WFCORE-6347 Add convenience method to map a dependency to an alternate type.

service/src/main/java/org/wildfly/service/Dependency.java

@@ -18,6 +18,20 @@
  */
 public interface Dependency<B extends ServiceBuilder<?>, V> extends Consumer<B>, Supplier<V> {
 
+    default <R> Dependency<B, R> map(Function<V, R> mapper) {
+        return new Dependency<>() {
+            @Override
+            public void accept(B builder) {
+                Dependency.this.accept(builder);
+            }
+
+            @Override
+            public R get() {
+                return mapper.apply(Dependency.this.get());
+            }
+        };
+    }
+
     class SimpleDependency<B extends ServiceBuilder<?>, V> implements Dependency<B, V> {
 
         private final V value;

service/src/main/java/org/wildfly/service/ServiceDependency.java

@@ -4,6 +4,8 @@
  */
 package org.wildfly.service;
 
+import java.util.function.Function;
+
 import org.jboss.msc.service.ServiceBuilder;
 import org.jboss.msc.service.ServiceName;
 
@@ -13,6 +15,21 @@
  */
 public interface ServiceDependency<V> extends Dependency<ServiceBuilder<?>, V> {
 
+    @Override
+    default <R> ServiceDependency<R> map(Function<V, R> mapper) {
+        return new ServiceDependency<>() {
+            @Override
+            public void accept(ServiceBuilder<?> builder) {
+                ServiceDependency.this.accept(builder);
+            }
+
+            @Override
+            public R get() {
+                return mapper.apply(ServiceDependency.this.get());
+            }
+        };
+    }
+
     /**
      * Returns a pseudo-dependency supplying a fixed value.
      * @return a dependency supplier

service/src/test/java/org/wildfly/service/ServiceDependencyTestCase.java

@@ -6,7 +6,9 @@
 
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verifyNoInteractions;
 
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.jboss.msc.service.ServiceBuilder;
@@ -24,27 +26,66 @@ public class ServiceDependencyTestCase {
     @Test
     public void simple() {
         ServiceBuilder<?> builder = mock(ServiceBuilder.class);
-        Object value = new Object();
+        String value = "foo";
 
         ServiceDependency<Object> dependency = ServiceDependency.of(value);
 
         dependency.accept(builder);
 
+        verifyNoInteractions(builder);
+
         Assert.assertSame(value, dependency.get());
+
+        ServiceDependency<Object> mapped = dependency.map(Functions.cast(Function.identity()));
+
+        mapped.accept(builder);
+
+        verifyNoInteractions(builder);
+
+        Assert.assertSame(value, mapped.get());
+
+        ServiceDependency<String> cast = mapped.map(String.class::cast);
+
+        cast.accept(builder);
+
+        verifyNoInteractions(builder);
+
+        Assert.assertSame(value, cast.get());
     }
 
     @Test
     public void service() {
         ServiceBuilder<?> builder = mock(ServiceBuilder.class);
         ServiceName name = ServiceName.JBOSS;
-        Supplier<Object> injection = Functions.constantSupplier(new Object());
+        Supplier<String> injection1 = Functions.constantSupplier("foo");
+        Supplier<String> injection2 = Functions.constantSupplier("bar");
+        Supplier<String> injection3 = Functions.constantSupplier("qux");
 
         ServiceDependency<Object> dependency = ServiceDependency.on(name);
 
-        doReturn(injection).when(builder).requires(name);
+        doReturn(injection1, injection2, injection3).when(builder).requires(name);
 
         dependency.accept(builder);
 
-        Assert.assertSame(injection.get(), dependency.get());
+        Assert.assertSame(injection1.get(), dependency.get());
+
+        ServiceDependency<Object> mapped = dependency.map(Functions.cast(Function.identity()));
+
+        Assert.assertSame(injection1.get(), mapped.get());
+
+        mapped.accept(builder);
+
+        Assert.assertSame(injection2.get(), mapped.get());
+        Assert.assertSame(injection2.get(), dependency.get());
+
+        ServiceDependency<String> cast = mapped.map(String.class::cast);
+
+        Assert.assertSame(injection2.get(), cast.get());
+
+        cast.accept(builder);
+
+        Assert.assertSame(injection3.get(), cast.get());
+        Assert.assertSame(injection3.get(), mapped.get());
+        Assert.assertSame(injection3.get(), dependency.get());
     }
 }

subsystem/src/main/java/org/wildfly/subsystem/service/ServiceDependency.java

@@ -6,6 +6,7 @@
 
 import java.util.Arrays;
 import java.util.Map;
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.jboss.as.controller.RequirementServiceBuilder;
@@ -23,6 +24,21 @@
  */
 public interface ServiceDependency<V> extends Dependency<RequirementServiceBuilder<?>, V> {
 
+    @Override
+    default <R> ServiceDependency<R> map(Function<V, R> mapper) {
+        return new ServiceDependency<>() {
+            @Override
+            public void accept(RequirementServiceBuilder<?> builder) {
+                ServiceDependency.this.accept(builder);
+            }
+
+            @Override
+            public R get() {
+                return mapper.apply(ServiceDependency.this.get());
+            }
+        };
+    }
+
     /**
      * Returns a dependency on the service with the specified name.
      * @param <T> the dependency type

subsystem/src/test/java/org/wildfly/subsystem/service/ServiceDependencyTestCase.java

@@ -6,7 +6,9 @@
 
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verifyNoInteractions;
 
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.jboss.as.controller.RequirementServiceBuilder;
@@ -24,27 +26,66 @@ public class ServiceDependencyTestCase {
     @Test
     public void simple() {
         RequirementServiceBuilder<?> builder = mock(RequirementServiceBuilder.class);
-        Object value = new Object();
+        String value = "foo";
 
         ServiceDependency<Object> dependency = ServiceDependency.of(value);
 
         dependency.accept(builder);
 
+        verifyNoInteractions(builder);
+
         Assert.assertSame(value, dependency.get());
+
+        ServiceDependency<Object> mapped = dependency.map(Functions.cast(Function.identity()));
+
+        mapped.accept(builder);
+
+        verifyNoInteractions(builder);
+
+        Assert.assertSame(value, mapped.get());
+
+        ServiceDependency<String> cast = mapped.map(String.class::cast);
+
+        cast.accept(builder);
+
+        verifyNoInteractions(builder);
+
+        Assert.assertSame(value, cast.get());
     }
 
     @Test
     public void service() {
         RequirementServiceBuilder<?> builder = mock(RequirementServiceBuilder.class);
         ServiceName name = ServiceName.JBOSS;
-        Supplier<Object> injection = Functions.constantSupplier(new Object());
+        Supplier<String> injection1 = Functions.constantSupplier("foo");
+        Supplier<String> injection2 = Functions.constantSupplier("bar");
+        Supplier<String> injection3 = Functions.constantSupplier("qux");
 
         ServiceDependency<Object> dependency = ServiceDependency.on(name);
 
-        doReturn(injection).when(builder).requires(name);
+        doReturn(injection1, injection2, injection3).when(builder).requires(name);
 
         dependency.accept(builder);
 
-        Assert.assertSame(injection.get(), dependency.get());
+        Assert.assertSame(injection1.get(), dependency.get());
+
+        ServiceDependency<Object> mapped = dependency.map(Functions.cast(Function.identity()));
+
+        Assert.assertSame(injection1.get(), mapped.get());
+
+        mapped.accept(builder);
+
+        Assert.assertSame(injection2.get(), mapped.get());
+        Assert.assertSame(injection2.get(), dependency.get());
+
+        ServiceDependency<String> cast = mapped.map(String.class::cast);
+
+        Assert.assertSame(injection2.get(), cast.get());
+
+        cast.accept(builder);
+
+        Assert.assertSame(injection3.get(), cast.get());
+        Assert.assertSame(injection3.get(), mapped.get());
+        Assert.assertSame(injection3.get(), dependency.get());
     }
 }