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-rw-r--r--lib/common_test/doc/src/cover_chapter.xml87
1 files changed, 86 insertions, 1 deletions
diff --git a/lib/common_test/doc/src/cover_chapter.xml b/lib/common_test/doc/src/cover_chapter.xml
index b2e64bfff0..4fa92d5583 100644
--- a/lib/common_test/doc/src/cover_chapter.xml
+++ b/lib/common_test/doc/src/cover_chapter.xml
@@ -108,8 +108,8 @@
specifications</seealso>).</p>
</section>
+ <marker id="cover_stop"></marker>
<section>
- <marker id="cover_stop"></marker>
<title>Stopping the cover tool when tests are completed</title>
<p>By default the Cover tool is automatically stopped when the
tests are completed. This causes the original (non cover
@@ -175,6 +175,11 @@
%% Specific modules to exclude in cover.
{excl_mods, Mods}.
+
+ %% Cross cover compilation
+ %% Tag = atom(), an identifier for a test run
+ %% Mod = [atom()], modules to compile for accumulated analysis
+ {cross,[{Tag,Mods}]}.
</pre>
<p>The <c>incl_dirs_r</c> and <c>excl_dirs_r</c> terms tell Common
@@ -190,6 +195,81 @@
specification file for Common Test).</p>
</section>
+ <marker id="cross_cover"/>
+ <section>
+ <title>Cross cover analysis</title>
+ <p>The cross cover mechanism allows cover analysis of modules
+ across multiple tests. It is useful if some code, e.g. a library
+ module, is used by many different tests and the accumulated cover
+ result is desirable.</p>
+
+ <p>This can of course also be achieved in a more customized way by
+ using the <c>export</c> parameter in the cover specification and
+ analysing the result off line, but the cross cover mechanism is a
+ build in solution which also provides the logging.</p>
+
+ <p>The mechanism is easiest explained via an example:</p>
+
+ <p>Let's say that there are two systems, <c>s1</c> and <c>s2</c>,
+ which are tested in separate test runs. System <c>s1</c> contains
+ a library module <c>m1</c> which is tested by the <c>s1</c> test
+ run and is included in <c>s1</c>'s cover specification:</p>
+
+<code type="none">
+s1.cover:
+ {incl_mods,[m1]}.</code>
+
+ <p>When analysing code coverage, the result for <c>m1</c> can be
+ seen in the cover log in the <c>s1</c> test result.</p>
+
+ <p>Now, let's imagine that since <c>m1</c> is a library module, it
+ is also used quite a bit by system <c>s2</c>. The <c>s2</c> test
+ run does not specifically test <c>m1</c>, but it might still be
+ interesting to see which parts of <c>m1</c> is actually covered by
+ the <c>s2</c> tests. To do this, <c>m1</c> could be included also
+ in <c>s2</c>'s cover specification:</p>
+
+<code type="none">
+s2.cover:
+ {incl_mods,[m1]}.</code>
+
+ <p>This would give an entry for <c>m1</c> also in the cover log
+ for the <c>s2</c> test run. The problem is that this would only
+ reflect the coverage by <c>s2</c> tests, not the accumulated
+ result over <c>s1</c> and <c>s2</c>. And this is where the cross
+ cover mechanism comes in handy.</p>
+
+ <p>If instead the cover specification for <c>s2</c> was like
+ this:</p>
+
+<code type="none">
+s2.cover:
+ {cross,[{s1,[m1]}]}.</code>
+
+ <p>then <c>m1</c> would be cover compiled in the <c>s2</c> test
+ run, but not shown in the coverage log. Instead, if
+ <c>ct_cover:cross_cover_analyse/2</c> is called after both
+ <c>s1</c> and <c>s2</c> test runs are completed, the accumulated
+ result for <c>m1</c> would be available in the cross cover log for
+ the <c>s1</c> test run.</p>
+
+ <p>The call to the analyse function must be like this:</p>
+
+<code type="none">
+ct_cover:cross_cover_analyse(Level, [{s1,S1LogDir},{s2,S2LogDir}]).</code>
+
+ <p>where <c>S1LogDir</c> and <c>S2LogDir</c> are the directories
+ named <c>&lt;TestName&gt;.logs</c> for each test respectively.</p>
+
+ <p>Note the tags <c>s1</c> and <c>s2</c> which are used in the
+ cover specification file and in the call to
+ <c>ct_cover:cross_cover_analyse/2</c>. The point of these are only
+ to map the modules specified in the cover specification to the log
+ directory specified in the call to the analyse function. The name
+ of the tag has no meaning beyond this.</p>
+
+ </section>
+
<section>
<title>Logging</title>
<p>To view the result of a code coverage test, follow the
@@ -197,6 +277,11 @@
takes you to the code coverage overview page. If you have
successfully performed a detailed coverage analysis, you
find links to each individual module coverage page here.</p>
+
+ <p>If cross cover analysis has been performed, and there are
+ accumulated coverage results for the current test, then the -
+ "Coverdata collected over all tests" link will take you to these
+ results.</p>
</section>
</chapter>