add automatic conversions to violation handling

The extensive freedom of how to create a `ConditionEvent` causes problems for any client that needs more structured results (e.g. tools).
`ViolationHandler` provides a convenient API to obtain only those sort of violations that can be handled by a client (e.g. tackling dependencies).
However, the type of the `correspondingObject` attached to the `ConditionEvent` can take many forms.
From classes to methods, method calls, dependencies or aggregated dependencies (like module dependencies) it's hard to determine the possibilities and handle them all.
Furthermore, the type of some objects (e.g. `ComponentDependency` isn't even public,
so there is hardly any clean way to handle these objects.

To mitigate this a little we now support transparent conversions between compatible objects.
E.g. a component dependency can also be considered a set of class dependencies.
`ViolationHandler` now allows to be used including these conversions that are implemented by standard ArchUnit objects where reasonable.
This allows e.g. to obtain all module dependencies as `Set<Dependency>` for every violation.

Signed-off-by: Peter Gafert <peter.gafert@archunit.org>

archunit-integration-test/src/test/java/com/tngtech/archunit/PublicAPIRules.java

@@ -42,6 +42,7 @@
 import static com.tngtech.archunit.core.domain.JavaMember.Predicates.declaredIn;
 import static com.tngtech.archunit.core.domain.JavaModifier.FINAL;
 import static com.tngtech.archunit.core.domain.JavaModifier.PUBLIC;
+import static com.tngtech.archunit.core.domain.JavaModifier.SYNTHETIC;
 import static com.tngtech.archunit.core.domain.properties.CanBeAnnotated.Predicates.annotatedWith;
 import static com.tngtech.archunit.core.domain.properties.HasModifiers.Predicates.modifier;
 import static com.tngtech.archunit.core.domain.properties.HasName.Utils.namesOf;
@@ -95,6 +96,7 @@ public class PublicAPIRules {
     public static final ArchRule all_public_API_members_are_accessible =
             members()
                     .that().areAnnotatedWith(PublicAPI.class)
+                    .and().doNotHaveModifier(SYNTHETIC)
                     .should(bePubliclyAccessible());
 
     @ArchTest

archunit-integration-test/src/test/java/com/tngtech/archunit/integration/ExpectedOnionArchitectureByAnnotationFailures.java

@@ -53,24 +53,24 @@ static void addTo(ExpectedTestFailures expectedTestFailures) {
                         .inLine(18))
                 .by(callFromMethod(AdministrationCLI.class, "handle", String[].class, AdministrationPort.class)
                         .toMethod(ProductRepository.class, "getTotalCount")
-                        .inLine(19).asDependency())
+                        .inLine(19))
                 .by(callFromMethod(ShoppingController.class, "addToShoppingCart", UUID.class, UUID.class, int.class)
                         .toConstructor(ProductId.class, UUID.class)
-                        .inLine(20).asDependency())
+                        .inLine(20))
                 .by(callFromMethod(ShoppingController.class, "addToShoppingCart", UUID.class, UUID.class, int.class)
                         .toConstructor(ShoppingCartId.class, UUID.class)
-                        .inLine(20).asDependency())
+                        .inLine(20))
                 .by(method(ShoppingService.class, "addToShoppingCart").withParameter(ProductId.class))
                 .by(method(ShoppingService.class, "addToShoppingCart").withParameter(ShoppingCartId.class))
                 .by(callFromMethod(ShoppingService.class, "addToShoppingCart", ShoppingCartId.class, ProductId.class, OrderQuantity.class)
                         .toMethod(ShoppingCartRepository.class, "read", ShoppingCartId.class)
-                        .inLine(21).asDependency())
+                        .inLine(21))
                 .by(callFromMethod(ShoppingService.class, "addToShoppingCart", ShoppingCartId.class, ProductId.class, OrderQuantity.class)
                         .toMethod(ProductRepository.class, "read", ProductId.class)
-                        .inLine(22).asDependency())
+                        .inLine(22))
                 .by(callFromMethod(ShoppingService.class, "addToShoppingCart", ShoppingCartId.class, ProductId.class, OrderQuantity.class)
                         .toMethod(ShoppingCartRepository.class, "save", ShoppingCart.class)
-                        .inLine(25).asDependency())
+                        .inLine(25))
                 .by(constructor(OrderItem.class).withParameter(OrderQuantity.class))
                 .by(field(OrderItem.class, "quantity").ofType(OrderQuantity.class));
     }

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/CyclicErrorMatcher.java

@@ -90,6 +90,11 @@ private String detailLinePattern(String string) {
         return ".*" + quote(string) + ".*";
     }
 
+    @Override
+    public void addTo(HandlingAssertion handlingAssertion) {
+        details.values().forEach(relation -> relation.addTo(handlingAssertion));
+    }
+
     @Override
     public String getDescription() {
         return String.format("Message contains cycle description '%s' and details '%s'",

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/ExpectedAccess.java

@@ -166,6 +166,9 @@ public ExpectedDependency asDependency() {
         @Override
         public void addTo(HandlingAssertion assertion) {
             assertion.byFieldAccess(this);
+            if (!getOrigin().getDeclaringClass().equals(getTarget().getDeclaringClass())) {
+                assertion.byDependency(asDependency());
+            }
         }
     }
 
@@ -192,6 +195,9 @@ public void addTo(HandlingAssertion assertion) {
             } else {
                 assertion.byMethodCall(this);
             }
+            if (!getOrigin().getDeclaringClass().equals(getTarget().getDeclaringClass())) {
+                assertion.byDependency(asDependency());
+            }
         }
     }
 }

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/ExpectedModuleDependency.java

@@ -5,9 +5,8 @@
 import java.util.Set;
 
 import com.google.common.base.Joiner;
-import com.tngtech.archunit.core.domain.Dependency;
+import com.tngtech.archunit.testutils.ExpectedRelation.LineAssociation;
 
-import static com.tngtech.archunit.testutils.MessageAssertionChain.matchesLine;
 import static java.util.regex.Pattern.quote;
 
 public class ExpectedModuleDependency implements MessageAssertionChain.Link {
@@ -22,8 +21,13 @@ public static ModuleDependencyCreator fromModule(String moduleName) {
         return new ModuleDependencyCreator(moduleName);
     }
 
-    public static UncontainedCreator uncontainedFrom(Class<?> origin) {
-        return new UncontainedCreator(origin);
+    public static MessageAssertionChain.Link uncontained(ExpectedRelation call) {
+        return new ExpectedUncontainedModuleDependency(call);
+    }
+
+    @Override
+    public void addTo(HandlingAssertion handlingAssertion) {
+        details.forEach(it -> it.addTo(handlingAssertion));
     }
 
     @Override
@@ -58,51 +62,38 @@ public ExpectedModuleDependency toModule(String moduleName) {
         }
     }
 
-    public static class UncontainedCreator {
-        private final Class<?> origin;
-
-        private UncontainedCreator(Class<?> origin) {
-            this.origin = origin;
-        }
+    private static class ExpectedUncontainedModuleDependency implements MessageAssertionChain.Link {
+        private final ExpectedRelation delegate;
 
-        public ExpectedUncontainedModuleDependency to(Class<?> target) {
-            return new ExpectedUncontainedModuleDependency(origin, target);
-        }
-    }
-
-    private static class ExpectedUncontainedModuleDependency implements MessageAssertionChain.Link, ExpectedRelation {
-        private final String dependencyPattern;
-        private final MessageAssertionChain.Link delegate;
-
-        private ExpectedUncontainedModuleDependency(Class<?> origin, Class<?> target) {
-            dependencyPattern = String.format("Dependency not contained in any module: .*%s.*%s.*",
-                    quote(origin.getName()), quote(target.getName()));
-            this.delegate = matchesLine(dependencyPattern);
+        private ExpectedUncontainedModuleDependency(ExpectedRelation delegate) {
+            this.delegate = delegate;
         }
 
         @Override
         public void addTo(HandlingAssertion assertion) {
-            assertion.byDependency(this);
-        }
-
-        @Override
-        public void associateLines(LineAssociation association) {
-            association.associateIfPatternMatches(dependencyPattern);
-        }
-
-        @Override
-        public boolean correspondsTo(Object object) {
-            return object instanceof Dependency;
+            delegate.addTo(assertion);
         }
 
         @Override
         public Result filterMatching(List<String> lines) {
-            return delegate.filterMatching(lines);
+            Result.Builder builder = new Result.Builder();
+            delegate.associateLines(new LineAssociation() {
+                @Override
+                public void associateIfPatternMatches(String pattern) {
+                    builder.matchesLine("Dependency not contained in any module:" + pattern);
+                }
+
+                @Override
+                public void associateIfStringIsContained(String string) {
+                    associateIfPatternMatches(".*" + quote(string) + ".*");
+                }
+            });
+            return builder.build(lines);
         }
 
         @Override
         public String getDescription() {
-            return delegate.getDescription();
+            return "Uncontained module dependency: " + delegate;
         }
     }
 }

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/ExpectedRelation.java

@@ -3,7 +3,7 @@
 import com.tngtech.archunit.core.domain.JavaAccess;
 import com.tngtech.archunit.lang.ConditionEvent;
 
-interface ExpectedRelation {
+public interface ExpectedRelation {
 
     void addTo(HandlingAssertion assertion);
 

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/ExpectedTestFailures.java

@@ -372,9 +372,7 @@ void by(ExpectedDependency inheritance) {
 
         void by(MessageAssertionChain.Link assertion) {
             expectedViolation.by(assertion);
-            if (assertion instanceof ExpectedRelation) {
-                ((ExpectedRelation) assertion).addTo(handlingAssertion);
-            }
+            assertion.addTo(handlingAssertion);
         }
 
         ExpectedViolationToAssign copy() {

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/HandlingAssertion.java

@@ -5,6 +5,7 @@
 import java.util.Iterator;
 import java.util.Set;
 import java.util.TreeSet;
+import java.util.function.BiPredicate;
 
 import com.google.common.base.Joiner;
 import com.google.common.collect.Sets;
@@ -16,14 +17,13 @@
 import com.tngtech.archunit.core.domain.JavaMethodCall;
 import com.tngtech.archunit.lang.EvaluationResult;
 
-import static com.google.common.collect.Iterables.getOnlyElement;
 import static com.google.common.collect.Sets.union;
 import static java.lang.System.lineSeparator;
 import static java.util.Collections.emptySet;
 import static java.util.Collections.singleton;
 import static java.util.stream.Collectors.toSet;
 
-class HandlingAssertion {
+public class HandlingAssertion {
     private final Set<ExpectedRelation> expectedFieldAccesses;
     private final Set<ExpectedRelation> expectedMethodCalls;
     private final Set<ExpectedRelation> expectedConstructorCalls;
@@ -57,8 +57,8 @@ void byMethodCall(ExpectedRelation call) {
         expectedMethodCalls.add(call);
     }
 
-    void byDependency(ExpectedRelation inheritance) {
-        expectedDependencies.add(inheritance);
+    void byDependency(ExpectedRelation dependency) {
+        expectedDependencies.add(dependency);
     }
 
     static HandlingAssertion ofRule() {
@@ -131,15 +131,13 @@ private Set<String> evaluateDependencies(EvaluationResult result) {
     }
 
     private Set<String> removeExpectedAccesses(Collection<?> violatingObjects, Set<? extends ExpectedRelation> left) {
-        Object violatingObject = getOnlyElement(violatingObjects);
-        for (Iterator<? extends ExpectedRelation> actualMethodCalls = left.iterator(); actualMethodCalls.hasNext(); ) {
-            ExpectedRelation next = actualMethodCalls.next();
-            if (next.correspondsTo(violatingObject)) {
-                actualMethodCalls.remove();
-                return emptySet();
-            }
+        removeMatchingElements(violatingObjects, left, (object, relation) -> relation.correspondsTo(object));
+
+        if (!violatingObjects.isEmpty()) {
+            return singleton("Unhandled violations: " + violatingObjects);
         }
-        return singleton("Unexpected violation handling: " + violatingObject);
+
+        return emptySet();
     }
 
     private Set<String> errorMessagesFrom(Set<?> set) {
@@ -150,6 +148,19 @@ HandlingAssertion copy() {
         return new HandlingAssertion(expectedFieldAccesses, expectedMethodCalls, expectedConstructorCalls, expectedDependencies);
     }
 
+    private <T, U> void removeMatchingElements(Collection<T> actual, Collection<U> expected, BiPredicate<T, U> matches) {
+        for (Iterator<? extends T> actualIterator = actual.iterator(); actualIterator.hasNext(); ) {
+            T actualElement = actualIterator.next();
+            for (Iterator<? extends U> expectedIterator = expected.iterator(); expectedIterator.hasNext(); ) {
+                if (matches.test(actualElement, expectedIterator.next())) {
+                    actualIterator.remove();
+                    expectedIterator.remove();
+                    break;
+                }
+            }
+        }
+    }
+
     static class Result {
         private final Set<String> errorMessages = new TreeSet<>();
 

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/MessageAssertionChain.java

@@ -189,6 +189,9 @@ public interface Link {
 
         String getDescription();
 
+        default void addTo(HandlingAssertion handlingAssertion) {
+        }
+
         @Internal
         class Result {
             private final boolean matches;

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/SliceDependencyErrorMatcher.java

@@ -49,6 +49,11 @@ public Result filterMatching(List<String> lines) {
         return new Result(true, remainingLines);
     }
 
+    @Override
+    public void addTo(HandlingAssertion handlingAssertion) {
+        expectedAccesses.forEach(it -> it.addTo(handlingAssertion));
+    }
+
     @Override
     public String getDescription() {
         return Joiner.on(System.lineSeparator()).join(ImmutableList.builder()

archunit/src/main/java/com/tngtech/archunit/core/Convertible.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2014-2024 TNG Technology Consulting GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.tngtech.archunit.core;
+
+import java.util.Set;
+
+import com.tngtech.archunit.PublicAPI;
+import com.tngtech.archunit.core.domain.Dependency;
+import com.tngtech.archunit.core.domain.JavaAccess;
+
+import static com.tngtech.archunit.PublicAPI.Usage.INHERITANCE;
+
+/**
+ * Can be implemented to express that this object might also be considered as object(s) of a different type.
+ * E.g. {@link JavaAccess} and {@link Dependency} (compare {@link #convertTo(Class)}).
+ */
+@PublicAPI(usage = INHERITANCE)
+public interface Convertible {
+    /**
+     * Converts this type to a set of other types.
+     * For example a {@link JavaAccess} can also be
+     * considered a {@link Dependency}, so <code>javaAccess.convertTo(Dependency.class)</code>
+     * will yield a set with a single {@link Dependency} representing this access.
+     * Or a component dependency grouping many class dependencies could be considered a set of exactly
+     * these class dependencies.
+     * The result will be an empty set if no conversion is possible
+     * (e.g. calling <code>javaAccess.convertTo(Integer.class)</code>.
+     *
+     * @param type The type to convert to
+     * @return A set of converted elements, empty if no conversion is possible
+     */
+    <T> Set<T> convertTo(Class<T> type);
+}