Spy on onProcessFileChangesException (#120421)

server/src/test/java/org/elasticsearch/reservedstate/service/FileSettingsServiceTests.java

@@ -214,6 +214,9 @@ public void testInitialFileError() throws Exception {
         // wait until the watcher thread has started, and it has discovered the file
         assertTrue(latch.await(20, TimeUnit.SECONDS));
 
+        // Note: the name "processFileOnServiceStart" is a bit misleading because it is not
+        // referring to fileSettingsService.start(). Rather, it is referring to the initialization
+        // of the watcher thread itself, which occurs asynchronously when clusterChanged is first called.
         verify(fileSettingsService, times(1)).processFileOnServiceStart();
         verify(controller, times(1)).process(any(), any(XContentParser.class), eq(ReservedStateVersionCheck.HIGHER_OR_SAME_VERSION), any());
         // assert we never notified any listeners of successful application of file based settings
@@ -312,7 +315,7 @@ public void testInvalidJSON() throws Exception {
             } finally {
                 awaitOrBust(fileChangeBarrier);
             }
-        }).when(fileSettingsService).processFileChanges();
+        }).when(fileSettingsService).onProcessFileChangesException(any());
         writeTestFile(fileSettingsService.watchedFile(), "test_invalid_JSON");
         awaitOrBust(fileChangeBarrier);
 
@@ -326,10 +329,6 @@ public void testInvalidJSON() throws Exception {
             argThat(e -> unwrapException(e) instanceof XContentParseException)
         );
 
-        // Note: the name "processFileOnServiceStart" is a bit misleading because it is not
-        // referring to fileSettingsService.start(). Rather, it is referring to the initialization
-        // of the watcher thread itself, which occurs asynchronously when clusterChanged is first called.
-
         assertEquals(YELLOW, healthIndicatorService.calculate(false, null).status());
         verify(healthIndicatorService, Mockito.atLeast(1)).failureOccurred(contains(XContentParseException.class.getName()));
     }