Damir Murat created GROOVY-10878:
------------------------------------
Summary: Improve JaCoCo's branch code coverage of a Groovy assert
statement
Key: GROOVY-10878
URL: https://issues.apache.org/jira/browse/GROOVY-10878
Project: Groovy
Issue Type: Improvement
Affects Versions: 4.0.6
Reporter: Damir Murat
At the moment, there is no way to have full branch coverage for Groovy
{{assert}} statements. In a larger project, this is very distractive when
trying to find the pieces of actual logic that should be better covered with
tests. I believe a slight change in {{assert}} statement code generation can
significantly improve the situation.
JaCoCo has long-standing issues with covering calls of methods that throw
exceptions.
When such methods are called inside of, {{if/else}} branches, for example, the
result is
partial coverage reported for those branches.
However, there is a JaCoCo idiom
([https://github.com/jacoco/jacoco/issues/370#issuecomment-267854179|http://example.com])
that can be used to avoid uncovered code in those cases. The basic idea is to
create and return an exception from a called method and throw that exception
from a caller, like in:
{code:java}
void fail() {
throw create();
}
RuntimeException create() {
return new RuntimeException();
}
{code}
How this relates to the Groovy {{assert}} statement? For example, for a simple
{{assert}} statement like
{code:java}
assert firstName != null
{code}
Groovy generates something like
{code:java}
ValueRecorder var1 = new ValueRecorder();
try {
String var10000 = this.firstName;
var1.record(var10000, 8);
var1.record(var10000, 8);
if (var10000 != null) {
var1.clear();
} else {
ScriptBytecodeAdapter.assertFailed(AssertionRenderer.render("assert
firstName != null", var1), (Object)null);
}
} catch (Throwable var3) {
var1.clear();
throw var3;
}
{code}
The problem with generated code is a
{code:java}
ScriptBytecodeAdapter.assertFailed(AssertionRenderer.render("assert firstName
!= null", var1), (Object)null);
{code}
method call. Inside that method, an exception is created and thrown. Since
JaCoCo cannot cover that line completely, the branch
{code:java}
if (var10000 != null)
{code}
will be reported as partially covered.
To avoid those issues, {{ScriptBytecodeAdapter.assertFailed()}} can be adapted
(or a new method can be introduced like in the example below) to return the
exception instead of throwing it. And then, the calling generated code can
throw that returned exception:
{code:java}
try {
...
if (var10000 != null) {
...
} else {
Throwable throwable =
ScriptBytecodeAdapter.createAssertionError(AssertionRenderer.render("assert
firstName != null", var1), (Object)null);
throw throwable
}
} catch (Throwable var3) {
...
}
{code}
I have a small project demonstrating the issue and a possible solution here:
[https://github.com/dmurat/groovy-assert-jacoco-coverage-problem|http://example.com]
Tnx
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