@Test
    public void testDowngradeType() {
        assertEquals(SAFE_DOWNGRADE, FeatureCommand.downgradeType(
            new Namespace(singletonMap("unsafe", Boolean.FALSE))));
        assertEquals(UNSAFE_DOWNGRADE, FeatureCommand.downgradeType(
            new Namespace(singletonMap("unsafe", Boolean.TRUE))));
        assertEquals(SAFE_DOWNGRADE, FeatureCommand.downgradeType(new Namespace(emptyMap())));
    }
Unit test of {@link FeatureCommand} tool.
tools/src/test/java/org/apache/kafka/tools/FeatureCommandTest.java