allow for empty layers in OnionArchitecture (#271)

Signed-off-by: Manfred Hanke <Manfred.Hanke@tngtech.com>
TNG · Jan 9, 2020 · 9db4047 · 9db4047
1 parent e698a71
commit 9db4047
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Showing 2 changed files with 36 additions and 3 deletions.
diff --git a/archunit/src/main/java/com/tngtech/archunit/library/Architectures.java b/archunit/src/main/java/com/tngtech/archunit/library/Architectures.java
@@ -391,12 +391,12 @@ public static final class OnionArchitecture implements ArchRule {
         private static final String APPLICATION_SERVICE_LAYER = "application service";
         private static final String ADAPTER_LAYER = "adapter";
 
+        private final Optional<String> overriddenDescription;
         private String[] domainModelPackageIdentifiers = new String[0];
         private String[] domainServicePackageIdentifiers = new String[0];
         private String[] applicationPackageIdentifiers = new String[0];
         private Map<String, String[]> adapterPackageIdentifiers = new LinkedHashMap<>();
-
-        private final Optional<String> overriddenDescription;
+        private boolean allowEmptyLayers = false;
 
         private OnionArchitecture() {
             overriddenDescription = Optional.absent();
@@ -438,6 +438,12 @@ public OnionArchitecture adapter(String name, String... packageIdentifiers) {
             return this;
         }
 
+        @PublicAPI(usage = ACCESS)
+        public OnionArchitecture allowEmptyLayers(boolean allowEmptyLayers) {
+            this.allowEmptyLayers = allowEmptyLayers;
+            return this;
+        }
+
         private LayeredArchitecture layeredArchitectureDelegate() {
             LayeredArchitecture layeredArchitectureDelegate = layeredArchitecture()
                     .layer(DOMAIN_MODEL_LAYER).definedBy(domainModelPackageIdentifiers)
@@ -446,7 +452,8 @@ private LayeredArchitecture layeredArchitectureDelegate() {
                     .layer(ADAPTER_LAYER).definedBy(concatenateAll(adapterPackageIdentifiers.values()))
                     .whereLayer(DOMAIN_MODEL_LAYER).mayOnlyBeAccessedByLayers(DOMAIN_SERVICE_LAYER, APPLICATION_SERVICE_LAYER, ADAPTER_LAYER)
                     .whereLayer(DOMAIN_SERVICE_LAYER).mayOnlyBeAccessedByLayers(APPLICATION_SERVICE_LAYER, ADAPTER_LAYER)
-                    .whereLayer(APPLICATION_SERVICE_LAYER).mayOnlyBeAccessedByLayers(ADAPTER_LAYER);
+                    .whereLayer(APPLICATION_SERVICE_LAYER).mayOnlyBeAccessedByLayers(ADAPTER_LAYER)
+                    .allowEmptyLayers(allowEmptyLayers);
 
             for (Map.Entry<String, String[]> adapter : adapterPackageIdentifiers.entrySet()) {
                 String adapterLayer = getAdapterLayer(adapter.getKey());

diff --git a/archunit/src/test/java/com/tngtech/archunit/library/ArchitecturesTest.java b/archunit/src/test/java/com/tngtech/archunit/library/ArchitecturesTest.java
@@ -312,6 +312,32 @@ public void onion_architecture_gathers_all_violations() {
         assertPatternMatches(result.getFailureReport().getDetails(), expectedViolations.toPatterns());
     }
 
+    @Test
+    @DataProvider(value = {"true", "false", "null"})
+    public void onion_architecture_allows_or_rejects_empty_layers(Boolean allowEmptyLayers) {
+        OnionArchitecture architecture = onionArchitecture()
+                .domainModels(absolute("onionarchitecture.domain.model.does.not.exist"))
+                .domainServices(absolute("onionarchitecture.domain.service.not.there"))
+                .applicationServices(absolute("onionarchitecture.application.http410"));
+        if (allowEmptyLayers != null) {
+            architecture.allowEmptyLayers(allowEmptyLayers);
+        }
+
+        JavaClasses classes = new ClassFileImporter().importPackages(absolute("onionarchitecture"));
+
+        EvaluationResult result = architecture.evaluate(classes);
+        boolean expectViolation = allowEmptyLayers != Boolean.TRUE;
+        assertThat(result.hasViolation()).as("result of evaluating empty layers has violation").isEqualTo(expectViolation);
+        if (expectViolation) {
+            assertPatternMatches(result.getFailureReport().getDetails(), ImmutableSet.of(
+                    expectedEmptyLayer("adapter"), expectedEmptyLayer("application service"),
+                    expectedEmptyLayer("domain model"), expectedEmptyLayer("domain service")
+            ));
+        } else {
+            assertThat(result.getFailureReport().isEmpty()).as("failure report").isTrue();
+        }
+    }
+
     private String singleLine(EvaluationResult result) {
         return Joiner.on(NEW_LINE_REPLACE).join(result.getFailureReport().getDetails()).replace("\n", NEW_LINE_REPLACE);
     }