a/yarns/0030-basics.yarn
+++ b/yarns/0030-basics.yarn
@@ -136,3 +136,18 @@ directory `L`.
     WHEN user U backs up directory L to repository R
     AND user U restores their latest generation in repository R into X
     THEN L, restored to X, matches manifest M
+
+Changing backup roots
+---------------------
+
+When we change the backup roots, i.e., the directories we want backed
+up, we do not want the any dropped backup roots to be included in the
+new backup.
+
+    SCENARIO replace backup root with new one
+    GIVEN 1k of new data in directory L1
+    AND 1k of new data in directory L2
+    WHEN user U backs up directory L1 to repository R
+    AND user U backs up directory L2 to repository R
+    AND user U lists latest generation in repository R into F
+    THEN nothing in F matches L1
diff --git a/yarns/9000-implements.yarn b/yarns/9000-implements.yarn
index f70ccd07..aeb253d1 100644
--- a/yarns/9000-implements.yarn
+++ b/yarns/9000-implements.yarn
@@ -352,6 +352,16 @@ Do all lines match?
     IMPLEMENTS THEN all lines in (\S+) match (\S+)
     ! grep -E -v -e "$MATCH_2" -- "$DATADIR/$MATCH_1"
 
+Does no line match?
+
+    IMPLEMENTS THEN nothing in (\S+) matches (\S+)
+    if grep -E -e "$MATCH_2" -- "$DATADIR/$MATCH_1" | grep '.*'
+    then
+        echo "At least one line matches, when none may!" 1>&2
+        exit 1
+    fi
+
+
 Check on user group membership
 ------------------------------