tests/test-absorb.t

internals: document CBOR utilization

I spoke with some people at Mozilla about CBOR and they advised me
that we should be careful about the subset of CBOR we use in order
to mitigate security, performance, and compatibility concerns.

This commit establishes a document that attempts to formalize our
use of CBOR.

Its main limitations are on what types are allowed. It explicitly
enumerates which types are supported. Notable missing features
include:

* Indefinite-length arrays and maps
* Text strings (bytes all the way)
* Floats
* Date/time types
* Big integers
* Use of indefinite-length byte strings for map keys, values in
  containers.

If we have a need for any of these, we can have a discussion about
them when the time comes.

Differential Revision: https://phab.mercurial-scm.org/D4412

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > absorb=
  > EOF

  $ sedi() { # workaround check-code
  > pattern="$1"
  > shift
  > for i in "$@"; do
  >     sed "$pattern" "$i" > "$i".tmp
  >     mv "$i".tmp "$i"
  > done
  > }

  $ hg init repo1
  $ cd repo1

Do not crash with empty repo:

  $ hg absorb
  abort: no changeset to change
  [255]

Make some commits:

  $ for i in 1 2 3 4 5; do
  >   echo $i >> a
  >   hg commit -A a -m "commit $i" -q
  > done

  $ hg annotate a
  0: 1
  1: 2
  2: 3
  3: 4
  4: 5

Change a few lines:

  $ cat > a <<EOF
  > 1a
  > 2b
  > 3
  > 4d
  > 5e
  > EOF

Preview absorb changes:

  $ hg absorb --print-changes --dry-run
  showing changes for a
          @@ -0,2 +0,2 @@
  4ec16f8 -1
  5c5f952 -2
  4ec16f8 +1a
  5c5f952 +2b
          @@ -3,2 +3,2 @@
  ad8b8b7 -4
  4f55fa6 -5
  ad8b8b7 +4d
  4f55fa6 +5e

Run absorb:

  $ hg absorb
  saved backup bundle to * (glob)
  2 of 2 chunk(s) applied
  $ hg annotate a
  0: 1a
  1: 2b
  2: 3
  3: 4d
  4: 5e

Delete a few lines and related commits will be removed if they will be empty:

  $ cat > a <<EOF
  > 2b
  > 4d
  > EOF
  $ hg absorb
  saved backup bundle to * (glob)
  3 of 3 chunk(s) applied
  $ hg annotate a
  1: 2b
  2: 4d
  $ hg log -T '{rev} {desc}\n' -Gp
  @  2 commit 4
  |  diff -r 1cae118c7ed8 -r 58a62bade1c6 a
  |  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  |  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  |  @@ -1,1 +1,2 @@
  |   2b
  |  +4d
  |
  o  1 commit 2
  |  diff -r 84add69aeac0 -r 1cae118c7ed8 a
  |  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  |  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  |  @@ -0,0 +1,1 @@
  |  +2b
  |
  o  0 commit 1
  

Non 1:1 map changes will be ignored:

  $ echo 1 > a
  $ hg absorb
  nothing applied
  [1]

Insertaions:

  $ cat > a << EOF
  > insert before 2b
  > 2b
  > 4d
  > insert aftert 4d
  > EOF
  $ hg absorb -q
  $ hg status
  $ hg annotate a
  1: insert before 2b
  1: 2b
  2: 4d
  2: insert aftert 4d

Bookmarks are moved:

  $ hg bookmark -r 1 b1
  $ hg bookmark -r 2 b2
  $ hg bookmark ba
  $ hg bookmarks
     b1                        1:b35060a57a50
     b2                        2:946e4bc87915
   * ba                        2:946e4bc87915
  $ sedi 's/insert/INSERT/' a
  $ hg absorb -q
  $ hg status
  $ hg bookmarks
     b1                        1:a4183e9b3d31
     b2                        2:c9b20c925790
   * ba                        2:c9b20c925790

Non-mofified files are ignored:

  $ touch b
  $ hg commit -A b -m b
  $ touch c
  $ hg add c
  $ hg rm b
  $ hg absorb
  nothing applied
  [1]
  $ sedi 's/INSERT/Insert/' a
  $ hg absorb
  saved backup bundle to * (glob)
  2 of 2 chunk(s) applied
  $ hg status
  A c
  R b

Public commits will not be changed:

  $ hg phase -p 1
  $ sedi 's/Insert/insert/' a
  $ hg absorb -pn
  showing changes for a
          @@ -0,1 +0,1 @@
          -Insert before 2b
          +insert before 2b
          @@ -3,1 +3,1 @@
  85b4e0e -Insert aftert 4d
  85b4e0e +insert aftert 4d
  $ hg absorb
  saved backup bundle to * (glob)
  1 of 2 chunk(s) applied
  $ hg diff -U 0
  diff -r 1c8eadede62a a
  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	* (glob)
  @@ -1,1 +1,1 @@
  -Insert before 2b
  +insert before 2b
  $ hg annotate a
  1: Insert before 2b
  1: 2b
  2: 4d
  2: insert aftert 4d

Make working copy clean:

  $ hg revert -q -C a b
  $ hg forget c
  $ rm c
  $ hg status

Merge commit will not be changed:

  $ echo 1 > m1
  $ hg commit -A m1 -m m1
  $ hg bookmark -q -i m1
  $ hg update -q '.^'
  $ echo 2 > m2
  $ hg commit -q -A m2 -m m2
  $ hg merge -q m1
  $ hg commit -m merge
  $ hg bookmark -d m1
  $ hg log -G -T '{rev} {desc} {phase}\n'
  @    6 merge draft
  |\
  | o  5 m2 draft
  | |
  o |  4 m1 draft
  |/
  o  3 b draft
  |
  o  2 commit 4 draft
  |
  o  1 commit 2 public
  |
  o  0 commit 1 public
  
  $ echo 2 >> m1
  $ echo 2 >> m2
  $ hg absorb
  abort: no changeset to change
  [255]
  $ hg revert -q -C m1 m2

Use a new repo:

  $ cd ..
  $ hg init repo2
  $ cd repo2

Make some commits to multiple files:

  $ for f in a b; do
  >   for i in 1 2; do
  >     echo $f line $i >> $f
  >     hg commit -A $f -m "commit $f $i" -q
  >   done
  > done

Use pattern to select files to be fixed up:

  $ sedi 's/line/Line/' a b
  $ hg status
  M a
  M b
  $ hg absorb a
  saved backup bundle to * (glob)
  1 of 1 chunk(s) applied
  $ hg status
  M b
  $ hg absorb --exclude b
  nothing applied
  [1]
  $ hg absorb b
  saved backup bundle to * (glob)
  1 of 1 chunk(s) applied
  $ hg status
  $ cat a b
  a Line 1
  a Line 2
  b Line 1
  b Line 2

Test config option absorb.max-stack-size:

  $ sedi 's/Line/line/' a b
  $ hg log -T '{rev}:{node} {desc}\n'
  3:712d16a8f445834e36145408eabc1d29df05ec09 commit b 2
  2:74cfa6294160149d60adbf7582b99ce37a4597ec commit b 1
  1:28f10dcf96158f84985358a2e5d5b3505ca69c22 commit a 2
  0:f9a81da8dc53380ed91902e5b82c1b36255a4bd0 commit a 1
  $ hg --config absorb.max-stack-size=1 absorb -pn
  absorb: only the recent 1 changesets will be analysed
  showing changes for a
          @@ -0,2 +0,2 @@
          -a Line 1
          -a Line 2
          +a line 1
          +a line 2
  showing changes for b
          @@ -0,2 +0,2 @@
          -b Line 1
  712d16a -b Line 2
          +b line 1
  712d16a +b line 2

Test obsolete markers creation:

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > evolution=createmarkers
  > [absorb]
  > add-noise=1
  > EOF

  $ hg --config absorb.max-stack-size=3 absorb
  absorb: only the recent 3 changesets will be analysed
  2 of 2 chunk(s) applied
  $ hg log -T '{rev}:{node|short} {desc} {get(extras, "absorb_source")}\n'
  6:3dfde4199b46 commit b 2 712d16a8f445834e36145408eabc1d29df05ec09
  5:99cfab7da5ff commit b 1 74cfa6294160149d60adbf7582b99ce37a4597ec
  4:fec2b3bd9e08 commit a 2 28f10dcf96158f84985358a2e5d5b3505ca69c22
  0:f9a81da8dc53 commit a 1 
  $ hg absorb
  1 of 1 chunk(s) applied
  $ hg log -T '{rev}:{node|short} {desc} {get(extras, "absorb_source")}\n'
  10:e1c8c1e030a4 commit b 2 3dfde4199b4610ea6e3c6fa9f5bdad8939d69524
  9:816c30955758 commit b 1 99cfab7da5ffdaf3b9fc6643b14333e194d87f46
  8:5867d584106b commit a 2 fec2b3bd9e0834b7cb6a564348a0058171aed811
  7:8c76602baf10 commit a 1 f9a81da8dc53380ed91902e5b82c1b36255a4bd0

Executable files:

  $ cat >> $HGRCPATH << EOF
  > [diff]
  > git=True
  > EOF
  $ cd ..
  $ hg init repo3
  $ cd repo3

#if execbit
  $ echo > foo.py
  $ chmod +x foo.py
  $ hg add foo.py
  $ hg commit -mfoo
#else
  $ hg import -q --bypass - <<EOF
  > # HG changeset patch
  > foo
  > 
  > diff --git a/foo.py b/foo.py
  > new file mode 100755
  > --- /dev/null
  > +++ b/foo.py
  > @@ -0,0 +1,1 @@
  > +
  > EOF
  $ hg up -q
#endif

  $ echo bla > foo.py
  $ hg absorb --dry-run --print-changes
  showing changes for foo.py
          @@ -0,1 +0,1 @@
  99b4ae7 -
  99b4ae7 +bla
  $ hg absorb
  1 of 1 chunk(s) applied
  $ hg diff -c .
  diff --git a/foo.py b/foo.py
  new file mode 100755
  --- /dev/null
  +++ b/foo.py
  @@ -0,0 +1,1 @@
  +bla
  $ hg diff

Remove lines may delete changesets:

  $ cd ..
  $ hg init repo4
  $ cd repo4
  $ cat > a <<EOF
  > 1
  > 2
  > EOF
  $ hg commit -m a12 -A a
  $ cat > b <<EOF
  > 1
  > 2
  > EOF
  $ hg commit -m b12 -A b
  $ echo 3 >> b
  $ hg commit -m b3
  $ echo 4 >> b
  $ hg commit -m b4
  $ echo 1 > b
  $ echo 3 >> a
  $ hg absorb -pn
  showing changes for a
          @@ -2,0 +2,1 @@
  bfafb49 +3
  showing changes for b
          @@ -1,3 +1,0 @@
  1154859 -2
  30970db -3
  a393a58 -4
  $ hg absorb -v | grep became
  bfafb49242db: 1 file(s) changed, became 1a2de97fc652
  115485984805: 2 file(s) changed, became 0c930dfab74c
  30970dbf7b40: became empty and was dropped
  a393a58b9a85: became empty and was dropped
  $ hg log -T '{rev} {desc}\n' -Gp
  @  5 b12
  |  diff --git a/b b/b
  |  new file mode 100644
  |  --- /dev/null
  |  +++ b/b
  |  @@ -0,0 +1,1 @@
  |  +1
  |
  o  4 a12
     diff --git a/a b/a
     new file mode 100644
     --- /dev/null
     +++ b/a
     @@ -0,0 +1,3 @@
     +1
     +2
     +3
  

Use revert to make the current change and its parent disappear.
This should move us to the non-obsolete ancestor.

  $ cd ..
  $ hg init repo5
  $ cd repo5
  $ cat > a <<EOF
  > 1
  > 2
  > EOF
  $ hg commit -m a12 -A a
  $ hg id
  bfafb49242db tip
  $ echo 3 >> a
  $ hg commit -m a123 a
  $ echo 4 >> a
  $ hg commit -m a1234 a
  $ hg id
  82dbe7fd19f0 tip
  $ hg revert -r 0 a
  $ hg absorb -pn
  showing changes for a
          @@ -2,2 +2,0 @@
  f1c23dd -3
  82dbe7f -4
  $ hg absorb --verbose
  f1c23dd5d08d: became empty and was dropped
  82dbe7fd19f0: became empty and was dropped
  a: 1 of 1 chunk(s) applied
  $ hg id
  bfafb49242db tip