[jira] [Closed] (GROOVY-10878) Improve JaCoCo's branch code coverage of a Groovy assert statement

["Paul King (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GROOVY-10878?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul King closed GROOVY-10878.
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> 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
>            Assignee: Eric Milles
>            Priority: Major
>             Fix For: 4.0.7
>
>         Attachments: screenshot-1.png, screenshot-2.png
>
>
> 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|https://github.com/jacoco/jacoco/issues/370#issuecomment-267854179]) 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|https://github.com/dmurat/groovy-assert-jacoco-coverage-problem|]
> Tnx



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