unit tests for nest based access control

core-java-11/src/main/java/com/baeldung/Outer.java

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+package com.baeldung;
+
+import java.lang.reflect.Method;
+
+public class Outer {
+
+  public void outerPublic() {
+  }
+
+  private void outerPrivate() {
+  }
+
+  class Inner {
+
+    public void innerPublic() {
+      outerPrivate();
+    }
+
+  	public void innerPublicReflection(Outer ob) throws Exception {
+      Method method = ob.getClass().getDeclaredMethod("outerPrivate");
+      method.invoke(ob);
+  	}
+  }
+}

core-java-11/src/test/java/com/baeldung/OuterUnitTest.java

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+package com.baeldung;
+
+import static org.hamcrest.CoreMatchers.is;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import org.junit.Test;
+
+public class OuterUnitTest {
+
+  private static final String NEST_HOST_NAME = "com.baeldung.Outer";
+
+  @Test
+  public void whenGetNestHostFromOuter_thenGetNestHost() {
+    is(Outer.class.getNestHost().getName()).equals(NEST_HOST_NAME);
+  }
+
+  @Test
+  public void whenGetNestHostFromInner_thenGetNestHost() {
+    is(Outer.Inner.class.getNestHost().getName()).equals(NEST_HOST_NAME);
+  }
+
+  @Test
+  public void whenCheckNestmatesForNestedClasses_thenGetTrue() {
+    is(Outer.Inner.class.isNestmateOf(Outer.class)).equals(true);
+  }
+
+  @Test
+  public void whenCheckNestmatesForUnrelatedClasses_thenGetFalse() {
+    is(Outer.Inner.class.isNestmateOf(Outer.class)).equals(false);
+  }
+
+  @Test
+  public void whenGetNestMembersForNestedClasses_thenGetAllNestedClasses() {
+    List<String> nestMembers = Arrays.stream(Outer.Inner.class.getNestMembers())
+        .map(Class::getName)
+        .collect(Collectors.toList());
+
+    is(nestMembers.size()).equals(2);
+
+    boolean containsOuter = nestMembers.stream()
+        .anyMatch("com.baeldung.Outer"::equals);
+    is(containsOuter).equals(true);
+
+    boolean containsInner = nestMembers.stream()
+        .anyMatch("com.baeldung.Outer$Inner"::equals);
+    is(containsInner).equals(true);
+  }
+}