.. role:: ref(emphasis)

.. _futhark-test(1):

============
futhark-test
============

SYNOPSIS
========

futhark test [options...] infiles...

DESCRIPTION
===========

This tool is used to test Futhark programs based on input/output
datasets.  If a directory is given, all contained files with a
``.fut`` extension are considered.

A Futhark test program is an ordinary Futhark program, with at least
one test block describing input/output test cases and possibly other
options.  A test block consists of commented-out text with the
following overall format::

  description
  ==
  cases...

The ``description`` is an arbitrary (and possibly multiline)
human-readable explanation of the test program.  It is separated from
the test cases by a line containing just ``==``.  Any comment starting
at the beginning of the line, and containing a line consisting of just
``==``, will be considered a test block.  The format of a test case is
as follows::

  [tags { tags... }]
  [entry: names...]
  [compiled|nobench|random] input ({ values... } | @ filename)
  output { values... } | auto output | error: regex

If ``compiled`` is present before the ``input`` keyword, this test
case will never be passed to the interpreter.  This is useful for test
cases that are annoyingly slow to interpret.  The ``nobench`` keyword
is for data sets that are too small to be worth benchmarking, and only
has meaning to :ref:`futhark-bench(1)`.

If ``input`` is preceded by ``random``, the text between the curly
braces must consist of a sequence of Futhark types, including sizes in
the case of arrays.  When ``futhark test`` is run, a file located in a
``data/`` subdirectory, containing values of the indicated types and
shapes is, automatically constructed with ``futhark-dataset``.  Apart
from sizes, integer constants (with or without type suffix) are also
permitted.

If ``input`` is followed by an ``@`` and a file name (which must not
contain any whitespace) instead of curly braces, values will be read
from the indicated file.  This is recommended for large data sets.
This notation cannot be used with ``random`` input.

After the ``input`` block, the expected result of the test case is
written as either ``output`` followed by another block of values, or
an expected run-time error, in which a regular expression can be used
to specify the exact error message expected.  If no regular expression
is given, any error message is accepted.  If neither ``output`` nor
``error`` is given, the program will be expected to execute
succesfully, but its output will not be validated.

If ``output`` is preceded by ``auto`` (as in ``auto output``), the
expected values are automatically generated by compiling the program
with ``futhark-c`` and recording its result for the given input (which
must not fail).  This is usually only useful for testing or
benchmarking alternative compilers, and not for testing the
correctness of Futhark programs.

Alternatively, instead of input-output pairs, the test cases can
simply be a description of an expected compile time type error::

  error: regex

This is used to test the type checker.

By default, both the interpreter and compiler is run on all test cases
(except those that have specified ``compiled``), although this can be
changed with command-line options to ``futhark test``.

Tuple syntax is not supported when specifying input and output values.
Instead, you can write an N-tuple as its constituent N values.  Beware
of syntax errors in the values - the errors reported by
``futhark test`` are very poor.

An optional tags specification is permitted in the first test block.
This section can contain arbitrary tags that classify the benchmark::

  tags { names... }

Tag are sequences of alphanumeric characters, dashes, and underscores,
with each tag seperated by whitespace.  Any program with the
``disable`` tag is ignored by ``futhark test``.

Another optional directive is ``entry``, which specifies the entry
point to be used for testing.  This is useful for writing programs
that test libraries with multiple entry points.  Multiple entry points
can be specified on the same line by separating them with space, and
they will all be tested with the same input/output pairs.  The
``entry`` directive affects subsequent input-output pairs in the same
comment block, and may only be present immediately preceding these
input-output pairs.  If no ``entry`` is given, ``main`` is assumed.
See below for an example.

For many usage examples, see the ``tests`` directory in the
Futhark source directory.  A simple example can be found in
``EXAMPLES`` below.

OPTIONS
=======

--backend=program

  The backend used when compiling Futhark programs (without leading
  ``futhark``, e.g. just ``opencl``).

-c
  Only run compiled code - do not run any interpreters.

-C
  Compile the programs, but do not run them.


--concurrency=NUM

  The number of tests to run concurrently.  Defaults to the number of
  (hyper-)cores available.

--exclude=tag

  Do not run test cases that contain the given tag.  Cases marked with
  "disable" are ignored by default.

-i
  Only interpret - do not run any compilers.

-t
  Type-check the programs, but do not run them.

--futhark=program

  The program used to perform operations (eg. compilation).  Defaults
  to the binary running ``futhark test`` itself.

--no-terminal
  Print each result on a line by itself, without line buffering.

--no-tuning

  Do not look for tuning files.

--pass-option=opt

  Pass an option to benchmark programs that are being run.  For
  example, we might want to run OpenCL programs on a specific device::

    futhark test prog.fut --backend=opencl --pass-option=-dHawaii

--pass-compiler-option=opt

  Pass an extra option to the compiler when compiling the programs.

--runner=program

  If set to a non-empty string, compiled programs are not run
  directly, but instead the indicated *program* is run with its first
  argument being the path to the compiled Futhark program.  This is
  useful for compilation targets that cannot be executed directly (as
  with :ref:`futhark-csharp(1)`), or when you wish to run the program
  on a remote machine.

--tuning=EXTENSION

  For each program being run, look for a tuning file with this
  extension, which is suffixed to the name of the program.  For
  example, given ``--tuning=tuning`` (the default), the program
  ``foo.fut`` will be passed the tuning file ``foo.fut.tuning`` if it
  exists.

EXAMPLES
========

The following program tests simple indexing and bounds checking::

  -- Test simple indexing of an array.
  -- ==
  -- tags { firsttag secondtag }
  -- input { [4,3,2,1] 1 }
  -- output { 3 }
  -- input { [4,3,2,1] 5 }
  -- error: Assertion.*failed

  let main (a: []i32) (i: i32): i32 =
    a[i]

The following program contains two entry points, both of which are
tested::

  let add(x: i32, y: i32): i32 = x + y

  -- Test the add1 function.
  -- ==
  -- entry: add1
  -- input { 1 } output { 2 }

  entry add1 (x: i32): i32 = add x 1

  -- Test the sub1 function.
  -- ==
  -- entry: sub1
  -- input { 1 } output { 0 }

  entry sub1 (x: i32): i32 = add x (-1)

The following program contains an entry point that is tested with
randomly generated data::

  -- ==
  -- random input { [100]i32 [100]i32 } auto output
  -- random input { [1000]i32 [1000]i32 } auto output

  let main xs ys = i32.product (map2 (*) xs ys)


SEE ALSO
========

:ref:`futhark-bench(1)`, :ref:`futhark-repl(1)`