diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/Bug246129.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/Bug246129.java
index 09cbafbb0c1..03b42ad1377 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/Bug246129.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/Bug246129.java
@@ -32,7 +32,9 @@ import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.core.model.IPathEntry;
 import org.eclipse.cdt.core.model.ITranslationUnit;
 import org.eclipse.cdt.core.testplugin.CProjectHelper;
+import org.eclipse.cdt.core.testplugin.ResourceHelper;
 import org.eclipse.cdt.core.testplugin.TestScannerProvider;
+import org.eclipse.cdt.core.testplugin.util.BaseTestCase5;
 import org.eclipse.cdt.internal.core.pdom.indexer.IndexerPreferences;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IFolder;
@@ -147,7 +149,9 @@ public class Bug246129 extends IndexTestBase {
 		fExternalIncludeFolder.delete();
 
 		fTmpDir.delete();
-
+		ResourceHelper.cleanUp(getName());
+		CProjectHelper.delete(fProject);
+		BaseTestCase5.assertWorkspaceIsEmpty();
 		super.tearDown();
 	}
 
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexSearchTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexSearchTest.java
index e67be0df2ce..c89160033c9 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexSearchTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexSearchTest.java
@@ -32,6 +32,7 @@ import org.eclipse.cdt.core.index.IIndexBinding;
 import org.eclipse.cdt.core.index.IndexFilter;
 import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.core.testplugin.CProjectHelper;
+import org.eclipse.cdt.core.testplugin.util.BaseTestCase5;
 import org.eclipse.cdt.internal.core.index.CIndex;
 import org.eclipse.cdt.internal.core.pdom.PDOM;
 import org.eclipse.cdt.internal.core.pdom.dom.PDOMBinding;
@@ -68,14 +69,12 @@ public class IndexSearchTest extends IndexTestBase {
 	@Override
 	public void tearDown() throws Exception {
 		fIndex.releaseReadLock();
+		CProjectHelper.delete(fProject);
+
+		BaseTestCase5.assertWorkspaceIsEmpty();
 		super.tearDown();
 	}
 
-	public void deleteProject() {
-		if (fProject != null) {
-			CProjectHelper.delete(fProject);
-		}
-	}
 
 	private void checkIsClass(IIndexBinding binding) {
 		assertTrue(binding instanceof ICPPClassType);
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTestBase.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTestBase.java
index 84c535968d4..25028a3432d 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTestBase.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTestBase.java
@@ -41,7 +41,7 @@ public abstract class IndexTestBase extends BaseTestCase {
 		workspace.run(new IWorkspaceRunnable() {
 			@Override
 			public void run(IProgressMonitor monitor) throws CoreException {
-				String name = "IndexTest_" + System.currentTimeMillis();
+				String name = "IndexTest_" + getName() + "_" + System.currentTimeMillis();
 				if (useCpp) {
 					result[0] = CProjectHelper.createCCProject(name, null, IPDOMManager.ID_NO_INDEXER);
 				} else {
diff --git a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase5.java b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase5.java
index 36cad3fdf69..2cd4278fc83 100644
--- a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase5.java
+++ b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase5.java
@@ -24,7 +24,10 @@ import static org.junit.jupiter.api.Assertions.fail;
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Deque;
+import java.util.List;
 
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IValue;
@@ -39,12 +42,14 @@ import org.eclipse.cdt.internal.core.pdom.CModelListener;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IResource;
+import org.eclipse.core.resources.IWorkspaceRoot;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.MultiStatus;
 import org.eclipse.core.runtime.NullProgressMonitor;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.jobs.Job;
+import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Tag;
@@ -140,6 +145,33 @@ public abstract class BaseTestCase5 {
 		BaseTestCase5.removeLeftOverProjects();
 	}
 
+	/**
+	 * assert that the virtual workspace is empty and that
+	 * there are no files left on disk in the workspace directory
+	 * this latter one is important because a new project can
+	 * be created with the same named and then those old files
+	 * will end up part of the project unexpectedly
+	 */
+	@AfterAll
+	public static void assertWorkspaceIsEmpty() throws CoreException {
+		IWorkspaceRoot root = ResourcesPlugin.getWorkspace().getRoot();
+		// use lists because error messages are nicer
+		assertEquals(List.of(), Arrays.asList(root.members()));
+
+		File workspaceFile = root.getLocation().toFile();
+
+		// Special permission for an empty "tmp" directory so
+		// that ResourceHelper.createTemporaryFolder() does not
+		// need to be reworked
+		File file = new File(workspaceFile, "tmp");
+		List<String> permitted = new ArrayList<>(List.of(".metadata"));
+		if (file.isDirectory()) {
+			assertEquals(List.of(), Arrays.asList(file.list()));
+			permitted.add("tmp");
+		}
+		assertEquals(List.of(), Arrays.asList(workspaceFile.list((dir, name) -> !permitted.contains(name))));
+	}
+
 	protected void deleteOnTearDown(File file) {
 		filesToDeleteOnTearDown.add(file);
 	}