Add filter for bytecode generated by Kotlin serialization compiler plugin #1885

Godin · 2025-04-29T21:45:32Z

leveretka

Looks good! Thanks for looking into the issue.

I was thinking if we could somehow prevent such regression as it's tough thinking in advance of other possible compiler plugins and their combinations. On the other hand, serialization plugin is a pretty big one and we now have a test for it.

leveretka · 2025-09-24T09:54:30Z

org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/KotlinSerializableFilter.java

+			nextIs(Opcodes.ARETURN);
+			return cursor != null
+					&& getStaticInstruction.name.equals("INSTANCE")
+					&& (lineNumberInstruction instanceof LineNumberNode)


Sadly we can't use pattern matching on instanceOf here (Java 14) :(

ajeihala · 2025-10-08T11:56:31Z

Thanks a lot @Godin for taking care of this MR as Kotlinx Serialization caused a lot of troubles for me with synthetic methods and coverage.

I use a snapshot Jacoco version and today it broke for my project perhaps due to this commit (or another about ASM update). Please take a look if it's something relevant for a fix:

...
Caused by: java.io.IOException: Error while analyzing BillingAddressFieldType$Companion.class with JaCoCo 0.8.14.202510071157/0981128.
        at org.jacoco.core.analysis.Analyzer.analyzerError(Analyzer.java:163)
        at org.jacoco.core.analysis.Analyzer.analyzeClass(Analyzer.java:135)
        at org.jacoco.core.analysis.Analyzer.analyzeClass(Analyzer.java:158)
        at org.jacoco.core.analysis.Analyzer.analyzeAll(Analyzer.java:195)
        at org.jacoco.ant.ReportTask.createBundle(ReportTask.java:573)
        at org.jacoco.ant.ReportTask.createReport(ReportTask.java:545)
        at org.jacoco.ant.ReportTask.execute(ReportTask.java:496)
        ... 155 more
Caused by: java.lang.NullPointerException: Cannot invoke "org.objectweb.asm.tree.AbstractInsnNode.getPrevious()" because "this.cursor" is null
        at org.jacoco.core.internal.analysis.filter.KotlinSerializableFilter$Matcher.match(KotlinSerializableFilter.java:79)
        at org.jacoco.core.internal.analysis.filter.KotlinSerializableFilter.filter(KotlinSerializableFilter.java:44)
        at org.jacoco.core.internal.analysis.filter.FilterSet.filter(FilterSet.java:31)
        at org.jacoco.core.internal.analysis.filter.Filters$1.filter(Filters.java:45)
        at org.jacoco.core.internal.analysis.ClassAnalyzer.addMethodCoverage(ClassAnalyzer.java:131)
        at org.jacoco.core.internal.analysis.ClassAnalyzer.access$100(ClassAnalyzer.java:38)
        at org.jacoco.core.internal.analysis.ClassAnalyzer$1.accept(ClassAnalyzer.java:115)
        at org.jacoco.core.internal.flow.ClassProbesAdapter$2.visitEnd(ClassProbesAdapter.java:91)
        at org.objectweb.asm.ClassReader.readMethod(ClassReader.java:1516)
        at org.objectweb.asm.ClassReader.accept(ClassReader.java:745)
        at org.objectweb.asm.ClassReader.accept(ClassReader.java:425)
        at org.jacoco.core.analysis.Analyzer.analyzeClass(Analyzer.java:117)
        at org.jacoco.core.analysis.Analyzer.analyzeClass(Analyzer.java:133)

The class it complains about BillingAddressFieldType$Companion.class has an empty companion object declared without any body/fields (just companion object).

Godin · 2025-10-08T12:31:14Z

@ajeihala first of all thank you for testing snapshot version and for the report ❤
while there is already another report #1969 with the same stack trace
your example is different and

empty companion object declared without any body/fields (just companion object)

like

@Serializable
class EmptyCompanion {
    companion object
}

does not seem to be enough to trigger NPE, so could you please provide source code of your BillingAddressFieldType and/or class files BillingAddressFieldType.class and BillingAddressFieldType$Companion.class entirely to make sure that we won't miss some corner-case again?

ajeihala · 2025-10-08T12:40:25Z

Perhaps the enum class makes the difference.

With this

@Serializable
enum class EmptyCompanion {
    @SerialName("TEST")
    TEST;
    companion object
}

it fails too with Error while analyzing EmptyCompanion$Companion.class with JaCoCo 0.8.14.202510071157/0981128 and the same Cannot invoke "org.objectweb.asm.tree.AbstractInsnNode.getPrevious()" because "this.cursor" is null.

Godin · 2025-10-08T13:03:11Z

@ajeihala thanks!

Perhaps the enum class makes the difference.

yes - it is
fix for #1969 will handle both,
so we will communicate updates in it but not here - you can subscribe to it

Godin added the component: core.filters label Apr 29, 2025

Godin self-assigned this Apr 29, 2025

Godin added this to Filtering Apr 29, 2025

github-project-automation bot moved this to Awaiting triage in Filtering Apr 29, 2025

Godin added the language: Kotlin label Apr 29, 2025

Godin linked an issue Apr 29, 2025 that may be closed by this pull request

Code coverage incorrect for Kotlin data classes with kotlinx.serialization in JaCoCo 0.8.13 #1855

Closed

Godin moved this from Awaiting triage to In Progress in Filtering Apr 29, 2025

(WIP) add validation test

a1b4f51

Godin force-pushed the kotlin_serialization branch from 62da77b to a1b4f51 Compare April 29, 2025 22:50

(WIP) add unit tests

5353fdd

Godin force-pushed the kotlin_serialization branch from 0abbc62 to 5353fdd Compare August 25, 2025 20:10

(WIP) add filter

104ee4b

Godin added this to the 0.8.14 milestone Aug 25, 2025

Godin and others added 2 commits August 25, 2025 23:18

Merge branch 'master' into kotlin_serialization

a2101cb

(WIP) update changelog

bf49e9a

Godin marked this pull request as ready for review August 25, 2025 21:35

Godin requested a review from leveretka August 25, 2025 21:35

leveretka approved these changes Sep 24, 2025

View reviewed changes

Godin added 2 commits October 7, 2025 22:55

Merge branch 'master'

5882aea

(WIP) NFC: adjust tests after merge of Kotlin version upgrade

fc2b85e

Godin enabled auto-merge (squash) October 7, 2025 22:25

Godin merged commit d07bc6b into jacoco:master Oct 7, 2025
36 checks passed

Godin deleted the kotlin_serialization branch October 7, 2025 22:33

github-project-automation bot moved this from In Progress to Done in Filtering Oct 7, 2025

This was referenced Oct 8, 2025

Fix NPE in KotlinSerializableFilter #1970

Merged

KotlinSerializationFilter does not work with sealed classes annotated with @Serializable and crashes JaCoCo report generation #1969

Closed

Godin mentioned this pull request Oct 10, 2025

KotlinSerializableFilter should filter more methods #1971

Merged

marcin-arciszewski-gds mentioned this pull request Oct 17, 2025

feat: upgrade jacoco to 0.8.14 govuk-one-login/mobile-android-pipelines#191

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Add filter for bytecode generated by Kotlin serialization compiler plugin #1885

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