$ echo "[extensions]" >> $HGRCPATH

  $ echo "extdiff=" >> $HGRCPATH

  $ hg init a

  $ cd a

  $ echo a > a

  $ echo b > b

  $ hg add

  adding a

  adding b

Should diff cloned directories:

  $ hg extdiff -o -r $opt

  Only in a: a

  Only in a: b

  [1]

  $ echo "[extdiff]" >> $HGRCPATH

  $ echo "cmd.falabala=echo" >> $HGRCPATH

  $ echo "opts.falabala=diffing" >> $HGRCPATH

  $ hg falabala

  diffing a.000000000000 a

  [1]

  $ hg help falabala

  hg falabala [OPTION]... [FILE]...

  use 'echo' to diff repository (or selected files)

      Show differences between revisions for the specified files, using the

      'echo' program.

      When two revision arguments are given, then changes are shown between

      those revisions. If only one revision is specified then that revision is

      compared to the working directory, and, when no revisions are specified,

      the working directory files are compared to its parent.

  options:

   -o --option OPT [+]       pass option to comparison program

   -r --rev REV [+]          revision

   -c --change REV           change made by revision

   -I --include PATTERN [+]  include names matching the given patterns

   -X --exclude PATTERN [+]  exclude names matching the given patterns

  [+] marked option can be specified multiple times

  use "hg -v help falabala" to show global options

  $ hg ci -d '0 0' -mtest1

  $ echo b >> a

  $ hg ci -d '1 0' -mtest2

Should diff cloned files directly:

  $ hg falabala -r 0:1

  diffing a.8a5febb7f867/a a.34eed99112ab/a

  [1]

Test diff during merge:

  $ hg update -C 0

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ echo c >> c

  $ hg add c

  $ hg ci -m "new branch" -d '1 0'

  created new head

  $ hg merge 1

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

Should diff cloned file against wc file:

  $ hg falabala

  diffing a.2a13a4d2da36/a $TESTTMP/a/a

  [1]

Test --change option:

  $ hg ci -d '2 0' -mtest3

  $ hg falabala -c 1

  diffing a.8a5febb7f867/a a.34eed99112ab/a

  [1]

Check diff are made from the first parent:

  $ hg falabala -c 3 || echo "diff-like tools yield a non-zero exit code"

  diffing a.2a13a4d2da36/a a.46c0e4daeb72/a

  diff-like tools yield a non-zero exit code

Test extdiff of multiple files in tmp dir:

  $ hg update -C 0 > /dev/null

  $ echo changed > a

  $ echo changed > b

  $ chmod +x b

Diff in working directory, before:

  $ hg diff --git

  diff --git a/a b/a

  --- a/a

  +++ b/a

  @@ -1,1 +1,1 @@

  -a

  +changed

  diff --git a/b b/b

  old mode 100644

  new mode 100755

  --- a/b

  +++ b/b

  @@ -1,1 +1,1 @@

  -b

  +changed

Edit with extdiff -p:

Prepare custom diff/edit tool:

  $ cat > 'diff tool.py' << EOT

  > #!/usr/bin/env python

  > import time

  > time.sleep(1) # avoid unchanged-timestamp problems

  > file('a/a', 'ab').write('edited\n')

  > file('a/b', 'ab').write('edited\n')

  > EOT

  $ chmod +x 'diff tool.py'

will change to /tmp/extdiff.TMP and populate directories a.TMP and a

and start tool

  $ hg extdiff -p "`pwd`/diff tool.py"

  [1]

Diff in working directory, after:

  $ hg diff --git

  diff --git a/a b/a

  --- a/a

  +++ b/a

  @@ -1,1 +1,2 @@

  -a

  +changed

  +edited

  diff --git a/b b/b

  old mode 100644

  new mode 100755

  --- a/b

  +++ b/b

  @@ -1,1 +1,2 @@

  -b

  +changed

  +edited

Test extdiff with --option:

  $ hg extdiff -p echo -o this -c 1

  this a.8a5febb7f867/a a.34eed99112ab/a

  [1]

  $ hg falabala -o this -c 1

  diffing this a.8a5febb7f867/a a.34eed99112ab/a

  [1]