Using Coverage Contexts

Clover defines a Context as a part of source code that matches a specified structure or pattern. Contexts are either pre-defined or user-defined at instrumentation time. Each context must have a unique name. At report time, you can specify which contexts you would like to exclude in the coverage report.

Block Contexts

Block Contexts are pre-defined by Clover. They represent 'block' syntatic constructs in the Java language. A full list of supported Block Contexts is shown below.

Method Contexts

A Method Context represents the set of methods whose signature matches a given pattern. Clover provides several pre-defined method contexts:

A method signature includes all annotations, modifiers (public, static, final etc), the return type, the method name, parameter types and names, the throws clause and exceptions.

Note When matching method signatures against context regexps, whitespace is normalised and comments are ignored.

You can define your own method contexts via the <methodContext> sub-element of <clover-setup>, or via the configuration panel of your Clover IDE Plugin.

Note Contexts are matched against your source at instrumentation-time. This means you need to re-instrument your code after defining a new context.

Statement Contexts

A Statement Context represents the set of statements that match a given pattern. For example, you might want to set up a statement context to allow you to filter out 'noisy' statements (such as logging calls) by defining a statement context regexp .*LOG\.debug.*.

Using Context Filters

Note This section describes using context filters with Ant. For details of using filters with the IDE plugins, see the individual documentation for the plugin.

Filtering catch blocks

In some cases you may not be interested in the coverage of statements inside catch blocks. To filter them, you can use Clover's predefined catch context to exclude statements inside catch blocks from a coverage report:

<clover-report>
       <current outfile="clover_html">
         <format type="html" filter="catch"/>
       </current>
   </clover-report>

This generates a source-level HTML report that excludes coverage from statements inside catch blocks.

Filtering logging statements

To remove logging statements for coverage reports, you will need to define one or more statement contexts that match logging statements in your source:

<clover-setup ...>
       <statementContext name="log" regexp="^LOG\..*"/>
       <statementContext name="iflog" regexp="^if \(LOG\.is.*"/>
       <methodContext name="main" regexp="public static void main\(String args\[\]\).*"/>
     ...
   </clover-setup>

This defines two statement contexts and one method context. The first matches statements that start with 'LOG.' while the second matches statements that start with  'if (LOG.', which is designed to match conditional logging statements such as:

if (LOG.isDebugEnabled()) {
      // do some expensive debug logging
   }

The second matches all 'main' methods that have a String Array named 'args' in the constructor:

public static void main(String args[]) throws Exception

After defining these contexts, you now need to re-compile with Clover and then re-run your tests. You can then generate a report that excludes logging statements:

<clover-report>
       <current outfile="clover_html" title="My Coverage">
         <format type="html" filter="log,iflog"/>
       </current>
   </clover-report>

This generates a source-level HTML report that excludes coverage from logging statements.