Migrate org.eclipse.core.filebuffers.tests to JUnit 5

[vogella]

Migrates the tests in from JUnit 4 to JUnit 5.

Changes include:

• Updating to depend on JUnit 5 packages.
• Converting imports and annotations in test classes (e.g., , , ).
• Updating assertions to use .
• Converting to use .

Tests verified locally.

[eclipse-platform-bot]

This pull request changes some projects for the first time in this development cycle.
Therefore the following files need a version increment:

tests/org.eclipse.core.filebuffers.tests/META-INF/MANIFEST.MF

An additional commit containing all the necessary changes was pushed to the top of this PR's branch. To obtain these changes (for example if you want to push more changes) either fetch from your fork or apply the git patch.

Git patch

From dac6016c78f838280ae745073f7153bae5cf0613 Mon Sep 17 00:00:00 2001
From: Eclipse Platform Bot <platform-bot@eclipse.org>
Date: Mon, 12 Jan 2026 10:21:22 +0000
Subject: [PATCH] Version bump(s) for 4.39 stream


diff --git a/tests/org.eclipse.core.filebuffers.tests/META-INF/MANIFEST.MF b/tests/org.eclipse.core.filebuffers.tests/META-INF/MANIFEST.MF
index 923620b068..534cf3b960 100644
--- a/tests/org.eclipse.core.filebuffers.tests/META-INF/MANIFEST.MF
+++ b/tests/org.eclipse.core.filebuffers.tests/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Plugin.name
 Bundle-SymbolicName: org.eclipse.core.filebuffers.tests;singleton:=true
-Bundle-Version: 3.13.600.qualifier
+Bundle-Version: 3.13.700.qualifier
 Bundle-Activator: org.eclipse.core.filebuffers.tests.FileBuffersTestPlugin
 Bundle-ActivationPolicy: lazy
 Bundle-Vendor: %Plugin.providerName
-- 
2.52.0

Further information are available in Common Build Issues - Missing version increments.

[github-actions]

Test Results

 3 018 files  ±0   3 018 suites  ±0   2h 12m 48s ⏱️ - 5m 7s
 8 270 tests ±0   8 022 ✅ +1  248 💤 ±0  0 ❌  - 1 
23 634 runs  ±0  22 843 ✅ +1  791 💤 ±0  0 ❌  - 1 

Results for commit d5e2c06. ± Comparison against base commit 647256d.

♻️ This comment has been updated with latest results.

[vogella]

Feedback applied