An incomplete shard snapshot will prevent a shard from moving away from a node (see `SnapshotInProgressAllocationDecider`). That means that when a shard snapshot completes it may become possible to perform some shard movements that previously were not possible, so we should trigger a reroute to start those movements. AFAICT we do not trigger such a reroute today.
test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java
if (enableWarningsCheck()) {
            this.threadContext = new ThreadContext(Settings.EMPTY);
            HeaderWarning.setThreadContext(threadContext);
        }
    }
    /**
     * Whether or not we check after each test whether it has left warnings behind. That happens if any deprecated feature or syntax
     * was used by the test and the test didn't assert on it using {@link #assertWarnings(String...)}.
     */
    protected boolean enableWarningsCheck() {
        return true;
    }
    @After
    public final void after() throws Exception {
        checkStaticState();
        
        
        
        
        if (threadContext != null) {
            ensureNoWarnings();
            HeaderWarning.removeThreadContext(threadContext);
            threadContext = null;
        }
        ensureAllSearchContextsReleased();
        ensureCheckIndexPassed();
        logger.info("{}after test", getTestParamsForLogging());
    }
    private String getTestParamsForLogging() {
        String name = getTestName();