tests: use portable diff script via extdiff extension

Before this patch, some tests using external "diff" command via
extdiff extension fail on Solaris, because of incompatibility of
"diff" command and its output.

For example, system standard "diff" (= /usr/bin/diff) on Solaris
differs from GNU diff in points below:

  - "-N" (treat absent files as empty) option isn't supported

  - files are examined not in dictionary order
    (maybe, in order in storage)

This patch introduces portable diff script "pdiff" and make tests use
it via extdiff extension.

For portability of tests, this patch invokes "pdiff" script with
explicit "sh", because standard shell of runtime platform ("cmd.exe"
on Windows) is used at first to invoke external diff command.

tests/pdiff

@@ -0,0 +1,58 b''
+#!/bin/sh
+
+# Script to get stable diff output on any platform.
+#
+# Output of this script is almost equivalent to GNU diff with "-Nru".
+#
+# Use this script as "hg pdiff" via extdiff extension with preparation
+# below in test scripts:
+#
+#   $ cat >> $HGRCPATH <<EOF
+#   > [extdiff]
+#   > pdiff = sh "$RUNTESTDIR/pdiff"
+#   > EOF
+
+filediff(){
+    # USAGE: filediff file1 file2 [header]
+
+    # compare with /dev/null if file doesn't exist (as "-N" option)
+    file1="$1"
+    if test ! -f "$file1"; then
+        file1=/dev/null
+    fi
+    file2="$2"
+    if test ! -f "$file2"; then
+        file2=/dev/null
+    fi
+
+    if cmp -s "$file1" "$file2"; then
+        # Return immediately, because comparison isn't needed. This
+        # also avoids redundant message of diff like "No differences
+        # encountered" (on Solaris)
+        return
+    fi
+
+    if test -n "$3"; then
+        # show header only in recursive case
+        echo "$3"
+    fi
+
+    # replace "/dev/null" by corresponded filename (as "-N" option)
+    diff -u "$file1" "$file2" |
+    sed "s@^--- /dev/null\(.*\)\$@--- $1\1@" |
+    sed "s@^\+\+\+ /dev/null\(.*\)\$@+++ $2\1@"
+}
+
+if test -d "$1" -o -d "$2"; then
+    # ensure comparison in dictionary order
+    (
+    if test -d "$1"; then (cd "$1" && find . -type f); fi
+    if test -d "$2"; then (cd "$2" && find . -type f); fi
+    ) |
+    sed 's@^\./@@g' | sort | uniq |
+    while read file; do
+        filediff "$1/$file" "$2/$file" "diff -Nru $1/$file $2/$file"
+    done
+else
+    filediff "$1" "$2"
+fi

tests/test-graft.t

@@ -1,7 +1,7 b''
   $ cat >> $HGRCPATH <<EOF
-  > [defaults]
-  > # for portability
-  > extdiff = --option -Nru
+  > [extdiff]
+  > # for portability:
+  > pdiff = sh "$RUNTESTDIR/pdiff"
   > EOF
 
 Create a repo with some stuff in it:
@@ -348,7 +348,7 b' Disallow grafting an already grafted cse'
   skipping already grafted revision 7:ef0ef43d49e7 (was grafted from 2:5c095ad7e90f)
   [255]
 
-  $ hg extdiff --config extensions.extdiff= --patch -r 2 -r 13
+  $ hg pdiff --config extensions.extdiff= --patch -r 2 -r 13
   --- */hg-5c095ad7e90f.patch	* (glob)
   +++ */hg-7a4785234d87.patch	* (glob)
   @@ -1,18 +1,18 @@
@@ -379,7 +379,7 b' Disallow grafting an already grafted cse'
   ++a
   [1]
 
-  $ hg extdiff --config extensions.extdiff= --patch -r 2 -r 13 -X .
+  $ hg pdiff --config extensions.extdiff= --patch -r 2 -r 13 -X .
   --- */hg-5c095ad7e90f.patch	* (glob)
   +++ */hg-7a4785234d87.patch	* (glob)
   @@ -1,8 +1,8 @@

tests/test-largefiles-update.t

@@ -6,9 +6,9 b' directory (and ".hg/largefiles/dirstate"'
   > merge = internal:fail
   > [extensions]
   > largefiles =
-  > [defaults]
-  > # for portability
-  > extdiff = --option -Nru
+  > [extdiff]
+  > # for portability:
+  > pdiff = sh "$RUNTESTDIR/pdiff"
   > EOF
 
   $ hg init repo
@@ -23,7 +23,7 b' directory (and ".hg/largefiles/dirstate"'
   $ echo 'large1 in #1' > large1
   $ echo 'normal1 in #1' > normal1
   $ hg commit -m '#1'
-  $ hg extdiff -r '.^' --config extensions.extdiff=
+  $ hg pdiff -r '.^' --config extensions.extdiff=
   diff -Nru repo.0d9d9b8dc9a3/.hglf/large1 repo/.hglf/large1
   --- repo.0d9d9b8dc9a3/.hglf/large1	* (glob)
   +++ repo/.hglf/large1	* (glob)

tests/test-subrepo-deep-nested-change.t

@@ -1,7 +1,7 b''
   $ cat >> $HGRCPATH <<EOF
-  > [defaults]
-  > # for portability
-  > extdiff = --option -Nru
+  > [extdiff]
+  > # for portability:
+  > pdiff = sh "$RUNTESTDIR/pdiff"
   > EOF
 
 Preparing the subrepository 'sub2'
@@ -717,9 +717,9 b' Restore the trashed subrepo tracking'
 
 Interaction with extdiff, largefiles and subrepos
 
-  $ hg --config extensions.extdiff= extdiff -S
+  $ hg --config extensions.extdiff= pdiff -S
 
-  $ hg --config extensions.extdiff= extdiff -r '.^' -S
+  $ hg --config extensions.extdiff= pdiff -r '.^' -S
   diff -Nru cloned.*/.hgsub cloned/.hgsub (glob)
   --- cloned.*/.hgsub	* (glob)
   +++ cloned/.hgsub	* (glob)
@@ -734,7 +734,7 b' Interaction with extdiff, largefiles and'
   -b1a26de6f2a045a9f079323693614ee322f1ff7e sub3
   [1]
 
-  $ hg --config extensions.extdiff= extdiff -r 0 -r '.^' -S
+  $ hg --config extensions.extdiff= pdiff -r 0 -r '.^' -S
   diff -Nru cloned.*/.hglf/b.dat cloned.*/.hglf/b.dat (glob)
   --- cloned.*/.hglf/b.dat	* (glob)
   +++ cloned.*/.hglf/b.dat	* (glob)
@@ -799,7 +799,7 b' Interaction with extdiff, largefiles and'
   [1]
 
   $ echo mod > sub1/sub2/sub2
-  $ hg --config extensions.extdiff= extdiff -S
+  $ hg --config extensions.extdiff= pdiff -S
   --- */cloned.*/sub1/sub2/sub2	* (glob)
   +++ */cloned/sub1/sub2/sub2	* (glob)
   @@ -1* +1* @@ (glob)