vinothlabs / units4j

A home for additional useful unit testing modules for Java.

units4j

A home for additional useful unit testing modules for Java.

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Features

• Asserting test coverage
• Asserting package dependencies
• Asserting methods are not used
• Assert that JPA entities are valid
• Assert that methods have information if null is allowed or not
• Assert that fields with @JsonbProperty annotation are not final

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Asserting test coverage

A good approach is to have at least one test class for every production class.

If you have classes this rule-of-thumb does not apply, you can:

• Write a dummy test class with a comment that describes why not...
• Use an AssertCoverage.ClassFilter to exclude the classes

@Test
public void testCoverage() {
    AssertCoverage.assertEveryClassHasATest(new File("src/main/java"));
}

Asserting package dependencies

It's a good practice enforcing package dependencies to avoid high coupling and package cycles.

You simply define a dependency description in your "src/test/resources" folder. For an example see units4j.xml).

@Test
public void testAssertDependencies() {
    AssertDependencies.assertRules(getClass(), "/units4j.xml", new File("target/classes"));
}

Asserting methods are not used

Example: Prevent a java.lang.ArithmeticException Non-terminating decimal expansion; no exact representable decimal result." caused by calling BigDecimal's divide or setScale without a rounding mode:

// Path to '*.class' files
File classesDir = new File("target/classes");

// Can be used to exclude some files/packages
FileFilter fileFilter = new FileFilter() {
    @Override
    public boolean accept(File file) {
        return !file.getPath().contains("my/pkg/to/exclude");
    }
};

// Define methods to find
MCAMethod divide = new MCAMethod("java.math.BigDecimal", "java.math.BigDecimal divide(java.math.BigDecimal)");
MCAMethod setScale = new MCAMethod("java.math.BigDecimal","java.math.BigDecimal setScale(int)");

// Fails if any class calls one of the two methods
AssertUsage.assertMethodsNotUsed(classesDir, fileFilter, divide, setScale);

Assert that JPA entities are valid

Uses JBoss Jandex to validate JPA entity classes.

import static org.fuin.units4j.JandexAssert.assertThat;

// Collect all class files
File dir = new File("target/classes");
List<File> classFiles = Units4JUtils.findAllClasses(dir);
Index index = Units4JUtils.indexAllClasses(classFiles);

// Verify that all classes annotated with @Entity or @MappedSuperclass observe 
// the rules for JPA entities (Class not final + No final methods + ...).
assertThat(index).hasOnlyValidJpaEntities();

Assert that methods have information if null is allowed or not

WORK IN PROGRESS See Issue #9

It's a good style to define a precondition for method arguments and postconditions for return values of externally used methods. Especially the questions "Can I pass null?" or "Does the method return null values?" is a common source of confusion. This assertion makes sure that all return values and parameters of all public, protected and package-private methods have either a @NotNull or a @Nullable annotation.

Example:

public interface MyInterface {
    
    // Post condition says the return value is never null
    @NotNull
    public Boolean myMethodA();
    
    // Pre condition says the first value cannot be null, but it's OK for the second argument
    public void myMethodB(@NotNull Integer abc, @Nullable String def);

    // Post condition says the return value may be null
    @Nullable
    public Long myMethodC();
    
}   

Test:

import static org.fuin.units4j.JandexAssert.assertThat;

// Collect all class files
File dir = new File("target/classes");
List<File> classFiles = Units4JUtils.findAllClasses(dir);
Index index = Units4JUtils.indexAllClasses(classFiles);

// Verify that all methods make a statement if null is allowed or not 
assertThat(index).hasNullabilityInfoOnAllMethods();

Assert that fields with @JsonbProperty annotation are not final

Verifies that no field that has a @JsonbProperty annotation. The deserialization using a Eclipse Yasson FieldAccessStrategy will fail otherwise silently.

Uses JBoss Jandex to validate JSON-B fields.

import static org.fuin.units4j.JandexAssert.assertThat;

// Collect all class files
File dir = new File("target/classes");
List<File> classFiles = Units4JUtils.findAllClasses(dir);
Index index = Units4JUtils.indexAllClasses(classFiles);

// Verify that no field that has a 'javax.json.bind.annotation.JsonbProperty' annotation. 
// The deserialization using a 'org.eclipse.yasson.FieldAccessStrategy' will fail otherwise.
assertThat(index).hasNoFinalFieldsWithJsonbPropertyAnnotation();

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Snapshots

Snapshots can be found on the OSS Sonatype Snapshots Repository.

Add the following to your .m2/settings.xml to enable snapshots in your Maven build:

<repository>
    <id>sonatype.oss.snapshots</id>
    <name>Sonatype OSS Snapshot Repository</name>
    <url>http://oss.sonatype.org/content/repositories/snapshots</url>
    <releases>
        <enabled>false</enabled>
    </releases>
    <snapshots>
        <enabled>true</enabled>
    </snapshots>
</repository>