.

wcfs/δbtail_test.go

@@ -1402,6 +1402,17 @@ func TestΔBTail(t *testing.T) {
 			  7:  K(1,2,3,4,5,6,7),
 			  oo: K(1,2,3,4,5,6,7,oo)}),
 
+		// reflow of keys for rebuild: even if tracked={1}, changes to all A/B/C nodes
+		// need to be rescanned. Contrary to the above case the reflow is not detected
+		// at separate diff(A,B) and diff(B,C) runs.
+		"T3,5,7/B1:a,2:b-B3:c,4:d-B5:e,6:f-B7:g,8:h",
+		"T/B1:b",
+		"T2,4,6/B1:a-B2:b,3:c-B4:d,5:e-B6:f,7:g",
+		// similar situation where rebuild has to detect reflow in between non-neighbour trees
+		"T3,6/B1:a,2:b-B3:c,4:d-B6:f,7:g",
+		"T4,7/B1:b-B4:d,5:e-B7:g,8:h",
+		"T2,5,8/B1:a-B2:b,3:c-B5:e,6:f-B8:h,9:i",
+
 		// depth=2; bucket split; +3 in new bucket; left T remain
 		// _unchanged_ even though B under it is modified; right arm is
 		// added to tracking set because 2 migrates there.