cat: test output path behvaior when target path does not exist

In the next patch, we will change the behavior of the cat command to create
output file parent directories before attempting to write the output file.
This patch documents the current unfortunate behavior.

Differential Revision: https://phab.mercurial-scm.org/D1331

tests/test-cat.t

@@ -1,121 +1,132 b''
   $ hg init
   $ echo 0 > a
   $ echo 0 > b
   $ hg ci -A -m m
   adding a
   adding b
   $ hg rm a
   $ hg cat a
   0
   $ hg cat --decode a # more tests in test-encode
   0
   $ echo 1 > b
   $ hg ci -m m
   $ echo 2 > b
   $ hg cat -r 0 a
   0
   $ hg cat -r 0 b
   0
   $ hg cat -r 1 a
   a: no such file in rev 7040230c159c
   [1]
   $ hg cat -r 1 b
   1
 
 Test multiple files
 
   $ echo 3 > c
   $ hg ci -Am addmore c
   $ hg cat b c
   1
   3
   $ hg cat .
   1
   3
   $ hg cat . c
   1
   3
 
 Test fileset
 
   $ hg cat 'set:not(b) or a'
   3
   $ hg cat 'set:c or b'
   1
   3
 
   $ mkdir tmp
   $ hg cat --output tmp/HH_%H c
   $ hg cat --output tmp/RR_%R c
   $ hg cat --output tmp/h_%h c
   $ hg cat --output tmp/r_%r c
   $ hg cat --output tmp/%s_s c
   $ hg cat --output tmp/%d%%_d c
   $ hg cat --output tmp/%p_p c
   $ hg log -r . --template "{rev}: {node|short}\n"
   2: 45116003780e
   $ find tmp -type f | sort
   tmp/.%_d
   tmp/HH_45116003780e3678b333fb2c99fa7d559c8457e9
   tmp/RR_2
   tmp/c_p
   tmp/c_s
   tmp/h_45116003780e
   tmp/r_2
 
 Test template output
 
   $ hg --cwd tmp cat ../b ../c -T '== {path} ({abspath}) ==\n{data}'
   == ../b (b) == (glob)
   1
   == ../c (c) == (glob)
   3
 
   $ hg cat b c -Tjson --output -
   [
    {
     "abspath": "b",
     "data": "1\n",
     "path": "b"
    },
    {
     "abspath": "c",
     "data": "3\n",
     "path": "c"
    }
   ]
 
   $ hg cat b c -Tjson --output 'tmp/%p.json'
   $ cat tmp/b.json
   [
    {
     "abspath": "b",
     "data": "1\n",
     "path": "b"
    }
   ]
   $ cat tmp/c.json
   [
    {
     "abspath": "c",
     "data": "3\n",
     "path": "c"
    }
   ]
 
 Test working directory
 
   $ echo b-wdir > b
   $ hg cat -r 'wdir()' b
   b-wdir
 
 Environment variables are not visible by default
 
   $ PATTERN='t4' hg log -r '.' -T "{ifcontains('PATTERN', envvars, 'yes', 'no')}\n"
   no
 
 Environment variable visibility can be explicit
 
   $ PATTERN='t4' hg log -r '.' -T "{envvars % '{key} -> {value}\n'}" \
   >                 --config "experimental.exportableenviron=PATTERN"
   PATTERN -> t4
+
+Test behavior of output when directory structure does not already exist
+
+  $ mkdir foo
+  $ echo a > foo/a
+  $ hg add foo/a
+  $ hg commit -qm "add foo/a"
+  $ mkdir output
+  $ hg cat --output "output/%p" foo/a
+  abort: No such file or directory: output/foo/a
+  [255]