@Test
    public void testMDC() {
        MDC.put("k", "v");
        assertNotNull(MDC.get("k"));
        assertEquals("v", MDC.get("k"));

        MDC.remove("k");
        assertNull(MDC.get("k"));

        MDC.put("k1", "v1");
        assertEquals("v1", MDC.get("k1"));
        MDC.clear();
        assertNull(MDC.get("k1"));

        try {
            MDC.put(null, "x");
            fail("null keys are invalid");
        } catch (IllegalArgumentException e) {
        }
    }
Test whether invoking the SLF4J API causes problems or not.

@author Ceki Gulcu
slf4j-jdk14/src/test/java/org/slf4j/jul/InvocationTest.java