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build/test/test_system.html
Vladimir Prus 64d934d4a0 Test system tweaks.
* test/TestCmd.py: Cause the names of preserved directories to be
        printed.
    * test/test_system.html: Document "PRESERVE*" environmental variables
       and "pass_test"/"fail_test" methods.


[SVN r14389]
2002-07-10 07:31:24 +00:00

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<p><a href="../../../index.htm"><img class="banner" height="86" width=
"277" alt="C++ Boost" src="../../../c++boost.gif"></a></p>
<h1>A testing system for Boost.Build<br class="clear">
</h1>
<hr>
<dl class="page-index">
<dt><a href="#sec-intro">Introduction and examples</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#sec-intro-changing">Changing the working
directory</a></dt>
<dt><a href="#sec-intro-examining">Examining the working directory
and changing it</a></dt>
<dt><a href="#sec-intro-results">Test result</a></dt>
</dl>
</dd>
<dt><a href="#sec-reference">Reference documentation</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#method-__init__">Method __init__</a></dt>
<dt><a href="#method-set_tree">Method <tt>set_tree</tt></a></dt>
<dt><a href="#method-write">Method <tt>write</tt></a></dt>
<dt><a href="#method-copy">Method <tt>copy</tt></a></dt>
<dt><a href="#method-touch">Method <tt>touch</tt></a></dt>
<dt><a href="#method-run_build_system">Method
<tt>run_build_system</tt></a></dt>
<dt><a href="#method-read">Method <tt>read</tt></a></dt>
<dt><a href="#method-read_and_strip">Method
<tt>read_and_strip</tt></a></dt>
<dt><a href="#methods-expectations">Methods for declaring
expectations</a></dt>
<dt><a href="#methods-ignoring">Methods for ignoring
changes</a></dt>
<dt><a href="#methods-result">Methods for explicitly specifying
results</a></dt>
<dt><a href="#class-list">Helper class <tt>List</tt></a></dt>
</dl>
</dd>
</dl>
<hr>
<h2><a name="sec-intro">Introduction and examples</a></h2>
<p>The testing system for Boost.Build is derived from the
<tt>TestCmd</tt> Python module used for testing the <a href=
"http://www.scons.org">Scons</a> build tools. The changes are very few,
and I hope that some of them may be adopted by <tt>TestCmd</tt> in
future.</p>
<p>Unfortunately, there are not documentation for <tt>TestCmd</tt>, apart
from the comments in code, so the most essential base methods will be
described here.</p>
<p>The basic steps of testing a build system behaviour are:</p>
<ol>
<li>Setting the initial working directory state</li>
<li>
Running the build system and checking:
<ol>
<li>generated output,</li>
<li>changes made to the working directory,</li>
<li>new content of the working directory.</li>
</ol>
</li>
<li>Adding, removing or touching files, or changing their content and
then repeating the previous step, until satisfied.</li>
</ol>
<p>Prior to using the test system, make sure you have checked out the
Boost CVS and have successfully build Jam -- which means that
<tt>bjam</tt> executable is available.</p>
<p>For example, suppose that you've placed under
<tt>tools/build/test</tt> a file <tt>test1.py</tt> and a subdirectory
<tt>test1</tt> with files <tt>foo.cpp</tt>, <tt>Jamfile</tt> and
<tt>Jamrules</tt>. A definition of function <tt>main</tt> is the only
content of <tt>foo.cpp</tt>, <tt>Jamfile</tt> builds an executable
<tt>foo</tt> from <tt>foo.cpp</tt> and <tt>Jamrules</tt> is empty.
Finally, <tt>test1.py</tt> contains:</p>
<pre class="code">
from BoostBuild import Tester, List
# Create a temporary working directory
t = Tester()
# Make content of the working directory equal to the content of the 'test1' directory.
t.set_tree('test1')
# Invoke 'bjam -sTOOLS=borland' and record which changes were made
t.run_build_system("-sTOOLS=borland")
# First, create a list of three pathnames
file_list = List("bin/foo/borland/debug/runtime-link-dynamic/foo") * List(".exe .obj")
# Second, assert that those files were added as result of the last build system invocation.
t.expect_addition(file_list)
# Invoke the build system once again
t.run_build_system("clean")
# Check if the files added previously were removed.
t.expect_removal(t.mul("bin/foo/borland/debug/runtime-link-dynamic/foo", [".exe", ".obj", ".tds"]))
</pre>
<p>This is all needed for a minimal test (and to find a bug in the
borland toolset!). Running the <tt>test1.py</tt> gives the following
output:</p>
<pre class="output">
File bin/foo/borland/debug/runtime-link-dynamic/foo.tds not removed as expected
FAILED test of D:\MyDocu~1\Work\build\boost-build\boost-build -d0
at line 144 of TestBoostBuild.py (expect_removal)
from line 12 of test1.py
</pre>
<p>Overview of the most important methods of class
<tt>TestBoostBuild</tt> follows.</p>
<h3><a name="sec-intro-changing">Changing the working directory</a></h3>
<p>The class <tt>TestBoostBuild</tt> creates a temporary directory in its
constructor and changes to that directory. It can be modified by calling
these methods:</p>
<ul>
<li><tt>set_tree</tt> -- sets the content of the working directory to
be equal to the content of the specified directory.</li>
<li><tt>write</tt> -- sets the content of file in a working
directory</li>
<li><tt>touch</tt> -- changes the modification times of a file</li>
</ul>
<h3><a name="sec-intro-examining">Examining the working directory and
changing it</a></h3>
<p>The method <tt>read</tt>, inherited from the <tt>TestCmd</tt> class,
can be used to read any file in the working directory and check its
content. <tt>TestBoostBuild</tt> adds another method for tracking
changes. Whenever build system is run (via <tt>run_build_system</tt>),
the state of working dir before and after running is recorded. In
addition, difference between the two states -- i.e. lists of files that
were added, removed, modified or touched -- is stored in two member
variables, <tt>tree_difference</tt> and
<tt>unexpected_difference</tt>.</p>
<p>After than, the test author may specify that some change is expected,
for example, by calling <tt>expect_addition("foo")</tt>. This call will
check if the file was indeed added, and if so, will remove its name from
the list of added files in <tt>unexpected_difference</tt>. Likewise, it's
possible to specify that some changes are not interesting, for example a
call <tt>ignore("*.obj")</tt> will just remove every files with ".obj"
extension from <tt>unexpected_difference</tt>.</p>
<p>When test has finished with expectations and ignoring, the member
<tt>unexpected_difference</tt> will contain the list of all changes not
yet accounted for. It is possible to assure that this list is empty by
calling <tt>expect_nothing_more</tt> member function.</p>
<h3><a name="sec-intro-results">Test result</a></h3>
<p>Any of the <tt>expect*</tt> methods below will fail the test if the
expectation is not met. It is also possible to perform manually arbitrary
test and explicitly cause the test to either pass or fail. Ordinary
filesystem functions can be used to work with the directory tree. Methods
<tt>pass_test</tt> and <tt>fail_test</tt> are used to explicitly give the
test outcome.</p>
<p>Typically, after test termination, the working directory is erased. If
is possible to prevent it by setting environmental variables
<tt>PRESERVE</tt>, <tt>PRESERVE_PASS</tt> and <tt>PRESERVE_FAIL</tt>.
Non-zero value of the first makes the working directory preserved in all
cases, while the other variables apply only to specific outcomes. When a
directory is preserved, its name will be printed to the standard
output.</p>
<h2><a name="sec-reference">Reference documentation</a></h2>
<p>The test system is composed of class <tt>Tester</tt>, derived form
<tt>TestCmd.TestCmd</tt>, and helper class <tt>List</tt>. The methods of
<tt>Tester</tt>, and the class <tt>List</tt> are described below.</p>
<p>The documentation frequently refer to filename. In all cases, files
are specified in unix style: a sequence of components, separated by "/".
This is true on all platforms. In some contexts, a list of files is
allowed. In that case any object with sequence interface is allowed.</p>
<h3><a name="method-__init__">Method <tt>__init__(self, arguments='',
executable='bjam')</tt></a></h3>
<p><b>Effects:</b></p>
<ol>
<li>Remembers the current working directory in member
<tt>original_workdir</tt>.</li>
<li>Determines the location of executable (<code>bjam</code> by
default) and build system files, assuming that the current directory is
<tt>tools/build/test</tt>. Formulates jam invocation command, which
will include explicit setting for <tt>BOOST_BUILD_PATH</tt> variable
and arguments passed to this methods, if any. This command will be used
by subsequent invocation of <a href=
"#method-run_build_system"><tt>run_build_system</tt></a>. Finally,
initializes the base class.</li>
<li>Changes current working dir to the temporary working directory
created by the base constructor.</li>
</ol>
<h3><a name="method-set_tree">Method <tt>set_tree(self,
tree_location)</tt></a></h3>
<p><b>Effects:</b></p>
<p>Replaces the content of the current working directory with the content
of directory at <tt>tree_location</tt>. If <tt>tree_location</tt> is not
absolute pathname, it will be treated as relative to
<tt>self.original_workdir</tt>. This methods also explicitly makes the
copied files writeable.</p>
<h3><a name="method-write">Method <tt>write(self, name,
content)</tt></a></h3>
<p><b>Effects:</b></p>
<p>Writes the specified content to the file given by <tt>name</tt> under
the temporary working directory. If the file already exists, it is
overwritten. Any required directories are automatically created.</p>
<h3><a name="method-copy">Method <tt>copy(self, src, dst)</tt></a></h3>
<p><b>Effects:</b></p>
<p>Equvivalent to <tt>self.write(self.read(src), dst)</tt>.</p>
<h3><a name="method-touch">Method <tt>touch(self, names)</tt></a></h3>
<p><b>Effects:</b></p>
<p>Sets the access and modification times for all files in <tt>names</tt>
to the current time. All the elements in <tt>names</tt> should be
relative paths.</p>
<h3><a name="method-run_build_system">Method <tt>run_build_system(self,
subdir='', extra_args='', stdout=None, stderr='', status=0,
**kw)</tt></a></h3>
<p><b>Effects:</b></p>
<ol>
<li>Stores the state of the working directory in
<tt>self.previous_tree</tt>.</li>
<li>Changes to <tt>subdir</tt>, if it is specified. If it is not
absolute path, it is relative to the working dir.</li>
<li>Invokes the <tt>bjam</tt> executable, passing <tt>extra_args</tt>
to it. The binary should be located under
<tt>&lt;test_invocation_dir&gt;/../jam_src/bin.&lt;platform&gt;</tt>.
This is to make sure tests use the version of jam build from CVS.</li>
<li>Compares the stdout, stderr and exit status of build system
invocation with values to appropriate parameters, if they are not
<tt>None</tt>. If any difference is found, the test fails.</li>
<li>
<p>Stores the new state of the working directory in
<tt>self.tree</tt>. Computes the difference between previous and
current trees and store them in variables
<tt>self.tree_difference</tt> and
<tt>self.unexpected_difference</tt>.</p>
<p>Both variables are instances of class
<tt>tree.Trees_different</tt>, which have four attributes:
<tt>added_files</tt>, <tt>removed_files</tt>, <tt>modified_files</tt>
and <tt>touched_files</tt>. Each is a list of strings.</p>
</li>
</ol>
<h3><a name="method-read">Method <tt>read(self, name)</tt></a></h3>
<p><b>Effects:</b></p>
<p>Read the specified file and returns it content. Raises an exception is
the file is absent.</p>
<h3><a name="method-read_and_strip">Method <tt>read_and_strip(self,
name)</tt></a></h3>
<p><b>Effects:</b></p>
<p>Read the specified file and returns it content, after removing
trailing whitespace from every line. Raises an exception is the file is
absent.</p>
<p><b>Rationale:</b></p>
<p>Althought this method is questionable, there are a lot of cases when
jam or shells it uses insert spaces. It seems that introducing this
method is much simpler than dealing with all those cases.</p>
<h3><a name="methods-expectations">Methods for declaring
expectations</a></h3>
<p>Accordingly to the number of changes kinds that are detected, there
are four methods that specify that test author expects a specific change
to occur. They check <tt>self.unexpected_difference</tt>, and if the
change is present there, it is removed. Otherwise, test fails.</p>
<p>Each method accepts a list of names. Those names are always
unix-style, even on other systems.</p>
<p><b>Note:</b> The <tt>List</tt> helper class might be useful to create
lists of names.</p>
<p><b>Note:</b> The file content can be examined using
<tt>TestCmd.read</tt> function.</p>
<p>The members are:</p>
<ul>
<li>expect_addition</li>
<li>expect_removal</li>
<li>expect_modification</li>
<li>expect_touch</li>
<li>expect_nothing</li>
</ul>
<p>There's also a member <tt>expect_nothing_more</tt>, which checks that
all the changes are either expected or ignored, in other words that
<tt>unexpected_difference</tt> is empty by now.</p>
<p>Lastly, there's a method to compare file content with expected
content:</p>
<tt>expect_content(self, name, content, exact=0)</tt>
<p>The method fails the test if the content of file identified by 'name'
is different from 'content'. If 'exact' is true, the file content is used
as-is, otherwise, two transformations are applied:</p>
<ul>
<li>The <tt>read_and_strip</tt> method is used to read the file, which
removes trailing whitespace</li>
<li>Each backslash in the file content is converted to forward
slash.</li>
</ul>
<h3><a name="methods-ignoring">Methods for ignoring changes</a></h3>
<p>There are five methods which ignore changes made to the working tree.
They silently remove elements from <tt>self.unexpected_difference</tt>,
and don't generate error if element is not found. They accept shell style
wildcard.</p>
<p>The following methods correspond to four kinds of changes:</p>
<ul>
<li>ignore_addition(self, wildcard)</li>
<li>ignore_removal(self, wildcard)</li>
<li>ignore_modification(self, wildcard)</li>
<li>ignore_touch(self, wilcard)</li>
</ul>
<p>The method <tt>ignore(self, wildcard)</tt> ignores all the changes
made to files that match a wildcard.</p>
<h3><a name="methods-result">Methods for explicitly specifying
results</a></h3>
<h4>Method <tt>pass_test(self, condition=1)</tt></h4>
<div class="attention">
At this moment, the method should not be used.
</div>
<h4>Method <tt>fail_test(self, condition=1)</tt></h4>
<p><b>Effects:</b> Cause the test to fail if <tt>condition</tt> is
true.</p>
<h3><a name="class-list">Helper class <tt>List</tt></a></h3>
The class has sequence interface and two additional methods.
<h4>Method <tt>__init__(self, string)</tt></h4>
<p><b>Effects:</b> Splits the string on unescaped spaces and tabs. The
split components can further be retrieved using standard sequence
access.</p>
<h4>Method <tt>__mul__(self, other)</tt></h4>
<p><b>Effects:</b> Returns an <tt>List</tt> instance, which elements are
all possible concatenations of two string, first of which is from
<tt>self</tt>, and second of which is from <tt>other</tt>.</p>
<p>The class also defines <tt>__str__</tt> and <tt>__repr__</tt> methods.
Finally, there's <tt>__coerce__</tt> method which allows to convert
strings to instances of <tt>List</tt>.</p>
<p><b>Example:</b></p>
<pre>
l = "a b" * List("c d")
for e in l:
print e
</pre>
<p>will output</p>
<pre>
ac
ad
bc
bd
</pre>
<hr>
<p class="revision">Last modified: May 5, 2002</p>
<p>&copy; Copyright Vladimir Prus 2002. Permission to copy, use, modify,
sell and distribute this document is granted provided this copyright
notice appears in all copies. This document is provided ``as is'' without
express or implied warranty, and with no claim as to its suitability for
any purpose.</p>
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