Use the Hamcrest framework for abnormal assertions and abnormal processing
Use the Hamcrest framework for abnormal assertions and abnormal processing
When writing a Java application, abnormal processing is an essential part.The use of the HAMCREST framework can more conveniently perform abnormal assertions and abnormal processing, making the code more clear and readable.This article will introduce how to use the HAMCREST framework for abnormal assertions and abnormal processing, and provide Java code examples.
First, why use the HAMCREST framework for abnormal assertions and abnormalities?
In the traditional Junit assertion, Try-Catch blocks are usually used to capture abnormalities and assert.However, this method may cause redundancy of code and make it difficult to maintain and understand abnormal treatment.The HAMCREST framework provides a more concise and more readable assertion syntax, and it can also be better integrated into the Junit test framework.Therefore, using the HAMCREST framework for abnormal assertions and abnormal processing can make the code more concise and maintainable.
Second, use the Hamcrest framework for abnormal assertions
1. Add Hamcrest dependencies
First, the dependencies of Hamcrest need to be added to the project.Hamcrest can be introduced into a project through building tools such as Maven and Gradle.
2. Odomy
When using the HAMCREST framework for abnormal assertions, you can assert through the corresponding method in the Matches class.For example, to assert that a method will throw the nullpoINTEEREPTION exception, you can use the `Throwsexception" method in `ORG.HAMCREST.MATCHERS` to assert.
The following is an example code:
import org.hamcrest.Matchers;
import org.junit.Test;
public class ExceptionTest {
@Test
public void testException() {
// Ecclail triggering nullpoIntterexception
String str = null;
org.hamcrest.MatcherAssert.assertThat(() -> str.length(), Matchers.throwsException(NullPointerException.class));
}
}
In the above sample code, we used the `Matcherassert.assertthat` method for abnormal assertions.`ThrowSexception` method to receive an anonymous function as a parameter, which contains code logic that may cause abnormalities.In this example, we asserted that `str.Length ()` will cause nullpointerexception abnormalities.
Third, use the Hamcrest framework for abnormal treatment
1. Abnormal treatment
When using HAMCREST for abnormal processing, you can use the `IS (Instanceof) method in the MATCHERS class to verify the captured abnormal type.Then, perform corresponding abnormal treatment logic according to abnormal types.
The following is an example code:
import org.hamcrest.Matchers;
import org.junit.Test;
public class ExceptionHandlingTest {
@Test
public void testExceptionHandling() {
try {
// Throw ArithmeticException anomalies
int result = 1 / 0;
} catch (Exception e) {
// Abnormal treatment
org.hamcrest.MatcherAssert.assertThat(e, Matchers.is(instanceOf(ArithmeticException.class)));
System.out.println ("" Occasion: " + E.getMessage ());
}
}
}
In the above example code, we used the `Matcherassert.assertthat` method to make an abnormal type of assertion.Through the `IS (Instanceof) method, you can determine whether the captured abnormality is the type we expect.If the abnormal type meets the expectations, then we can perform the corresponding abnormal processing logic.
Fourth, summary
The HAMCREST framework provides more concise and more readable abnormal assertions and abnormal processing grammar, making the code more clear and readable.This article introduces how to use the Hamcrest framework for abnormal assertions and abnormal processing, and provide the corresponding Java code example.By using the HAMCREST framework, it can be more convenient to perform abnormal assertions and abnormal processing, making the code more elegant and maintained.
