tests/test-unified-test.t

run-tests.py: add RUNTESTDIR to refer `tests` of Mercurial

Before this patch, there is no way to refer files under `tests` or so
of Mercurial source tree, when `run-tests.py` runs in `tests` of third
party tools. In this case, `TESTDIR` refers the latter `tests`.

This prevents third party tools from using useful tools in Mercurial
source tree (e.g. `contrib/check-code.py`).

This patch adds `RUNTESTDIR` environment variable to refer `tests` of
Mercurial source tree, in which `run-tests.py` now running is
placed. For example, tests of third party tools can refer
`contrib/check-code.py` in Mercurial source tree as
`$RUNTESTDIR/../contrib/check-code.py`.

BTW, for similarity with `TESTDIR` referring `test*s*` directory,
newly added environment variable isn't named as `RUNTEST*S*DIR`. In
addition to it, the corresponded local variable is also named as
`runtestdir`.

This is a one of preparations for issue4677.

Test that the syntax of "unified tests" is properly processed
==============================================================

Simple commands:

  $ echo foo
  foo
  $ printf 'oh no'
  oh no (no-eol)
  $ printf 'bar\nbaz\n' | cat
  bar
  baz

Multi-line command:

  $ foo() {
  >     echo bar
  > }
  $ foo
  bar

Return codes before inline python:

  $ sh -c 'exit 1'
  [1]

Doctest commands:

  >>> print 'foo'
  foo
  $ echo interleaved
  interleaved
  >>> for c in 'xyz':
  ...     print c
  x
  y
  z
  >>> print
  
  >>> foo = 'global name'
  >>> def func():
  ...     print foo, 'should be visible in func()'
  >>> func()
  global name should be visible in func()
  >>> print '''multiline
  ... string'''
  multiline
  string

Regular expressions:

  $ echo foobarbaz
  foobar.* (re)
  $ echo barbazquux
  .*quux.* (re)

Globs:

  $ printf '* \\foobarbaz {10}\n'
  \* \\fo?bar* {10} (glob)

Literal match ending in " (re)":

  $ echo 'foo (re)'
  foo (re)

Windows: \r\n is handled like \n and can be escaped:

#if windows
  $ printf 'crlf\r\ncr\r\tcrlf\r\ncrlf\r\n'
  crlf
  cr\r (no-eol) (esc)
  \tcrlf (esc)
  crlf\r (esc)
#endif

Combining esc with other markups - and handling lines ending with \r instead of \n:

  $ printf 'foo/bar\r'
  fo?/bar\r (no-eol) (glob) (esc)
#if windows
  $ printf 'foo\\bar\r'
  foo/bar\r (no-eol) (glob) (esc)
#endif
  $ printf 'foo/bar\rfoo/bar\r'
  foo.bar\r \(no-eol\) (re) (esc)
  foo.bar\r \(no-eol\) (re)

testing hghave

  $ hghave true
  $ hghave false
  skipped: missing feature: nail clipper
  [1]
  $ hghave no-true
  skipped: system supports yak shaving
  [1]
  $ hghave no-false

Conditional sections based on hghave:

#if true
  $ echo tested
  tested
#else
  $ echo skipped
#endif

#if false
  $ echo skipped
#else
  $ echo tested
  tested
#endif

#if no-false
  $ echo tested
  tested
#else
  $ echo skipped
#endif

#if no-true
  $ echo skipped
#else
  $ echo tested
  tested
#endif

Exit code:

  $ (exit 1)
  [1]