1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2026 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ///////////////////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle.utils;
21
22 import static com.google.common.truth.Truth.assertWithMessage;
23 import static com.puppycrawl.tools.checkstyle.internal.utils.TestUtil.getExpectedThrowable;
24 import static com.puppycrawl.tools.checkstyle.internal.utils.TestUtil.isUtilsClassHasPrivateConstructor;
25
26 import org.junit.jupiter.api.Test;
27
28 public class NullUtilTest {
29
30 @Test
31 public void testIsProperUtilsClass() throws ReflectiveOperationException {
32 assertWithMessage("Constructor is not private")
33 .that(isUtilsClassHasPrivateConstructor(NullUtil.class))
34 .isTrue();
35 }
36
37 @Test
38 public void testNotNullWithNonNullValue() {
39 final String value = "test";
40 final String result = NullUtil.notNull(value);
41 assertWithMessage("Result should equal input value")
42 .that(result)
43 .isEqualTo(value);
44 }
45
46 @Test
47 public void testNotNullWithNullValue() {
48 final AssertionError ex = getExpectedThrowable(AssertionError.class, () -> {
49 NullUtil.notNull(null);
50 });
51 assertWithMessage("Error should indicate misuse")
52 .that(ex)
53 .hasMessageThat()
54 .contains("Misuse of notNull");
55 }
56 }