view tests/test-topic-rebase.t @ 3846:f9dad99a90d5

evolve: create a new commit instead of amending one of the divergents

This patch changes the behavior of evolve command while resolving
content-divergence to create a new commit instead of amending one of the
divergent ones.

In past, I have made this change, backed out this change and now today again I
am doing this change, so let's dive in some history.

Using cmdrewrite.amend() was never a good option as that requires hack to delete
the evolvestate and also gives us less control over things. We can't make the
commit on top of different parents as that of content-divergent ones. Due to all
these, I first made this change to create a new commit instead of amending one.

But, after few days, there was flakiness observed in the tests and turned out
that we need to do some dirstate dance as repo.dirstate.setparents() does not
always fix the dirstate. That flakiness was a blocker for progress at that time
and we decided to switch to amend back so that we can have things working with
some hacks and we can later fix the implementation part.

Now, yesterday while tackling resolving content-divergence of a stack which is
as follows:

C1 C2
 | |
B1 B2
 | |
A1 A2
 \/
base

where, A1-A2, B1-B2, C1-C2 are content-divergent with each other. Now we can
resolve A1-A2 very well because they have the same parent and let's say that
resolution leads to A3.
Now, we want to resolve B1-B2 and make the new resolution commit on top of A3 so
that we can end up something like:

C3
 |
B3
 |
A3
 |
base

however, amending one of the divergent changesets, it's not possible to create a
commit on a different parent like A3 here without some relocation. We should
prevent relocation as that may leads to some conflicts and should change the
parent before committing.

So, looking ahead, we can't move with using amend as still using that we will
need some relocation hacks making code ugly and prone to bad behaviors, bugs.
Let's change back to creating a new commit so that we can move forward in a good
way.

About repo.dirstate.setparents() not setting the dirstate, I have researched
yesterday night about how we can do that and found out that we can use
cmdrewrite._uncommitdirstate() here. Expect upcoming patches to improve the
documentation of that function.

There are lot of test changes because of change in hash but there is no behavior
change. The only behavior change is in test-evolve-abort-contentdiv.t which is
nice because creating a new commit helps us in stripping that while aborting.
We have a lot of testing of content-divergence and no behavior change gives
enough confidence for making this change.

I reviewed the patch carefully to make sure there is no behavior change and I
suggest reviewer to do the same.

test of the rebase command
--------------------------

  $ cat >> $HGRCPATH <<EOF
  > [defaults]
  > amend=-d "0 0"
  > fold=-d "0 0"
  > split=-d "0 0"
  > amend=-d "0 0"
  > [web]
  > push_ssl = false
  > allow_push = *
  > [phases]
  > publish = False
  > [diff]
  > git = 1
  > unified = 0
  > [ui]
  > interactive = true
  > [extensions]
  > rebase=
  > EOF
  $ echo "evolve=$(echo $(dirname $TESTDIR))/hgext3rd/evolve/" >> $HGRCPATH
  $ echo "topic=$(echo $(dirname $TESTDIR))/hgext3rd/topic/" >> $HGRCPATH
  $ mkcommit() {
  >    echo "$1" > "$1"
  >    hg add "$1"
  >    hg ci -m "add $1" $2 $3
  > }
  $ logtopic() {
  >    hg log -G -T "{rev}:{node}\ntopics: {topic}" 
  > }

Check that rebase keep the topic in the simple case (1 changeset, no merge conflict)
------------------------------------------------------------------------------------

  $ hg init testrebase
  $ cd testrebase
  $ mkcommit ROOT

Work on myfeature
  $ hg topic myfeature
  marked working directory as topic: myfeature
  $ mkcommit feature1
  active topic 'myfeature' grew its first changeset
  (see 'hg help topics' for more information)
  $ hg stack
  ### topic: myfeature
  ### target: default (branch)
  t1@ add feature1 (current)
  t0^ add ROOT (base)
  $ logtopic
  @  1:39e7a938055e87615edf675c24a10997ff05bb06
  |  topics: myfeature
  o  0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
     topics:

Create another commit on default
  $ hg update --rev default
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit default
  $ logtopic
  @  2:be7622a7a0f43ba713e152f56441275f8e8711ef
  |  topics:
  | o  1:39e7a938055e87615edf675c24a10997ff05bb06
  |/   topics: myfeature
  o  0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
     topics:

Rebase the commit
  $ hg update --rev 1
  switching to topic myfeature
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg rebase
  rebasing 1:39e7a938055e "add feature1" (myfeature)
  switching to topic myfeature
  $ hg stack
  ### topic: myfeature
  ### target: default (branch)
  t1@ add feature1 (current)
  t0^ add default (base)
  $ logtopic
  @  3:fc6593661cf3256ba165cbccd6019ead17cc3726
  |  topics: myfeature
  o  2:be7622a7a0f43ba713e152f56441275f8e8711ef
  |  topics:
  o  0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
     topics:
  $ hg up 3
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg stack
  ### topic: myfeature
  ### target: default (branch)
  t1@ add feature1 (current)
  t0^ add default (base)

Check that rebase keep the topic in case of merge conflict
----------------------------------------------------------

Create a common base
  $ hg topic --clear
  $ echo "A" > file
  $ hg commit -A -m "default2" file
  created new head
  (consider using topic for lightweight branches. See 'hg help topic')

Update the common file in a topic
  $ hg topic myotherfeature
  marked working directory as topic: myotherfeature
  $ echo "B" >> file
  $ hg commit -m "myotherfeature1"
  active topic 'myotherfeature' grew its first changeset
  (see 'hg help topics' for more information)

Update the common file in default
  $ hg update --rev default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "A2" > file
  $ hg commit -m "default3"

Rebase the topic
  $ hg update --rev 5
  switching to topic myotherfeature
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg rebase
  rebasing 5:81f854012ec5 "myotherfeature1" (myotherfeature)
  merging file
  warning: conflicts while merging file! (edit, then use 'hg resolve --mark')
  switching to topic myotherfeature
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Resolve the conflict
  $ echo A2 > file
  $ echo B >> file
  $ hg resolve -m
  (no more unresolved files)
  continue: hg rebase --continue
  $ hg rebase --continue
  rebasing 5:81f854012ec5 "myotherfeature1" (myotherfeature)

Check the the commit has the right topic

  $ logtopic
  @  7:6ccb9ec4913b64f3ad719ff1ba66495a70bf35a4
  |  topics: myotherfeature
  o  6:0b124ef641a7a6f4715d962650d3b367e8c800be
  |  topics:
  o  4:0cd2e1a45ac4e3f9603a05ccfa6d1c70cd759bc5
  |  topics:
  o  3:fc6593661cf3256ba165cbccd6019ead17cc3726
  |  topics: myfeature
  o  2:be7622a7a0f43ba713e152f56441275f8e8711ef
  |  topics:
  o  0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
     topics:
  $ hg stack
  ### topic: myotherfeature
  ### target: default (branch)
  t1@ myotherfeature1 (current)
  t0^ default3 (base)
  $ hg update --rev 7
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg stack
  ### topic: myotherfeature
  ### target: default (branch)
  t1@ myotherfeature1 (current)
  t0^ default3 (base)