LLVM Testing Infrastructure Guide
=================================
-Written by John T. Criswell, Daniel Dunbar, Reid Spencer, and Tanya
-Lattner
-
.. contents::
:local:
; RUN: diff %t1 %t2
As with a Unix shell, the RUN lines permit pipelines and I/O
-redirection to be used. However, the usage is slightly different than
-for Bash. In general, it's useful to read the code of other tests to figure out
-what you can use in yours. The major differences are:
-
-- You can't do ``2>&1``. That will cause :program:`lit` to write to a file
- named ``&1``. Usually this is done to get stderr to go through a pipe. You
- can do that with ``|&`` so replace this idiom:
- ``... 2>&1 | grep`` with ``... |& grep``
-- You can only redirect to a file, not to another descriptor and not
- from a here document.
+redirection to be used.
There are some quoting rules that you must pay attention to when writing
your RUN lines. In general nothing needs to be quoted. :program:`lit` won't
strip off any quote characters so they will get passed to the invoked program.
-For example:
+To avoid this use curly braces to tell :program:`lit` that it should treat
+everything enclosed as one value.
-.. code-block:: bash
+In general, you should strive to keep your RUN lines as simple as possible,
+using them only to run tools that generate textual output you can then examine.
+The recommended way to examine output to figure out if the test passes is using
+the :doc:`FileCheck tool <CommandGuide/FileCheck>`. *[The usage of grep in RUN
+lines is deprecated - please do not send or commit patches that use it.]*
- ... | grep 'find this string'
+Fragile tests
+-------------
-This will fail because the ``'`` characters are passed to ``grep``. This would
-make ``grep`` to look for ``'find`` in the files ``this`` and
-``string'``. To avoid this use curly braces to tell :program:`lit` that it
-should treat everything enclosed as one value. So our example would become:
+It is easy to write a fragile test that would fail spuriously if the tool being
+tested outputs a full path to the input file. For example, :program:`opt` by
+default outputs a ``ModuleID``:
-.. code-block:: bash
+.. code-block:: console
- ... | grep {find this string}
+ $ cat example.ll
+ define i32 @main() nounwind {
+ ret i32 0
+ }
-In general, you should strive to keep your RUN lines as simple as possible,
-using them only to run tools that generate the output you can then examine. The
-recommended way to examine output to figure out if the test passes it using the
-:doc:`FileCheck tool <CommandGuide/FileCheck>`. The usage of ``grep`` in RUN
-lines is discouraged.
-
-The FileCheck utility
----------------------
-
-A powerful feature of the RUN lines is that it allows any arbitrary
-commands to be executed as part of the test harness. While standard
-(portable) unix tools like ``grep`` work fine on run lines, as you see
-above, there are a lot of caveats due to interaction with shell syntax,
-and we want to make sure the run lines are portable to a wide range of
-systems. Another major problem is that ``grep`` is not very good at checking
-to verify that the output of a tools contains a series of different
-output in a specific order. The :program:`FileCheck` tool was designed to
-help with these problems.
-
-:program:`FileCheck` is designed to read a file to check from standard input,
-and the set of things to verify from a file specified as a command line
-argument. :program:`FileCheck` is described in :doc:`the FileCheck man page
-<CommandGuide/FileCheck>`.
+ $ opt -S /path/to/example.ll
+ ; ModuleID = '/path/to/example.ll'
+
+ define i32 @main() nounwind {
+ ret i32 0
+ }
+
+``ModuleID`` can unexpetedly match against ``CHECK`` lines. For example:
+
+.. code-block:: llvm
+
+ ; RUN: opt -S %s | FileCheck
+
+ define i32 @main() nounwind {
+ ; CHECK-NOT: load
+ ret i32 0
+ }
+
+This test will fail if placed into a ``download`` directory.
+
+To make your tests robust, always use ``opt ... < %s`` in the RUN line.
+:program:`opt` does not output a ``ModuleID`` when input comes from stdin.
Variables and substitutions
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projects / oota-llvm.git / blobdiff