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Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]1<?xml version="1.0" encoding="UTF-8" ?>
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13 <a href="../index.html" class="el_report">JaCoCo</a> &gt;
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15 <span class="el_source">FAQ</span>
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18
19<h1>FAQ</h1>
20
21<p>
22 This is a compilation of questions that have been asked by JaCoCo users
23 before.
24</p>
25
26<h3>Does JaCoCo have a plug-in for [Eclipse|Netbeans|Whatever...]?</h3>
27<p>
28 See <a href="integrations.html">this list</a> for current integrations with
29 various tools.
Marc R. Hoffmann08db74b2013-01-16 07:58:13 +0100[diff] [blame]30</p>
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]31
Marc R. Hoffmann2cd6b612014-03-12 22:36:32 +0100[diff] [blame]32<h3>What Java versions are supported by JaCoCo?</h3>
33<p>
34 JaCoCo supports Java class files from version 1.0 to 1.7. However the minimum
35 JRE version required by the JaCoCo runtime (e.g. the agent) and the JaCoCo
36 tools is 1.5. Also note that class files under test from version 1.6 and above
37 have to contain valid stackmap frames.
38</p>
39
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]40<h3>Why do I get the error "Can't add different class with same name"?</h3>
41<p>
42 For coverage report generation all classes within a group must have unique
43 names. You get this error during report generation if JaCoCo is supplied with
44 multiple different class files with the same name. To fix this remove those
45 duplicate classes or create separate reports or report groups for each version.
Marc R. Hoffmann08db74b2013-01-16 07:58:13 +0100[diff] [blame]46</p>
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]47
Marc R. Hoffmannf6787ed2012-11-13 23:03:55 +0100[diff] [blame]48<h3>Code with exceptions shows no coverage. Why?</h3>
49<p>
50 JaCoCo determines code execution with so called probes. Probes are inserted
51 into the control flow at certain positions. Code is considered as executed
52 when a subsequent probe has been executed. In case of exceptions such a
53 sequence of instructions is aborted somewhere in the middle and not marked as
Marc R. Hoffmann2cd6b612014-03-12 22:36:32 +0100[diff] [blame]54 executed.
Marc R. Hoffmannf6787ed2012-11-13 23:03:55 +0100[diff] [blame]55</p>
56
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]57<h3>Why does the coverage report not show line coverage figures?</h3>
58<p>
Marc R. Hoffmann9a7379b2012-09-21 21:48:35 +0200[diff] [blame]59 JaCoCo is based on class files analysis. To calculate line coverage class
60 files must contain line number attributes. For this your code must be compiled
61 with debug information.
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]62</p>
63
Marc R. Hoffmannfa48e772014-03-13 12:31:30 +0100[diff] [blame^]64<h3>Why does the coverage report not show highlighted source code?</h3>
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]65<p>
66 Make sure the following prerequisites are fulfilled to get source code
67 highlighting in JaCoCo coverage reports:
68</p>
69<ul>
70 <li>Class files must be compiled with debug information to contain line numbers.</li>
71 <li>Source files must be properly supplied at report generation time. I.e.
72 specified source folders must be the direct parent of the folders that
73 define the Java packages.</li>
74</ul>
75
76<h3>Why does a class show as not covered although it has been executed?</h3>
77<p>
78 First make sure execution data has been collected. For this select the
79 <i>Sessions</i> link on the top right corner of the HTML report and check
80 whether the class in question is listed. If it is listed but not linked the
81 class at execution time is a different class file. Make sure you're using the
Marc R. Hoffmann9a7379b2012-09-21 21:48:35 +0200[diff] [blame]82 exact same class file at runtime as for report generation. Note that some
83 tools (e.g. EJB containers, mocking frameworks) might modify your class files
Marc R. Hoffmannfa48e772014-03-13 12:31:30 +0100[diff] [blame^]84 at runtime. Please see the chapter about <a href="classids.html"> class
85 ids</a> for a detailed discussion.
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]86</p>
87
88<h3>Why are Java interface types not shown in the coverage reports?</h3>
89<p>
90 Java interface methods do not contain code, therefore code coverage cannot
91 be evaluated. Indeed code coverage is recorded for the implementation classes.
92 The same applies to abstract methods in abstract classes.
93</p>
94
Marc R. Hoffmann9a7379b2012-09-21 21:48:35 +0200[diff] [blame]95<h3>Can I collect coverage information without stopping the JVM?</h3>
96<p>
97 The JaCoCo <a href="agent.html">agent</a> can be configured for remote control
98 via TCP/IP sockets. This allows to collect execution data at any point in time
99 from a running JVM. The <a href="ant.html#dump"><code>dump</code></a> Ant task
100 can be used to request dumps. The remote control feature also allows you to
101 reset execution data.
102</p>
103
Marc R. Hoffmann08db74b2013-01-16 07:58:13 +0100[diff] [blame]104<h3>My code uses reflection. Why does it fail when I execute it with JaCoCo?</h3>
105<p>
106 To collect execution data JaCoCo instruments the classes under test which adds
107 two members to the classes: A private static field <code>$jacocoData</code>
108 and a private static method <code>$jacocoInit()</code>. Both members are
109 marked as synthetic.
110</p>
111<p>
112 Please change your code to ignore synthetic members. This is a good practice
113 anyways as also the Java compiler creates synthetic members in certain
114 situation.
115</p>
116
Marc R. Hoffmann0b8331b2012-09-19 20:45:37 +0200[diff] [blame]117</div>
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