Common utilities for working with JUnit:
- assertion of exceptions, as well as exception details, such as message and cause
- assertion of strings contents
- testing that a class cannot be instantiated
Note: Consider the following static import declarations for readability:
import static net.obvj.junit.utils.matchers.AdvancedMatchers.*;
import static org.hamcrest.CoreMatchers.*;
import static org.hamcrest.MatcherAssert.assertThat;The following assertion is true if the examined method throws a NullPointerException:
assertThat(() -> myObject.doStuff(null),
throwsException(NullPointerException.class));To test the exception message, add withMessageContaining ...
assertThat(() -> myObject.doStuff(null),
throwsException(NullPointerException.class)
.withMessageContaining("ERR-120008"));... or combine a String matcher:
assertThat(() -> agent.loadSchemaFile("bad-schema.xsd"),
throwsException(AgentConfigurationException.class)
.withMessage(
either(startsWith("ERR-0001"))
.or(containsAny("invalid schema").ignoreCase())));If required, you can also test the exception cause:
assertThat(() -> myObject.doStuff(null),
throwsException(MyException.class).withMessageContaining("ERR-120008")
.withCause(NullPointerException.class));And more:
assertThat(() -> myObject.doStuff(null),
throwsException(MyException.class).withMessageContaining("ERR-120008")
.withCause(
exception(NullPointerException.class)
.withMessage("stuff cannot be null")));The following assertion is particularly useful for utility classes:
assertThat(TestUtils.class, instantiationNotAllowed());A matching class shall have all constructors declared as private and throw an exception inside the default constructor.
The following examples represent some successful assertions using the Advanced String matcher:
assertThat("The quick brown fox jumps over the lazy dog", containsAll("fox", "dog"));
assertThat("The quick brown fox jumps over the lazy dog", containsAny("FOX", "dragon").ignoreCase());
assertThat("The quick brown fox jumps over the lazy dog", containsNone("centaur"));Sometimes, it's more meaningful to check whether a number is positive or negative than testing the value itself, especially in situations where the exact value is unpredictable:
assertThat(stopwatch.elapsedTime(), isPositive());
assertThat(duration.compareTo(otherDuration), isNegative());If you are using Maven, add junit-utils as a dependency in your pom.xml file:
<dependency>
<groupId>net.obvj</groupId>
<artifactId>junit-utils</artifactId>
<version>1.7.0</version>
</dependency>If you use other dependency management systems (such as Gradle, Grape, Ivy, etc.) click here.