\input texinfo @c -*-texinfo-*-
@finalout

@settitle Greg testing framework
@setfilename greg.info
@c
@c This file documents the GNUstep-Guile Regression testing framework `Greg'
@c
@c Copyright (C) 1998 Free Software Foundation, Inc.
@c
@c This text may be freely distributed under the terms of the GNU
@c General Public License.
@c

@ifinfo
@format
START-INFO-DIR-ENTRY
* Greg: (greg).            Another GNU testing framework.
END-INFO-DIR-ENTRY
@end format
@end ifinfo

@syncodeindex ky cp
@syncodeindex fn cp

@setchapternewpage odd
@settitle Greg testing framework
@titlepage
@title The Greg testing framework
@subtitle for Greg Version @VERSION@
@sp 1
@subtitle November 1998
@author Richard Frith-Macdonald <richard@@brainstorm.co.uk>
@page

@vskip 0pt plus 1filll
Copyright @copyright{} 1998 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@noindent
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.
@end titlepage

@ifinfo
Copyright @copyright{} 1998 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
@end ignore

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.

@node Top, Copying, ,
@top Greg

Greg is a framework for running test suites on software tools.
Greg was developed for the 
@uref{http://www.gnustep.org/,GNUstep} project.

This file describes version @VERSION@ of Greg.

@menu
* Copying::		GNU Library
* News::                New in this release
* Overview::            Greg in brief
* Installation::	Installing Greg
* Invoking Greg::	How to run tests
* Writing tests::	How to write a testsuite
* Index::               Index
@end menu
@end ifinfo

@iftex
@raggedbottom
@end iftex

@node Copying, News, Top, Top
@chapter Copying

See the file @emph{COPYING.LIB}.

@node News, Overview, Copying, Top
@chapter New in this release
@cindex News

New in 0.6

@itemize @bullet
@item
Converted makefiles to work without GNUstep
@item
Improved configuration code
@item
Improved documentation somewhat
@item
Updated to work with guile version 1.3
@end itemize

New in 0.5

@itemize @bullet
@item
greg-testcase now returns a useful result.
@item
Fixed bug in creating child processes on some systems.
@end itemize

New in 0.4

@itemize @bullet
@item
Allow an empty string as the program name for creating a child process -
in which case, we fork without execing to another program.
Modified Greg to allow @emph{(quit)} to exit from the test system.
@end itemize

New in 0.3

@itemize @bullet
@item
Improved installation - now checks for location of guile shell.
@item
Fixed a couple of minor errors in the documentation.
@end itemize

New in 0.2

@itemize @bullet
@item
Ported to Unixware 2.1.3 - should work for any SysV4.2 based unix.
@end itemize

General news

This release of Greg provides a test framework much like that of
DejaGNU, but also provides Guile modules to permit `embedded' testing of
applications that use Guile as a scripting language and libraries that
are directly accessible to Guile.

This release has been tested with Guile-1.2 and 1.3

Apologies to Guile/Scheme/Lisp programmers out there - I came to this from
Objective-C programming and taught myself during the last four weeks while
I wrote GNUstep-Guile an Greg - so my code is probably really ugly - but it
does seem to work.

The code to run a child process in a pseudo-terminal works for
GNU/Linux and SysV4.2 systems - it probably needs work to make it
more portable -
Please email bugfixes and comments to <richard@@brainstorm.co.uk>

@node Overview, Installation, News, Top
@chapter Greg in brief
@cindex overview

Greg is a framework for testing other programs and libraries.
Its purpose is to provide a single front end for all tests and to
be a small, simple framework for writing tests.
Greg leverages off the Guile language to provide all the power (and more)
of other test frameworks with greater simplicity and ease of use.

The simplicity of the Greg framework makes it easy to write tests for
any program, but it was specifically written for use with GNUstep-Guile
to permit direct testing of the
@uref{http://www.gnustep.org/,GNUstep} libraries without the
necessity to run a separate driver program.

The core functionality of Greg is a Guile module which can be loaded
into any software with an embedded Guile interpreter.  Any program
which uses Guile as it's scripting language can therefore use Greg
to test itself directly!

For testing external programs, Greg provides a compiled module that may
be dynamically linked into Guile to permit you to run an application as
a child process on a pseudo-terminal.  In conjunction with the standard
Guile `expect' module, this lets you test external programs.

Also provided is @emph{greg} - a Guile script to invoke the Greg test
framework in much the same way that @emph{runtest} is used in DejaGNU.

All tests have the same output format (enforced by the @emph{greg-testcase}
procedure).
Greg's output is designed to be both readable and readily parsed by other
software, so that it can be used as input to customised testing processes.

Greg provides most of the functionality of DejaGNU but is rather simpler.
It omits specific support for cross-platform/remote testing since this is
really rather trivial to add where required and tends to vary from site to
site so much that an attempt at a generic solution is pretty pointless.
What Greg does do, is provide hooks to let you easily introduce site
specific code for handling those sorts of situations.

The current version of Greg can normally be found on GNU ftp sites and
at
@uref{http://www.tiptree.demon.co.uk/gstep/guile/greg-@VERSION@.tar.gz}
with documentation online at
@uref{http://www.tiptree.demon.co.uk/gstep/guile/gregdoc_toc.html}

or, for the bleeding edge - availably by anonymous cvs as part of the
GNUstep-Guile package in the GNUstep project -

CVSROOT=":pserver:anoncvs@@cvs.net-community.com:/gnustep"@*
export CVSROOT@*
cvs login (password is `anoncvs')@*
cvs -z3 checkout guile@*

@menu
* Running Tests::               How to run a Greg testsuite
* Sample Test::                 A trivial example of a testcase
* Design Goals::                Why Greg does what it does
* Posix::			Greg conforms to POSIX 1003.3
@end menu

@node Running Tests
@section How to run a Greg testsuite
@cindex existing tests, running
@cindex running tests
@cindex tests, running

@kindex make check
To run tests from an existing collection, try running

@example
make check
@end example

@cindex @code{check} makefile target
If the @code{check} target exists, it usually saves you some
trouble---for instance, it can set up any auxiliary programs or other
files needed by the tests.

Alternatively, if you are in the top-level source directory of an existing
testsuite (ie. there are subdirectories containing files with a @code{.scm}
extension), you can get the @emph{greg} script to test all the tools in the
directory by typing  -

@example
greg
@end example


If you have a test suite that is intended to be used for `embedded' testing -
You need to start the application to be tested, gain access to it's Guile
command line (or other guile interface) and enter the commands -

@example
(use-modules (ice-9 greg))
(greg-test-all)
@end example

@node Sample Test
@section A trivial example of a testcase

@cindex example
Each Greg test is a @code{Guile} script; the tests vary widely in
complexity, depending on the nature of the tool and the feature tested.

@cartouche
@smallexample
;
; GNUstep-guile interface library test
;
; Create an object using the NSString [stringWithCString:] method and
; check that the resulting object is of the correct class.
;
(greg-testcase "The `stringWithCString:' method creates an NSString object" #t
(lambda ()
  (define obj ([] "NSString" stringWithCString: "Hello world"))
  (gstep-bool ([] obj isKindOfClass: ([] "NSString" class)))
))
@end smallexample
@end cartouche

Though brief, this example is a complete test.  It illustrates some of
the main features of Greg test scripts:

@itemize @bullet
@item
The test case does not deal with accessing the library - the Guile interpreter
in use is linked with the library.  If you were testing an external application
which needed to be started up as a child process running on a pseudo-terminal,
the process startup would have been performed in a separate @emph{begin.grg}
script.

@item
You use the Guile programming language to write the script and, in this case,
the builtin macros and procedures (such as @code{gstep-bool} and @code{[]}
provided by the GNUstep-Guile library.

@item
Test cases use the procedure @code{greg-testcase} to record the test outcome.
You pass this procedure a string (`assertion') describing the testcase,
a boolean specifying the expected outcome, and a `thunk' (parameterless
procedure) that performs the actual test.@*
The `thunk' is normally a `lambda expression' - you can look these up in the
Guile/Scheme documentation  - or just follow the example.

@item
As much code as possible is placed inside the `thunk' passed to
@code{greg-testcase} so that, in the event of an error, the @code{greg-testcase}
procedure can trap it and report an unresolved test.@*
The code - 
@code{(define obj ([] "NSString" stringWithCString: "Hello world"))} could have
appeared outside the testcase, but that would have been less safe.

@end itemize

@node Design Goals
@section Why Greg does what it does
@cindex design goals

Greg was written to support regression testing for the
@uref{http://www.gnustep.org/,GNUstep} libraries.
It was inspired by an earlier test framework (by Ovidiu Predescu) that used
DejaGNU along with a `driver' program (to make the calls to the library) and
a suite of TcL scripts to control the driver.

There were three main problems (inherent in the nature of DejaGNU) with that
approach -

@itemize @bullet

@item Writing/Debugging tests was a pain - errors in the TcL code of a testcase
could all too easily interfere with the TcL routines that interfaced to the
driver program.@*
Solution - use another language where errors in testcases are localised.

@item Writing/Debugging tests was a pain - you needed to attach gdb to the
driver program that was running as a child of the DejaGNU process in order
to debug errors in the driver/library under test.@*
Solution - `embedded testing' make the test framework and the code under
test part of the process, so it's easy to run the whole thing under gdb.

@item The driver program and TcL scripts required quite a bit of support
when adding new tests.@*
Solution - `embedded testing' we needed to remove the intermediary layers
and test as directly as possible.

@end itemize

So, something different was required, a test framework in a safer, simpler
language that made it easy to create thin interfaces to libraries, so
simplifying the task of producing testcases.

Of course, the good points of DejaGNU needed to be retained - clear
output, Posix compliance, the ability to test separate programs as well
as libraries.

A couple of additional goals seemed worthwhile -

@itemize @bullet
@item Make the test framework flexible so that applications could easily
use it for self-testing.

@item Give the framework a similar structure to, and a user interface like
that of DejaGNU, so that people with a background in testing could easily
adopt it.
@end itemize

Hopefully, Greg meets all its goals.

@node Posix
@section A POSIX conforming test framework

@cindex POSIX conformance
@cindex standard conformance: POSIX 1003.3

This section is copied almost directly from the DejaGNU documentation
with minor modifications -

Greg is believed to conform to the @sc{posix} standard for test frameworks.

@sc{posix} standard 1003.3 defines what a testing framework needs to
provide, in order to permit the creation of @sc{posix} conformance
test suites. This standard is primarily oriented to running @sc{posix}
conformance tests, but its requirements also support testing of features
not related to @sc{posix} conformance.

The @sc{posix} documentation refers to @dfn{assertions}.  An assertion
is a description of behavior.  For example, if a standard says ``The sun
shall shine'', a corresponding assertion might be ``The sun is
shining.''  A test based on this assertion would pass or fail depending
on whether it is daytime or nighttime.  It is important to note that the
standard being tested is never 1003.3; the standard being tested is some
other standard, for which the assertions were written.

As there is no test suite to test @emph{testing frameworks} for
@sc{posix} 1003.3 conformance, verifying conformance to this standard is
done by repeatedly reading the standard and experimenting.  One of the
main things 1003.3 does specify is the set of allowed output messages,
and their definitions.  Four messages are supported for a required
feature of @sc{posix} conforming systems, and a fifth for a conditional
feature. Greg supports the use of all five output messages; in this
sense a test suite that uses exactly these messages can be considered
@sc{posix} conforming.  These definitions specify the output of a test
case:

@ftable @code
@cindex success, POSIX definition
@item PASS
A test has succeeded.  That is, it demonstrated that the assertion is true.

@cindex UPASS, avoiding for POSIX
@item UPASS
@sc{posix} 1003.3 does not incorporate the notion of unexpected passes,
so for strict @sc{posix}, @code{PASS}, instead of @code{UPASS}, is returned
for test cases which were not expected to pass but did.  This means that
@code{PASS} is in some sense more ambiguous than if @code{UPASS} is also
used.

@item FAIL
@cindex failure, POSIX definition
A test @emph{has} produced the bug it was intended to capture.  That is,
it has demonstrated that the assertion is false.  The @code{FAIL}
message is based on the test case only.  Other messages are used to
indicate a failure of the framework.

@cindex XFAIL, avoiding for POSIX
@item XFAIL
@sc{posix} 1003.3 does not incorporate the notion of expected failures,
so for strict @sc{posix}, @code{FAIL}, instead of @code{XFAIL}, is returned
for test cases which were expected to fail and did not.  This means that
@code{FAIL} is in some sense more ambiguous than if @code{XFAIL} is also
used.

@item UNRESOLVED
@cindex ambiguity, required for POSIX
A test produced indeterminate results.  Usually, this means the test
executed in an unexpected fashion; this outcome requires that a human
being go over results, to determine if the test should have passed or
failed.  This message is also used for any test that requires human
intervention because it is beyond the abilities of the testing
framework.  Any unresolved test should resolved to @code{PASS} or
@code{FAIL} before a test run can be considered finished.

Note that for @sc{posix}, each assertion must produce a test result
code.  If the test isn't actually run, it must produce @code{UNRESOLVED}
rather than just leaving that test out of the output.  With Greg this is
not a problem - any unexpected termination of a @emph{greg-testcase}
procedure will produce @code{UNRESOLVED}.

Here are some of the ways a test may wind up @code{UNRESOLVED}:

@itemize @bullet
@item
A test's execution is interrupted.

@item
A test does not produce a clear result. This is usually because there
was a Guile exception thrown while processing the test.
This usually requires a human being to examine the output to
determine what really happened---and to improve the test case.

@item
A test depends on a previous test, which fails.

@item
The test was set up incorrectly and failed to produce a boolean value.
@end itemize

@item UNTESTED
A test was not run.  This is a placeholder, used when there is no
real test case yet.
@end ftable

@noindent
The only remaining output message left is intended to test features that
are specified by the applicable @sc{posix} standard as conditional:

@ftable @code
@item UNSUPPORTED
There is no support for the tested case.  This may mean that a
conditional feature of an operating system, or of a compiler, is not
implemented.
@end ftable
  
Greg uses the same output procedures to produce these messages for
all test suites, and these procedures are already known to conform to
@sc{posix} 1003.3.  For a Greg test suite to conform to @sc{posix}
1003.3, you must set the variable @code{greg-posix} to be true (or run
the @code{greg} command with the @code{--posix} flag).
Doing this will ensure that non-posix extensions are not used.

@node Installation, Invoking Greg, Overview, Top
@chapter Installing Greg
@cindex installing

@subsection Requirements
@cindex requirements

Greg needs to have Guile installed.  It should work with Guile-1.2
or later (it has been tested with 1,2 and 1.3).
You need to have the @emph{guile} program in your path in
order for the installation process to determine the proper locations
for things.

You can get Guile from any GNU ftp site.

You can get Greg either as part of the GNUstep-Guile package at
@url{http://www.tiptree.demon.co.uk/gstep/guile/gstep-guile.tar.gz}
or separately at
@url{http://www.tiptree.demon.co.uk/gstep/guile/greg.tar.gz}

@subsection Building
@cindex building Greg

To build Greg - 

Type @emph{./configure} in the main Greg directory to configure for
your system.

Once configuration is complete, go into the `Library' subdirectory and
type @emph{make install} to build and install things.

You should end up with -

A compiled module, which can be dynamically linked into Guile with
@emph{(use-modules (greg compiled))},

a module defining Guile procedures and variables providing the main
test framework, which can be accessed using
@emph{(use-modules (ice-9 greg))},

and a Guile script that you can use to run tests from the unix
command-line (@emph{greg}).

You @emph{MUST} install Greg before you attempt to use it (or run it's
self-tests) because the Guile modules making it up must be in place in
the standard Guile directories before Greg can work.

Once Greg is installed, you can type @emph{make check} in the Tests
directory to get Greg to test itself.

You can type @emph{make} in the Documentation directory to build the
documentation in @emph{info}, @emph{html} and @emph{dvi} formats.

NB.@*
You must have the @emph{makeinfo} program installed to build the
documentation in info format @*
You must have the @emph{texi2html} program installed to build the
documentation in html format @*
You must have the @emph{texi2dvi} program installed to build the
documentation in dvi format @*

@subsection Problems
@cindex problems
@cindex troubleshooting

Greg is quite simple, so there is not much to go wrong with it.
Of course, you must have a working copy of Guile installed, and you need
to make sure you ran the configure script to configure Greg for your system,
and installed Greg, but after that, most stuff should just work.

The single area where you are most likely to encounter problems is if you are
using Greg to test external programs run in a child process using the
@emph{(greg-child)} procedure.  The @emph{C} code for this procedure is quite
system-dependent and has only been tested on a few operating systems.
If you have problems with this, look at @emph{greg.c} in the Library
directory.  Please attempt to make a patch to fix things on your
operating-system and send it to me - <richard@@brainstorm.co.uk>

@node Invoking Greg, Writing tests, Installation, Top
@chapter Using @code{greg}
@cindex invoking
@cindex running

The Greg framework is designed to be used in two ways - as an embedded
system from within any application which is linked with the Guile library,
or stand-alone using the command-line @code{greg} driver script.
For both of these methods of usage the test cases are written the same
way and the expected output is the same.

@menu
* Output::			Expected output format from a Greg test
* Files and directories::	The layout of files and directories
* Embedded usage::		What does a Greg test case look like?
* Command-line usage::		Using the @code{greg} script.
@end menu

@node Output
@section Output

While Greg may produce more verbose output in response to various settings,
the basic output of a test run is a series of lines describing the
success/failure state of each testcase encountered, followed by a
summary of all test cases.

In `normal' mode, only unexpected results are displayed, but in `verbose'
output mode, results for @emph{all} results are displayed.

@code{greg} flags the outcome of each test case with a line consisting of
one of the following codes followed by a colon, a space, and then the
testcase description.

@table @code
@item PASS
@kindex PASS
@cindex successful test
@cindex test, successful
The most desirable outcome: the test succeeded, and was expected to
succeed.

@item UPASS
@kindex UPASS
@cindex successful test, unexpected
@cindex unexpected success
A pleasant kind of failure: a test was expected to fail, but succeeded.
This may indicate progress; inspect the test case to determine whether
you should amend it to stop expecting failure.

@item FAIL
@kindex FAIL
@cindex failing test, unexpected
@cindex test, failing
A test failed, although it was expected to succeed.  This may indicate
regress; inspect the test case and the failing software to locate the bug.

@item XFAIL
@kindex XFAIL
@cindex expected failure
@cindex failing test, expected
A test failed, but it was expected to fail.  This result indicates no
change in a known bug.  If a test fails because the operating system
where the test runs lacks some facility required by the test, the
outcome is @code{UNSUPPORTED} instead.

@item UNRESOLVED
@kindex UNRESOLVED
@cindex test, unresolved outcome
Output from a test requires manual inspection; the test suite could not
automatically determine the outcome.  For example, your tests can report
this outcome is when a test does not complete as expected.

@item UNTESTED
@kindex UNTESTED
@cindex untested properties
A test case is not yet complete, and in particular cannot yet produce a
@code{PASS} or @code{FAIL}.  You can also use this outcome in dummy
``tests'' that note explicitly the absence of a real test case
for a particular property.

@item UNSUPPORTED
@kindex UNSUPPORTED
@cindex unsupported test
@cindex test, unsupported
A test depends on a conditionally available feature that does not exist
(in the configured testing environment).  For example, you can use this
outcome to report on a test case that does not work on a particular
target because its operating system support does not include a required
subroutine.
@end table

@node Files and directories
@section Files and directories
@cindex files and directories
@cindex directories and files

A Greg test run expects to find files and directories in a certain layout
(modeled on that used by DejaGNU).

The test source directory (normally your current directory) is expected to
contain one or more @emph{tool} directories.  Each @emph{tool} directory
should contain one or more @emph{test} scripts.  In fact any file in a
@emph{tool} directory which has a @emph{.scm} extension is assumed to be
a Guile @emph{test} script.

When a normal Greg test run is done, Greg goes through each @emph{tool}
directory in turn and loads each @emph{test} script in turn.

You may set the Guile variable @emph{greg-tools} or use the @emph{--tools ...}
command-line option to specify a list of tools directories to use rather than
assuming that @emph{all} subdirectories are @emph{tool} directories.
If you do this, the tools are tested in the order in which they appear in
the list rather than the default order (ASCII sorted by name).

You may set the Guile variable @emph{greg-files} or use the @emph{--files ...}
command-line option to specify a list of file names to use rather than
assuming that @emph{all} @emph{.scm} files in each @emph{tool} directory are
test scripts.
If you do this, the files are loaded in the order in which they appear in
the list.

@cindex begin.grg
@cindex end.grg
@cindex cleanup
@cindex initialisation

As a (minor) complication to this simple layout, Greg permits the use of
@emph{begin.grg} and @emph{end.grg} scripts in both the main source directory
and in each @emph{tool} directory.  These scripts permit you to add any
initialisation and cleanup code you want.  Typically (for non-embedded
testing) you would use a @emph{begin.grg} script to start the application
to be tested.

If @emph{begin.grg} exists in the main source directory, it will be loaded
before any tools are tested.

If @emph{end.grg} exists in the main source directory, it will be loaded
after all the tools are tested.

If @emph{begin.grg} exists in a @emph{tool} directory, it will be loaded
before any @emph{test} scripts in that directory are loaded.

If @emph{end.grg} exists in a @emph{tool} directory, it will be loaded
after all the @emph{test} scripts in that directory are loaded.

@node Embedded usage
@section Embedded usage
@cindex embedded usage
@cindex module usage

Greg is designed primarily for embedded usage - any application that uses
Guile as it's scripting language should be able to use Greg to test itself.

To this end - Greg provides a Guile module containing definitions of
various procedures (used to run tests) and variables (used to modify the
behavior of a test run).

Before trying to use any part of Greg, You need to load the Greg module with
@emph{(use-modules (ice-9 greg))}

@cindex run test procedure
The main procedure to run Greg tests is @emph{(greg-test-run)}.
You can use this to run tests in much the same way as the @emph{greg} script
is used to run tests from the command-line.  The behavior of this
procedure is modified by setting the following top-level variables -

@cindex variables
@itemize @bullet

@item greg-debug
@cindex greg-debug
@cindex debug variable
The @emph{greg-debug} variable is a boolean used to determine whether to
output extra debug information.  The debug information is written to a
@emph{.dbg} file.  Test scripts may use the @emph{greg-dlog} procedure to
output debug information.

@item greg-files
@cindex greg-files
@cindex files variable
The @emph{greg-files} variable is a list of strings used to specify the names
of the test scripts to be run.  If this list is empty, all the files with the
@code{.scm} extension in a @emph{tool} subdirectory are loaded.  If the list
contains names, the named scripts are loaded in the order in which they occur
in the list rather than the default order (ASCII sorted by name).@*
The names of scripts in this list should @emph{not} contain the @code{.scm}
extension - it will be added automatically by Greg.

@item greg-obj-dir
@cindex greg-obj-dir
@cindex obj-dir variable
The @emph{greg-obj-dir} variable is a string naming the directory in which
Greg expects to find binaries to be run as child processes.@*
By default, this is the current directory (@code{.}).

@item greg-out-dir
@cindex greg-out-dir
@cindex out-dir variable
The @emph{greg-out-dir} variable is a string naming the directory in which
Greg will generate log and debug output files.@*
By default, this is the current directory (@code{.}).

@item greg-posix
@cindex greg-posix
@cindex posix variable
The @emph{greg-posix} variable is a boolean used to determine whether to
produce strict posix output, or permit non-posix extensions.

@item greg-src-dir
@cindex greg-src-dir
@cindex src-dir variable
The @emph{greg-src-dir} variable is a string naming the directory in which
Greg will look for @emph{tool} subdirectories and where it expects to find
the main initialisation and cleanup scripts
(@emph{begin.grg} and @emph{end.grg}) for a test run.@*
By default, this is the current directory (@code{.}).

@item greg-tools
@cindex greg-tools
@cindex tools variable
The @emph{greg-tools} variable is a list of strings used to specify the names
of the tools to be tested (ie the names of the subdirectories of the main
source directory).  If this list is empty, all the subdirectories of the
main source directory (normally @code{.}) are assumed to be valid @emph{tool}
directories.  If the list contains names, the named subdirectories are used
in the order in which they occur in the list.@*

@item greg-verbose
@cindex greg-verbose
@cindex verbose variable
The @emph{greg-verbose} variable is a number used to determine the level of
detail produced in the log output.  At zero (the default), only minimal
information is output (unexpected testcase results and a summary of the
number of testcases passed).  At one, the result of each testcase is reported
and a more detailed summary is output.  At two, entry and exit of tool
directories and test files is reported.

@end itemize

@node Command-line usage
@section Command-line usage

@cindex @code{greg} description
@cindex Greg test driver
@code{greg} is the executable test driver for Greg.  This is a Guile script
that you can use to run tests from the command line.
The command-line options that you can pass to @code{greg} are listed below.

@cindex exit code from @code{greg}
@cindex @code{greg} exit code
@code{greg} returns an exit code of @code{1} if any test
has an unexpected result; otherwise (if all tests pass or fail as
expected) it returns @code{0} as the exit code.

This is the full set of command line options that @code{greg}
recognizes.

@cindex command line options
@cindex options
@cindex @code{greg} option list
@cindex option list, @code{greg}
@smallexample
greg --tool @var{tool} @dots{}
[ --debug ]
[ --file @var{script} @dots{} ]
[ --help ]
[ --objdir @var{path} ]
[ --outdir @var{path} ]
[ --posix ]
[ --srcdir @var{path} ]
[ -v | --verbose ]  [ -V | --version ]
@end smallexample

@table @code
@item --tool @var{tool} @dots{}
@cindex selecting tests for a tool
@cindex @code{--tool} (@code{greg} option)
@var{tool} specifies what set of tests to run.  It provides a list of
subdirectories (each corresponding to a tool) in which test scripts
can be found.
Initialisation code (including executable tool startup) for each tool may
be placed in @file{begin.grg} in the appropriate tool subdirectory.
Cleanup code may be placed in @file{end.grg}.

For example, including @emph{--tool gcc} on the @code{greg} command
line runs tests from the @code{gcc} subdirectory.

The order in which the tools are tested will be the same as the order in
which the tool names occur on the command line.

@item --file @var{script} @dots{}
@cindex selecting a range of tests
@cindex tests, running specifically
@cindex naming tests to run
Specify the names of testsuites to run.
By default, @code{greg} runs all tests for the tool, but you can
restrict it to particular testsuites by giving the names of the @emph{.scm}
@code{guile} scripts that control them.  You do not need to supply the
@emph{.scm} file extension - it will be assumed.

@var{testsuite} may not include path information; use plain filenames.

The order in which the test scripts are run will be the same as the order in
which the script names occur on the command line.


@item --debug
@cindex @code{--debug} (@code{greg} option)
@cindex debug log for test cases
@cindex test cases, debug log
@cindex @code{tests.dbg} file
Turns on the @code{expect} internal debugging output.  Debugging output
is displayed as part of the @code{greg} output, and logged to a file
called @file{tests.dbg}.  The extra debugging output does @emph{not}
normally appear on standard output.

@item --help
@cindex @code{--help} (@code{greg} option)
@cindex help with @code{greg}
@cindex @code{greg}, listing options
Prints out a short summary of the @code{greg} options, then exits
(even if you also specify other options).

@item --objdir @var{path}
@cindex @code{--objdir} (@code{greg} option)
@cindex object directory
@cindex test programs, auxiliary
@cindex auxiliary test programs
Use @var{path} as the top directory containing any auxiliary compiled
test code. This defaults to @file{.}.  Use this option to locate
pre-compiled test code.  You can normally prepare any auxiliary files
needed with @code{make}.

@item --outdir @var{path}
@cindex output directory
@cindex @code{--outdir} (@code{greg} option)
@cindex log files, where to write
Write output logs in directory @var{path}.  The default is @emph{.}, the
directory where you start @code{greg}.  This option affects only the
log and the debug files @file{@var{tool}.log} and
@file{@var{tool}.dbg}.

@item --srcdir @var{path}
@cindex source directory
@cindex @code{--srcdir} (@code{greg} option)
Use @var{path} as the top directory for test scripts to run.
@code{greg} looks in this directory for any subdirectory whose name
matches any toolname (specified with @emph{--tool}).

@item --verbose
@itemx -v
@cindex @code{--verbose} (@code{greg} option)
@cindex @code{-v} (@code{greg} option)
@cindex turning on output
@cindex output, additional
By default, @code{greg} shows only the output of tests that produce unexpected
results; that is, tests with status @emph{FAIL} (unexpected failure),
@emph{UPASS} (unexpected success), or @emph{ERROR} (a severe error in the test
case itself).
Specifying @emph{--verbose} to see output for tests with status @emph{PASS}
(success, as expected) and @emph{XFAIL} (failure, as expected). It also
causes a more detailed summary to be displayed.@*
Specifying @emph{--verbose} more than once causes more detail to be displayed.

@item --version
@itemx -V
@cindex @code{-V} (@code{greg} option)
@cindex @code{--version} (@code{greg} option)
@cindex version numbers
Prints out the version numbers of Greg, and Guile, then
exits without running any tests.

@end table


@node Writing tests, Index, Invoking Greg, Top
@chapter Writing tests
@cindex writing tests
@cindex testcase

@subsection types of testsuite

There are three types of situation where Greg may be used as a test
framework -

@itemize @bullet

@item
Embedded testing @*

In this case, you have an application that uses Guile as it's scripting
language - so you have provided an interface between the internals of
your program and the Guile interpreter.

Your testcases can use that interface to test your program directly, and
you run the tests by loading the @emph{Greg} framework and then doing
@emph{(greg-test-run)}

A testsuite for @emph{embedded} use does not normally need @emph{begin.grg}
or @emph{end.grg} since the application to be tested will be running the
tests on itself - so it doesn't need to control child processes.

@item
Library testing @*

When you want to test a library, you need to write a tiny program to
start up the Guile command-line interpreter with the library to be tested
inked in to the program via a via a set of stubs.  The resulting program
can then be used to run tests on the directly, just like normal embedded
testing.

There is a tool called @emph{G-Wrap} (by Chris Lee), which will
generate stubs to import your library functions into Guile.  The home
page of this tool is at @url{http://www.cs.cmu.edu/~chrislee/g-wrap/}

For testing Objective-C libraries, you should use the GNUstep-Guile
interface library (@url{http://www.tiptree.demon.co.uk/gstep}) which
provides a fairly complete interface between the Guile and Objective-C
languages (using the GNU objective-C runtime).

@item
External testing@*

When you want to test an external program, you use @emph{Greg} in much
the same way that you would use @emph{DejaGNU}.  That is - you run the
program to be tested as a separate child process and your test cases
consist of Guile code to send commands to the child process and wait
for responses from it.

The child process is normally started by a @emph{begin.grg} script
using the @emph{(greg-child)} procedure.

@end itemize

@subsection testsuite file layout

A testsuite for a @emph{tool} is a directory containing one or more
test script files and (optionally) @emph{begin.grg} and @emph{end.grg}
files to handle initialisation and cleanup.

Each script file has a @emph{.scm} extension and contains Guile (Scheme)
code, but you do not need to know much about the Guile programming
language to write most tests.

A script file will contain one or more testcases - each of which
constitutes a test of a single well defined feature of the @emph{tool}
that the script is meant to test.  A testcase is always written
using the @emph{greg-testcase} procedure.

@subsection greg-testcase
@cindex greg-testcase

The @emph{greg-testcase} procedure takes three arguments -

@itemize @bullet
@item The assertion@*
This is a string describing the test to be performed.  It should take the
form of an assertion that is expected to hold true.

@item The expected outcome@*
This is a boolean value - @emph{#t} if the test is expected to return
@emph{#t} (ie. the assertion is expected to be proved correct), and
@emph{#f} if the test is expected to return @emph{#f} (ie. the assertion
is expected to be proved to be incorrect).

@item The test itself@*
This is a @emph{thunk} (a Guile procedure that takes no arguments) and is
normally a @emph{lambda expression}.  The return value of this procedure
should be @emph{#t} if the assertion is proved correct, @emph{#f} if it
is proved incorrect.
@end itemize

The Guile programming language permits the @emph{thunk} to return in four
ways -

@itemize @bullet
@item Return the boolean value - @emph{#t}@*
In which case, the test has succeeded, the assertion has proved correct,
and Greg will record either an expected success (PASS) or an unexpected
success (UPASS) depending on the expected outcome passed to
@emph{greg-testcase}.

@item Return the boolean value - @emph{#f}@*
In which case, the test has failed, the assertion has proved incorrect,
and Greg will record either an expected failure (XFAIL) or an unexpected
failure (FAIL) depending on the expected outcome passed to
@emph{greg-testcase}.

@item Return a non-boolean value@*
In which case, the test is unresolved (UNRESOLVED).

@item Throw an exception@*
In which case Greg's behavior depends on the exception thrown -
@itemize @bullet
@item 'pass@*
Greg acts as if the test had returned the boolean @emph{#t}
@item 'fail@*
Greg acts as if the test had returned the boolean @emph{#f}
@item 'unsupported@*
Greg reports this case as unsupported (UNSUPPORTED)
@item 'untested@*
Greg reports this case as untested (UNTESTED)
@item (quit)@*
If the script calls the @emph{(quit)} primitive - an exception is raised.
In this special case, the test is reported as unresolved (UNRESOLVED) and
no further tests are executed.  The testrun is terminated.
@item any other exception@*
Greg reports this case as unresolved (UNRESOLVED)
@end itemize
@end itemize

As there are no other ways in which the @emph{thunk} may be exited, it is
impossible for a testcase to produce a result that doesn't fit into the
framework (unless your testcase manages either to crash Guile or enter an
infinite loop - in which case you won't get @emph{any} output).

The value returned by the @emph{greg-testcase} procedure is a boolean -
@emph{#t} if the test resulted in an expected pass, @emph{#f} otherwise.@*
You can use this return value to make the execution of subsequent testcases 
dependent on the success of an earlier testcase.

@cartouche
@smallexample

;
; A testcase to check an instance of numeric addition
;
(greg-testcase "One plus One is two" #t
(lambda ()
  (eq? (+ 1 1 ) 2)
))

;
;  The above testcase will generate output -
;  `PASS: One plus One is two'
;
@end smallexample
@end cartouche

@subsection Multiple testcases
@cindex multiple testcases

It is normal to have more than one testcase in a file and this
produces no problems - the only thing to watch out for is communicating
information between testcases -

The scope of variables defined in the @emph{thunk} in a @emph{greg-testcase}
procedure call is that @emph{thunk} - the variable will @emph{not} be
visible to the next testcase.

So - to pass information from one testcase to the next it is necessary to
define variables that can be seen in each testcase.  The way to do this
is normally to define these variables at the start of the file and then
use the @emph{set!} procedure within each testcase to set a value for a
variable to be passed to the next testcase.

@cartouche
@smallexample

(define arith-ok #f)

;
; A testcase to check an instance of numeric addition
;
(greg-testcase "One plus One is two" #t
(lambda ()
  (if (eq? (+ 1 1 ) 2)
    (begin (set! arith-ok #t) #t)
    #f)
))

;
; A testcase to check arithmetic - only supported if we have addition.
;
(greg-testcase "X multiplied by 2 is X plus X" #t
(lambda ()
  (if arith-ok
    (eq? (+ 1 1) (* 1 2))
    (throw 'unsupported))
))

@end smallexample
@end cartouche

Of course, if (as above) the only information you want to pass from a testcase
is whether the test succeeded or not, you can use the return value from the
@emph{greg-testcase} procedure directly -

@cartouche
@smallexample

(if
  (greg-testcase "One plus One is two" #t
    (lambda ()
      (eq? (+ 1 1 ) 2)
    )
  )
  (greg-testcase "X multiplied by 2 is X plus X" #t
    (lambda ()
      (eq? (+ 1 1) (* 1 2))
    )
  )
  (greg-dlog "Arithmetic operations not supported\n")
)

@end smallexample
@end cartouche

@subsection External tests
@cindex external tests

When Greg is used to test an external application, you usually want to run
that application as a child process on a pseudo-terminal and handle tests
sending a sequence of commands to the application and reading anticipated
output from the application.


@subsubsection Starting a child process
@cindex starting a child process
@cindex greg-child

Greg provides the @emph{greg-child} procedure to start up a child process
on a pseudo-terminal.  You would usually call this procedure in the
@emph{begin.grg} file in your @emph{tool} directory, but you could call it
at the start of each script to get a new child process for each script.

The @emph{greg-child} procedure expects one argument (the name of
the program to be executed) followed by any number of additional
arguments which are the arguments to be passed to the child process.@*
If the program name does not begin with a slash, Greg will look in the
directory specified in @emph{greg-obj-dir} to find it (by default the
current directory).@*
If you want your normal PATH to be searched for the program, you should
use -@*
@code{(greg-child "/bin/sh" "-c" "foo args")}@*
to get the shell to execute program @emph{foo} with arguments @emph{args}.

The @emph{greg-child} procedure will automatically close down the I/O
channels to any process previously started and wait for that process to
die.  If the old child process is badly behaved and will not die, this
can result in Greg hanging - in this case you may need to explicitly
kill the old child by another method before starting the new child
process (this is one of the uses of the @emph{end.grg} script).

As a special case, you can use an empty string as the program name -
if you do this, another copy of the guile process will be created as
a child and the value returned by @emph{greg-child} in the child process
will be a list containing the single number 0 (in the parent it will be
a list containing the input port, output port and process id of the child).
You can use this information to get the child copy of the process to 
be the program under test.  This is useful for embedded testing where you
want to test the I/O capabilities of the program.

NB. The @emph{greg-child} procedure is implemented on top of the new
primitive @emph{pty-child}.  This primitive is used to create a new child
process on the end of a pseudo-terminal.  Arguments and return values are
as for @emph{greg-child}.

@itemize @bullet
@item
When successfully starting a new program a three item list is returned in the
parent - input port to read from the child, output port to write to the child,
process id of child.
@item
When returning in a child process because the program name was an empty string
a list of one item (zero) is returned.
@item
After a failure to create a child process, an empty list is returned.
@end itemize


@subsubsection Sending to a child process
@cindex sending to a child process
@cindex greg-send

The @emph{greg-send} procedure is provided to send instructions to a
child process.  This procedure takes one or more string arguments and
sends them to the child process (if one exists).

@subsubsection Reading from a child process
@cindex reading from a child process
@cindex greg-recv

The @emph{greg-recv} macro is used to read data from a child process.
This procedure actually provides a simple front-end to the @emph{expect}
module.  You can use the @emph{expect} module facilities directly if you
want more control than is offered by @emph{greg-recv}.

The @emph{greg-recv} macro expects one or more lists as arguments -
each list containing a string (a pattern to match)
and a result to return on a successful match.  The value returned by
@emph{greg-recv} is the result for the pattern actually matched.@*
If no pattern is matched within the timeout period then an empty list
is returned (unless you use @emph{(set! expect-timeout-proc xxx)} to
override Gregs timeout handler.@*
If no pattern is matched before an end-of-file is read, then an empty list
is returned (unless you use @emph{(set! expect-eof-proc xxx)} to
override Gregs end-of-file handler.

@node Index, , Writing tests, Top
@unnumbered Index

@printindex cp

@contents

@bye

