--- a/tests/test-setdiscovery.t	Tue Feb 02 13:25:28 2021 -0500
+++ b/tests/test-setdiscovery.t	Fri Jan 29 15:23:07 2021 +0100
@@ -1588,3 +1588,139 @@
       common:                    0
       missing:                   1
   common heads: 66f7d451a68b
+
+  $ cd ..
+
+
+Test debuging discovery using different subset of the same repository
+=====================================================================
+
+remote is a local subset
+------------------------
+
+remote will be last 25 heads of the local graph
+
+  $ cd $TESTTMP/manyheads
+  $ hg -R a debugdiscovery \
+  > --debug \
+  > --remote-as-revs 'last(heads(all()), 25)' \
+  > --config devel.discovery.randomize=false
+  query 1; heads
+  searching for changes
+  all remote heads known locally
+  elapsed time:  * seconds (glob)
+  round-trips:                   1
+  heads summary:
+    total common heads:         25
+      also local heads:         25
+      also remote heads:        25
+      both:                     25
+    local heads:               260
+      common:                   25
+      missing:                 235
+    remote heads:               25
+      common:                   25
+      unknown:                   0
+  local changesets:           1340
+    common:                    400
+      heads:                    25
+      roots:                     1
+    missing:                   940
+      heads:                   235
+      roots:                   235
+    first undecided set:       940
+      heads:                   235
+      roots:                   235
+      common:                    0
+      missing:                 940
+  common heads: 0dfd965d91c6 0fe09b60448d 14a17233ce9d 175c0a3072cf 1c51e2c80832 1e51600e0698 24eb5f9bdbab 25ce09526613 36bd00abde57 426989fdefa0 596d87362679 5dd1039ea5c0 5ef24f022278 5f230dc19419 80b39998accb 88f40688ffb5 9e37ddf8c632 abf4d55b075e b2ce801fddfe b368b6ac3ce3 c959bf2e869c c9fba6ba4e2e d783207cf649 d9a51e256f21 e3717a4e3753
+
+local is a local subset
+------------------------
+
+remote will be last 25 heads of the local graph
+
+  $ cd $TESTTMP/manyheads
+  $ hg -R a debugdiscovery b \
+  > --debug \
+  > --local-as-revs 'first(heads(all()), 25)' \
+  > --config devel.discovery.randomize=false
+  comparing with b
+  query 1; heads
+  searching for changes
+  taking quick initial sample
+  query 2; still undecided: 375, sample size is: 81
+  sampling from both directions
+  query 3; still undecided: 3, sample size is: 3
+  3 total queries *s (glob)
+  elapsed time:  * seconds (glob)
+  round-trips:                   3
+  heads summary:
+    total common heads:          1
+      also local heads:          0
+      also remote heads:         0
+      both:                      0
+    local heads:                25
+      common:                    0
+      missing:                  25
+    remote heads:                1
+      common:                    0
+      unknown:                   1
+  local changesets:            400
+    common:                    300
+      heads:                     1
+      roots:                     1
+    missing:                   100
+      heads:                    25
+      roots:                    25
+    first undecided set:       400
+      heads:                    25
+      roots:                     1
+      common:                  300
+      missing:                 100
+  common heads: 3ee37d65064a
+
+both local and remove are subset
+------------------------
+
+remote will be last 25 heads of the local graph
+
+  $ cd $TESTTMP/manyheads
+  $ hg -R a debugdiscovery \
+  > --debug \
+  > --local-as-revs 'first(heads(all()), 25)' \
+  > --remote-as-revs 'last(heads(all()), 25)' \
+  > --config devel.discovery.randomize=false
+  query 1; heads
+  searching for changes
+  taking quick initial sample
+  query 2; still undecided: 375, sample size is: 81
+  sampling from both directions
+  query 3; still undecided: 3, sample size is: 3
+  3 total queries in *s (glob)
+  elapsed time:  * seconds (glob)
+  round-trips:                   3
+  heads summary:
+    total common heads:          1
+      also local heads:          0
+      also remote heads:         0
+      both:                      0
+    local heads:                25
+      common:                    0
+      missing:                  25
+    remote heads:               25
+      common:                    0
+      unknown:                  25
+  local changesets:            400
+    common:                    300
+      heads:                     1
+      roots:                     1
+    missing:                   100
+      heads:                    25
+      roots:                    25
+    first undecided set:       400
+      heads:                    25
+      roots:                     1
+      common:                  300
+      missing:                 100
+  common heads: 3ee37d65064a