apache/beam

Code coverage numbers are not accurate

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#18194 opened on Jun 3, 2022

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Description

We've started adding Java Code Coverage numbers to PRs using the jacoco gradle plugin.

When we ran this in Maven, we got very low coverage reported for things like the Java SDK core. This was likely because we test the bulk of the SDK not in the SDK module, but in fact in the DirectRunner and other similar modules.

This is the still the case in gradle. So we'll need to make sure to watch for it.

This is a good "random improvement" issue for anyone to pick up.

Imported from Jira BEAM-1399. Original Jira may contain additional context. Reported by: dhalperi.

Contributor guide

Tech stack
java
Domain
testingci cd
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Gradle build systemJaCoCo coverage plugin
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The issue states that code coverage numbers are inaccurate because tests for the SDK module are run in other modules like DirectRunner. To fix this, one needs to review the Gradle configuration for JaCoCo aggregation across modules. Check the jacoco plugin setup in the root build.gradle and how module specific test tasks are configured. Consider using JaCoCo's merge or report aggregation tasks to combine coverage data from multiple subprojects. Look at the existing Gradle build scripts (e.g., `build.gradle` in sdk/java/core and DirectRunner) to understand the test source sets and coverage exclusions.