feat: keep flakiness in table and user server-side pagination for flakiness overview

[meryemefe]

Motivation

After deploying Flakiness Overview feature to test environment, I realized that calculating flakiness score on the fly causes critical performance issue, even Java Heap Out of Memory error. Therefore, it is essential to keep flakiness score in the database and using server side pagination in flakiness overview implementation.

Description

• Created test_case_flakiness table which keeps flakiness_score, default_branch_failure_rate, combined_failure_rate.
• test_case_flakiness table is updated in TestResultProcessor after updating test_case_statistics.
• Added pagination to getFlakyTestsOverview service, which returns results in pages and sorted by flakiness_score.
• In the frontend, Flakiness Overview page is updated with new API call and made compatible with server-side pagination.
• Flakiness computation process is optimized with map usage and bulk get queries on database.

Testing Instructions

Prerequisites:

• Access to a Helios with at least one repository with tests with different flakiness scores.

Flow:

1. Log in to Helios as a Developer
2. Currently test_case_flakiness is empty. Run a test workflow to calculate flaky tests.
3. Navigate to the Flakiness Overview page for a repository
4. Verify:
   4.1. Table loads successfully.
   4.2. Search and severity filter still update the displayed page.
   4.3. Pagination controls behave consistently with server-side results.

Screenshots

Checklist

General

• PR description explains the purpose and changes. (f.e. following the 'Conventional Commits')
• Changes have been tested locally.
• Screenshots have been attached.

Server

• Code is performant and follows best practices
• I documented the Java code using JavaDoc style.

Client

• I documented the TypeScript code using JSDoc style.
• I added multiple screenshots/screencasts of my UI changes.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ -0.15% (target: -1.00%)	✅ 62.83%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (437fcaa)	8387	2715	32.37%
Head commit (de80e11)	8445 (+58)	2721 (+6)	32.22% (-0.15%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#920)	191	120	62.83%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[Copilot]

Pull request overview

This PR addresses performance issues in the Flakiness Overview by persisting flakiness metrics in a dedicated DB table and switching the overview endpoint + UI to server-side pagination/filtering/sorting.

Changes:

• Add test_case_flakiness table + JPA entity/repository and recompute/update it after test statistics updates.
• Update flaky tests overview endpoint/service to query the precomputed table with pagination + filters and return filteredCount.
• Update Angular Flakiness Overview page to use lazy server-side pagination/filtering/sorting and align OpenAPI-generated client types.

Reviewed changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
server/application-server/src/main/resources/db/migration/V38__add_test_case_flakiness.sql	Adds new table + index to persist flakiness metrics efficiently.
server/application-server/src/main/java/de/tum/cit/aet/helios/tests/TestCaseStatisticsService.java	Implements flakiness persistence + paged overview query from the new table.
server/application-server/src/main/java/de/tum/cit/aet/helios/tests/TestResultProcessor.java	Triggers recomputation/persistence after statistics updates.
server/application-server/src/main/java/de/tum/cit/aet/helios/tests/TestResultController.java	Extends /api/tests/flaky with pagination/filter/search params.
server/application-server/src/main/java/de/tum/cit/aet/helios/tests/FlakyTestOverviewDto.java	Adjusts DTO to match server-side paging (filteredCount) and new storage model.
server/application-server/openapi.yaml	Documents new query params and updated response shape.
client/src/app/pages/flaky-tests-overview/*	Moves Flakiness Overview table to server-side lazy loading and updates UI accordingly.
server/client tests & OpenAPI generated files	Updates tests and generated client types for the API change.

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[mertilginoglu]

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[chatgpt-codex-connector]

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