In this article, we will learn about assertFalse() static method which belongs to JUnit 5 org.junit.jupiter.api.Assertions Class. Note that in JUnit 5 all JUnit 4 assertion methods are moved to org.junit.jupiter.api.Assertions class.
There are many overloaded version of assertFalse() methods present in org.junit.jupiter.api.Assertions class.
Let me list out tools and technologies that I have used to develop JUnit 5 assertFalse Example.
Tools and Technologies Used
- Eclipse photon (only this eclipse version supports JUnit 5)
- Maven
- JUnit 5
- JDK 8 or later
assertFalse() method asserts that a condition is false. If it isn't it throws an AssertionError without a message.
assertFalse() Method Example
In this example, first we will create a complex logic containsWhitespace() method and then we will test this method using JUnit 5 assertFalse method.
public static boolean containsWhitespace(final CharSequence seq) {
if (seq == null || seq.length() == 0) {
return false;
}
final int strLen = seq.length();
for (int i = 0; i < strLen; i++) {
if (Character.isWhitespace(seq.charAt(i))) {
return true;
}
}
return false;
}
Let's write a JUnit test for the above method with different scenarios:
@Test
public void testContainsWhitespace() {
assertFalse(containsWhitespace(null));
assertFalse(containsWhitespace(""));
assertFalse(containsWhitespace("a"));
assertFalse(containsWhitespace("abc"));
assertTrue(containsWhitespace(" "));
assertTrue(containsWhitespace(" a"));
assertTrue(containsWhitespace("abc "));
assertTrue(containsWhitespace("a b"));
assertTrue(containsWhitespace("a b"));
}
Complete Program for Reference
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import org.junit.jupiter.api.Test;
public class JUnit5AssertFalseExample {
public static boolean containsWhitespace(final CharSequence seq) {
if (seq == null || seq.length() == 0) {
return false;
}
final int strLen = seq.length();
for (int i = 0; i < strLen; i++) {
if (Character.isWhitespace(seq.charAt(i))) {
return true;
}
}
return false;
}
@Test
public void testContainsWhitespace() {
assertFalse(containsWhitespace(null));
assertFalse(containsWhitespace(""));
assertFalse(containsWhitespace("a"));
assertFalse(containsWhitespace("abc"));
assertTrue(containsWhitespace(" "));
assertTrue(containsWhitespace(" a"));
assertTrue(containsWhitespace("abc "));
assertTrue(containsWhitespace("a b"));
assertTrue(containsWhitespace("a b"));
}
}
Output
Reference
https://junit.org/junit5/docs/current/api/org/junit/jupiter/api/Assertions.html
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