ArchUnit：检查软件包是否相互依赖的最优雅的方法

Question

I have two packages com.myapp.foo and com.myapp.bar and I want to know the most elegant way to explicitly check if those two packages (and only those, as there are some more com.myapp.XX ) do not depend on each other.

This is what I have right now (working splendid):

    SliceAssignment packagesFooAndBar = new SliceAssignment() {
        @Override
        public String getDescription() {
            return "foo and bar";
        }

        @Override
        public SliceIdentifier getIdentifierOf(JavaClass javaClass) {
            if (javaClass.getPackageName().startsWith("com.myapp.foo")) {
                return SliceIdentifier.of("foo");
            }
            if (javaClass.getPackageName().startsWith("com.myapp.bar")) {
                return SliceIdentifier.of("bar");
            }
            return SliceIdentifier.ignore();
        }
    };
    @ArchTest
    final ArchRule packagesFooAndBarNotDependOnEachOther = SlicesRuleDefinition
        .slices()
        .assignedFrom(packagesFooAndBar)
        .should()
        .notDependOnEachOther();

Is there a more elegant way, maybe without using the SliceAssignment ? Thanks!

Answer 1

I would probably use two rules.

@ArchTest
final ArchRule fooShouldNotDependOnBar = ArchRuleDefinition
.classes()
.that().resideInAnyPackage("com.myapp.foo")
.should().onlyDependOnClassesThat()
.resideOutsideOfPackage("com.myapp.bar");

@ArchTest
final ArchRule barShouldNotDependOnFoo = ArchRuleDefinition
.classes()
.that().resideInAnyPackage("com.myapp.bar")
.should().onlyDependOnClassesThat()
.resideOutsideOfPackage("com.myapp.foo");

If you want to write the same in a single rule without custom classes, the following should work. I'm not sure if I would call it elegant though, since it's seems a bit complex. There are probably better ways to write it in a single rule.

@ArchTest
final ArchRule packagesFooAndBarNotDependOnEachOther = SlicesRuleDefinition
    .slices()
    .matching("com.myapp.(*)")
    .should()
    .notDependOnEachOther()
    .ignoreDependency(
        JavaClass.Predicates.resideOutsideOfPackages("com.myapp.foo", "com.myapp.bar"),
        DescribedPredicate.alwaysTrue())
    .ignoreDependency(
        DescribedPredicate.alwaysTrue(),
        JavaClass.Predicates.resideOutsideOfPackages("com.myapp.foo", "com.myapp.bar"))
    );

The rule first matches all direct sub-packages of com.myapp . The first ignoreDependency then excludes all dependencies from classes outside of the given packages (to allow eg com.myapp.xx to access com.myapp.foo ). The second ignoreDependency excludes all dependencies from the given packages to any outside package (to allow eg com.myapp.foo to access com.myapp.xx ).