}
        };
    Function<Object, String> backward = toStringFunction();

    Converter<String, Number> converter = Converter.<String, Number>from(forward, backward);

    assertNull(converter.convert(null));
    assertNull(converter.reverse().convert(null));

    assertEquals((Integer) 5, converter.convert("5"));
    assertEquals("5", converter.reverse().convert(5));
  }

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

        ViewHelper.ActionHook actionHook = new ViewHelper.ActionHook();

        try {
            assertNull(actionHook.godHandPrologue(null, runtime -> null));
            assertNull(actionHook.godHandMonologue(null, runtime -> null));
            actionHook.godHandEpilogue(null, runtime -> {});
            assertNull(actionHook.hookBefore(null, runtime -> null));
            actionHook.hookFinally(null, runtime -> {});

        assertNull(transformer.getThumbnailUrl(responseData, getDocument(data)));

        data = "<img src=\"http://example/foo.jpg\" width=\"x\" height=\"x\">";
        assertNull(transformer.getThumbnailUrl(responseData, getDocument(data)));

        data = "<img src=\"http://example/foo.jpg\" width=\"10\" height=\"100\">";
        assertNull(transformer.getThumbnailUrl(responseData, getDocument(data)));

        value = "";
        assertEquals("", dataStore.convertValue(Constants.DEFAULT_SCRIPT, value, paramMap));

        value = " ";
        assertNull(dataStore.convertValue(Constants.DEFAULT_SCRIPT, value, paramMap));
    }

          inv.containsValue(reversed.getValue()));
      /*
       * TODO(cpovirk): This is a bit stronger than super.expectMissing(), which permits a <key,
       * someOtherValue> pair.
       */
      assertNull(
          "Inverse should not return a mapping for key " + reversed.getKey(),
          inv.get(reversed.getKey()));
    }
  }

    for (int i = 0; i < getNumElements(); i++) {
      assertTrue(
          "toArray(overSizedE[]) should contain element " + expectedSubArray[i],
          subArray.contains(expectedSubArray[i]));
    }
    assertNull(
        "The array element immediately following the end of the collection should be nulled",
        array[getNumElements()]);
    // array[getNumElements() + 1] might or might not have been nulled
  }

        ComponentUtil.setFessConfig(null);
        super.tearDown();
    }

    public void test_evaluate() {
        final Map<String, Object> params = new HashMap<>();
        assertNull(groovyEngine.evaluate("", params));
        assertEquals("", groovyEngine.evaluate("return ''", params));
        assertEquals(1, groovyEngine.evaluate("return 1", params));

        params.put("test", "123");

  public void testCreateParentDirs_root() throws IOException {
    File file = root();
    assertNull(file.getParentFile());
    assertNull(file.getCanonicalFile().getParentFile());
    Files.createParentDirs(file);
  }

  public void testCreateParentDirs_relativePath() throws IOException {
    File file = file("nonexistent.file");
    assertNull(file.getParentFile());
    assertNotNull(file.getCanonicalFile().getParentFile());

    }

    public void test_nullHandling() {
        // Test with null ParseException
        QueryParseException queryParseException = new QueryParseException(null);
        assertNotNull(queryParseException);
        assertNull(queryParseException.getCause());
        // getMessage() may return null when constructed with null
        // This is expected behavior for exceptions with null cause
    }

    public void test_nestedCause() {