Add java.lang.Module API code

core-java-9/src/test/java/com/baeldung/java9/modules/ModuleAPIUnitTest.java

@@ -0,0 +1,199 @@
+package com.baeldung.java9.modules;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.nullValue;
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.hamcrest.collection.IsEmptyCollection.empty;
+import static org.junit.Assert.*;
+
+import java.lang.module.ModuleDescriptor;
+import java.lang.module.ModuleDescriptor.*;
+import java.sql.Date;
+import java.sql.Driver;
+import java.util.HashMap;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class ModuleAPIUnitTest {
+
+    public static final String JAVA_BASE_MODULE_NAME = "java.base";
+
+    private Module javaBaseModule;
+    private Module javaSqlModule;
+    private Module module;
+
+    @Before
+    public void setUp() {
+        Class<HashMap> hashMapClass = HashMap.class;
+        javaBaseModule = hashMapClass.getModule();
+
+        Class<Date> dateClass = Date.class;
+        javaSqlModule = dateClass.getModule();
+
+        Class<Person> personClass = Person.class;
+        module = personClass.getModule();
+    }
+
+    @Test
+    public void whenCheckingIfNamed_thenModuleIsNamed() {
+        assertThat(javaBaseModule.isNamed(), is(true));
+        assertThat(javaBaseModule.getName(), is(JAVA_BASE_MODULE_NAME));
+    }
+
+    @Test
+    public void whenCheckingIfNamed_thenModuleIsUnnamed() {
+        assertThat(module.isNamed(), is(false));
+        assertThat(module.getName(), is(nullValue()));
+    }
+
+    @Test
+    public void whenExtractingPackagesContainedInAModule_thenModuleContainsOnlyFewOfThem() {
+        assertTrue(javaBaseModule.getPackages().contains("java.lang.annotation"));
+        assertFalse(javaBaseModule.getPackages().contains("java.sql"));
+    }
+
+    @Test
+    public void whenRetrievingClassLoader_thenClassLoaderIsReturned() {
+        assertThat(
+          module.getClassLoader().getClass().getName(),
+          is("jdk.internal.loader.ClassLoaders$AppClassLoader")
+        );
+    }
+
+    @Test
+    public void whenGettingAnnotationsPresentOnAModule_thenNoAnnotationsArePresent() {
+        assertThat(javaBaseModule.getAnnotations().length, is(0));
+    }
+
+    @Test
+    public void whenGettingLayerOfAModule_thenModuleLayerInformationAreAvailable() {
+        ModuleLayer javaBaseModuleLayer = javaBaseModule.getLayer();
+
+        assertTrue(javaBaseModuleLayer.configuration().findModule(JAVA_BASE_MODULE_NAME).isPresent());
+        assertThat(javaBaseModuleLayer.configuration().modules().size(), is(78));
+        assertTrue(javaBaseModuleLayer.parents().get(0).configuration().parents().isEmpty());
+    }
+
+    @Test
+    public void whenRetrievingModuleDescriptor_thenTypeOfModuleIsInferred() {
+        ModuleDescriptor javaBaseModuleDescriptor = javaBaseModule.getDescriptor();
+        ModuleDescriptor javaSqlModuleDescriptor = javaSqlModule.getDescriptor();
+
+        assertFalse(javaBaseModuleDescriptor.isAutomatic());
+        assertFalse(javaBaseModuleDescriptor.isOpen());
+        assertFalse(javaSqlModuleDescriptor.isAutomatic());
+        assertFalse(javaSqlModuleDescriptor.isOpen());
+    }
+
+    @Test
+    public void givenModuleName_whenBuildingModuleDescriptor_thenBuilt() {
+        Builder moduleBuilder = ModuleDescriptor.newModule("baeldung.base");
+
+        ModuleDescriptor moduleDescriptor = moduleBuilder.build();
+
+        assertThat(moduleDescriptor.name(), is("baeldung.base"));
+    }
+
+    @Test
+    public void givenModules_whenAccessingModuleDescriptorRequires_thenRequiresAreReturned() {
+        Set<Requires> javaBaseRequires = javaBaseModule.getDescriptor().requires();
+        Set<Requires> javaSqlRequires = javaSqlModule.getDescriptor().requires();
+
+        Set<String> javaSqlRequiresNames = javaSqlRequires.stream()
+          .map(Requires::name)
+          .collect(Collectors.toSet());
+
+        assertThat(javaBaseRequires, empty());
+        assertThat(javaSqlRequires.size(), is(3));
+        assertThat(javaSqlRequiresNames, containsInAnyOrder("java.base", "java.xml", "java.logging"));
+    }
+
+    @Test
+    public void givenModules_whenAccessingModuleDescriptorProvides_thenProvidesAreReturned() {
+        Set<Provides> javaBaseProvides = javaBaseModule.getDescriptor().provides();
+        Set<Provides> javaSqlProvides = javaSqlModule.getDescriptor().provides();
+
+        Set<String> javaBaseProvidesService = javaBaseProvides.stream()
+                .map(Provides::service)
+                .collect(Collectors.toSet());
+
+        assertThat(javaBaseProvidesService, contains("java.nio.file.spi.FileSystemProvider"));
+        assertThat(javaSqlProvides, empty());
+    }
+
+    @Test
+    public void givenModules_whenAccessingModuleDescriptorExports_thenExportsAreReturned() {
+        Set<Exports> javaBaseExports = javaBaseModule.getDescriptor().exports();
+        Set<Exports> javaSqlExports = javaSqlModule.getDescriptor().exports();
+
+        Set<String> javaSqlExportsSource = javaSqlExports.stream()
+          .map(Exports::source)
+          .collect(Collectors.toSet());
+
+        assertThat(javaBaseExports.size(), is(108));
+        assertThat(javaSqlExports.size(), is(3));
+        assertThat(javaSqlExportsSource, containsInAnyOrder("java.sql", "javax.transaction.xa", "javax.sql"));
+    }
+
+    @Test
+    public void givenModules_whenAccessingModuleDescriptorUses_thenUsesAreReturned() {
+        Set<String> javaBaseUses = javaBaseModule.getDescriptor().uses();
+        Set<String> javaSqlUses = javaSqlModule.getDescriptor().uses();
+
+        assertThat(javaBaseUses.size(), is(34));
+        assertThat(javaSqlUses, contains("java.sql.Driver"));
+    }
+
+    @Test
+    public void givenModules_whenAccessingModuleDescriptorOpen_thenOpenAreReturned() {
+        Set<Opens> javaBaseUses = javaBaseModule.getDescriptor().opens();
+        Set<Opens> javaSqlUses = javaSqlModule.getDescriptor().opens();
+
+        assertThat(javaBaseUses, empty());
+        assertThat(javaSqlUses, empty());
+    }
+
+    @Test
+    public void whenAddingReadsToAModule_thenModuleCanReadNewModule() {
+        Module updatedModule = module.addReads(javaSqlModule);
+
+        assertTrue(updatedModule.canRead(javaSqlModule));
+    }
+
+    @Test
+    public void whenExportingPackage_thenPackageIsExported() {
+        Module updatedModule = module.addExports("com.baeldung.java9.modules", javaSqlModule);
+
+        assertTrue(updatedModule.isExported("com.baeldung.java9.modules"));
+    }
+
+    @Test
+    public void whenOpeningAModulePackage_thenPackagedIsOpened() {
+        Module updatedModule = module.addOpens("com.baeldung.java9.modules", javaSqlModule);
+
+        assertTrue(updatedModule.isOpen("com.baeldung.java9.modules", javaSqlModule));
+    }
+
+    @Test
+    public void whenAddingUsesToModule_thenUsesIsAdded() {
+        Module updatedModule = module.addUses(Driver.class);
+
+        assertTrue(updatedModule.canUse(Driver.class));
+    }
+
+    private class Person {
+        private String name;
+
+        public Person(String name) {
+            this.name = name;
+        }
+
+        public String getName() {
+            return name;
+        }
+    }
+}