diff --git a/tests/test-exchange-obsmarkers-case-D4.t b/tests/test-exchange-obsmarkers-case-D4.t
new file mode 100644
--- /dev/null
+++ b/tests/test-exchange-obsmarkers-case-D4.t
@@ -0,0 +1,138 @@
+============================================
+Testing obsolescence markers push: Cases D.4
+============================================
+
+Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
+all changesets that requested to be "in sync" after the push (even if they are
+already on both side).
+
+This test belongs to a series of tests checking such set is properly computed
+and applied. This does not tests "obsmarkers" discovery capabilities.
+
+Category D: Partial Information Case
+TestCase 4: Unknown changeset in between known changesets
+
+D.4 Unknown changeset in between known one
+==========================================
+
+.. Mostly a clarification case
+..
+.. {{{
+..   B ø⇠◌⇠○ B''
+..     |   |
+..   A ø⇠◌⇠◔ A'
+..      \ /
+..       ● O
+..
+.. }}}
+..
+.. Should be treated as A.3 case:
+..
+.. {{{
+..
+..   B ø⇠○ B''
+..     | |
+..   A ø⇠◔ A'
+..     |/
+..     ● O
+..
+.. }}}
+
+Setup
+-----
+
+  $ . $TESTDIR/testlib/exchange-obsmarker-util.sh
+
+initial
+
+  $ setuprepos D.4
+  creating test repo for test case D.4
+  - pulldest
+  - main
+  - pushdest
+  cd into `main` and proceed with env setup
+  $ cd main
+  $ mkcommit A0
+  $ mkcommit B0
+  $ hg update -q 0
+  $ mkcommit A1
+  created new head
+  $ mkcommit B1
+  $ hg debugobsolete `getid 'desc(A0)'` aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+  $ hg debugobsolete aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa `getid 'desc(A1)'`
+  $ hg debugobsolete `getid 'desc(B0)'` bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+  $ hg debugobsolete bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb `getid 'desc(B1)'`
+  $ hg log -G --hidden
+  @  069b05c3876d (draft): B1
+  |
+  o  e5ea8f9c7314 (draft): A1
+  |
+  | x  6e72f0a95b5e (draft): B0
+  | |
+  | x  28b51eb45704 (draft): A0
+  |/
+  o  a9bdc8b26820 (public): O
+  
+  $ inspect_obsmarkers
+  obsstore content
+  ================
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  $ cd ..
+  $ cd ..
+
+Actual Test
+-----------
+
+  $ dotest D.4 A1
+  ## Running testcase D.4
+  # testing echange of "A1" (e5ea8f9c7314)
+  ## initial state
+  # obstore: main
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  # obstore: pushdest
+  # obstore: pulldest
+  ## pushing "A1" from main to pushdest
+  pushing to pushdest
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+  remote: 2 new obsolescence markers
+  ## post push state
+  # obstore: main
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  # obstore: pushdest
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  # obstore: pulldest
+  ## pulling "e5ea8f9c7314" from main into pulldest
+  pulling from main
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files
+  2 new obsolescence markers
+  (run 'hg update' to get a working copy)
+  ## post pull state
+  # obstore: main
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  # obstore: pushdest
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  # obstore: pulldest
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
+  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}