diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d7ec86fcf408..52a80ad7394df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 ## v1.42.0
 
 - [core] fixed logger level propagation when log config file changes at runtime [#12566](https://github.com/eclipse-theia/theia/pull/12566) - Contributed on behalf of STMicroelectronics
+- [vscode] stub TestController invalidateTestResults [#12944](https://github.com/eclipse-theia/theia/pull/12944) - Contributed by STMicroelectronics
 - [vsx-registry] added a hint to extension fetching ENOTFOUND errors [#12858](https://github.com/eclipse-theia/theia/pull/12858) - Contributed by STMicroelectronics
 
 ## v1.41.0 - 08/31/2023
diff --git a/packages/plugin-ext/src/plugin/plugin-context.ts b/packages/plugin-ext/src/plugin/plugin-context.ts
index 0e73c0d34f9df..0f44efee200fa 100644
--- a/packages/plugin-ext/src/plugin/plugin-context.ts
+++ b/packages/plugin-ext/src/plugin/plugin-context.ts
@@ -232,7 +232,8 @@ import {
     createRunProfile,
     createTestRun,
     testItemCollection,
-    createTestItem
+    createTestItem,
+    invalidateTestResults
 } from './stubs/tests-api';
 import { TimelineExtImpl } from './timeline';
 import { ThemingExtImpl } from './theming';
@@ -1010,6 +1011,7 @@ export function createAPIFactory(
                     createRunProfile,
                     createTestRun,
                     createTestItem,
+                    invalidateTestResults,
                     dispose: () => undefined,
                 };
             },
diff --git a/packages/plugin-ext/src/plugin/stubs/tests-api.ts b/packages/plugin-ext/src/plugin/stubs/tests-api.ts
index 79a896de20562..16b06b2ec5597 100644
--- a/packages/plugin-ext/src/plugin/stubs/tests-api.ts
+++ b/packages/plugin-ext/src/plugin/stubs/tests-api.ts
@@ -96,3 +96,7 @@ export const createTestItem = (
     range: undefined,
     error: undefined,
 });
+
+export const invalidateTestResults = (
+    items?: theia.TestItem | readonly theia.TestItem[]
+): void => undefined;
diff --git a/packages/plugin/src/theia.d.ts b/packages/plugin/src/theia.d.ts
index 59c8d7374cdc4..0a2e5130eb1a2 100644
--- a/packages/plugin/src/theia.d.ts
+++ b/packages/plugin/src/theia.d.ts
@@ -15980,6 +15980,25 @@ export module '@theia/plugin' {
          */
         createTestItem(id: string, label: string, uri?: Uri): TestItem;
 
+        /**
+         * Marks an item's results as being outdated. This is commonly called when
+         * code or configuration changes and previous results should no longer
+         * be considered relevant. The same logic used to mark results as outdated
+         * may be used to drive {@link TestRunRequest.continuous continuous test runs}.
+         *
+         * If an item is passed to this method, test results for the item and all of
+         * its children will be marked as outdated. If no item is passed, then all
+         * test owned by the TestController will be marked as outdated.
+         *
+         * Any test runs started before the moment this method is called, including
+         * runs which may still be ongoing, will be marked as outdated and deprioritized
+         * in the editor's UI.
+         *
+         * @param item Item to mark as outdated. If undefined, all the controller's items are marked outdated.
+         * @stubbed
+         */
+        invalidateTestResults(items?: TestItem | readonly TestItem[]): void;
+
         /**
          * Unregisters the test controller, disposing of its associated tests
          * and unpersisted results.