code: package io.ray.runtime.functionmanager;
  
  import io.ray.api.function.RayFunc0;
  import io.ray.api.function.RayFunc1;
  import io.ray.api.id.JobId;
  import io.ray.runtime.functionmanager.FunctionManager.JobFunctionTable;
  import java.io.File;
  import java.nio.file.Files;
  import java.nio.file.Paths;
  import java.util.Collections;
  import java.util.Map;
  import javax.tools.JavaCompiler;
  import javax.tools.ToolProvider;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.lang3.tuple.ImmutablePair;
  import org.apache.commons.lang3.tuple.Pair;
  import org.testng.Assert;
  import org.testng.annotations.BeforeClass;
  import org.testng.annotations.Test;
  
  /** Tests for {@link FunctionManager} */
  public class FunctionManagerTest {
  
    public static Object foo() {
      return null;
    }
  
    public static class ParentClass {
  
      public Object foo() {
        return null;
      }
  
      public Object bar() {
        return null;
      }
    }
  
    public interface ChildClassInterface {
  
      default String interfaceName() {
        return getClass().getName();
      }
    }
  
    public static class ChildClass extends ParentClass implements ChildClassInterface {
  
      public ChildClass() {}
  
      @Override
      public Object bar() {
        return null;
      }
  
      public Object overloadFunction(int i) {
        return null;
      }
  
      public Object overloadFunction(double d) {
        return null;
      }
    }
  
    private static final JobId JOB_ID = JobId.fromInt(1);
  
    private static RayFunc0<Object> fooFunc;
    private static RayFunc1<ChildClass, Object> childClassBarFunc;
    private static RayFunc0<ChildClass> childClassConstructor;
    private static JavaFunctionDescriptor fooDescriptor;
    private static JavaFunctionDescriptor childClassBarDescriptor;
    private static JavaFunctionDescriptor childClassConstructorDescriptor;
    private static JavaFunctionDescriptor overloadFunctionDescriptorInt;
    private static JavaFunctionDescriptor overloadFunctionDescriptorDouble;
  
    @BeforeClass
    public static void beforeClass() {
      fooFunc = FunctionManagerTest::foo;
      childClassConstructor = ChildClass::new;
      childClassBarFunc = ChildClass::bar;
      fooDescriptor =
          new JavaFunctionDescriptor(
              FunctionManagerTest.class.getName(), "foo", "()Ljava/lang/Object;");
      childClassBarDescriptor =
          new JavaFunctionDescriptor(ChildClass.class.getName(), "bar", "()Ljava/lang/Object;");
      childClassConstructorDescriptor =
          new JavaFunctionDescriptor(
              ChildClass.class.getName(), FunctionManager.CONSTRUCTOR_NAME, "()V");
      overloadFunctionDescriptorInt =
          new JavaFunctionDescriptor(
              FunctionManagerTest.class.getName(), "overloadFunction", "(I)Ljava/lang/Object;");
      overloadFunctionDescriptorDouble =
          new JavaFunctionDescriptor(
              FunctionManagerTest.class.getName(), "overloadFunction", "(D)Ljava/lang/Object;");
    }
  
    @Test
    public void testGetFunctionFromRayFunc() {
      final FunctionManager functionManager = new FunctionManager(null);
      // Test normal function.
      RayFunction func = functionManager.getFunction(fooFunc);
      Assert.assertFalse(func.isConstructor());
      Assert.assertEquals(func.getFunctionDescriptor(), fooDescriptor);
  
      // Test actor method
      func = functionManager.getFunction(childClassBarFunc);
      Assert.assertFalse(func.isConstructor());
      Assert.assertEquals(func.getFunctionDescriptor(), childClassBarDescriptor);
  
      // Test actor constructor
      func = functionManager.getFunction(childClassConstructor);
      Assert.assertTrue(func.isConstructor());
      Assert.assertEquals(func.getFunctionDescriptor(), childClassConstructorDescriptor);
    }
  
    @Test
    public void testGetFunctionFromFunctionDescriptor() {
      final FunctionManager functionManager = new FunctionManager(null);
      // Test normal function.
      RayFunction func = functionManager.getFunction(fooDescriptor);
      Assert.assertFalse(func.isConstructor());
      Assert.assertEquals(func.getFunctionDescriptor(), fooDescriptor);
  
      // Test actor method
      func = functionManager.getFunction(childClassBarDescriptor);
      Assert.assertFalse(func.isConstructor());
      Assert.assertEquals(func.getFunctionDescriptor(), childClassBarDescriptor);
  
      // Test actor constructor
      func = functionManager.getFunction(childClassConstructorDescriptor);
      Assert.assertTrue(func.isConstructor());
      Assert.assertEquals(func.getFunctionDescriptor(), childClassConstructorDescriptor);
  
      // Test raise overload exception
      Assert.expectThrows(
          RuntimeException.class,
          () -> {
            functionManager.getFunction(
                new JavaFunctionDescriptor(
                    FunctionManagerTest.class.getName(), "overloadFunction", ""));
          });
    }
  
    @Test
    public void testInheritance() {
      final FunctionManager functionManager = new FunctionManager(null);
      // Check inheritance can work and FunctionManager can find method in parent class.
      fooDescriptor =
          new JavaFunctionDescriptor(ParentClass.class.getName(), "foo", "()Ljava/lang/Object;");
      Assert.assertEquals(
          functionManager.getFunction(fooDescriptor).executable.getDeclaringClass(),
          ParentClass.class);
      RayFunction fooFunc =
          functionManager.getFunction(
              new JavaFunctionDescriptor(ChildClass.class.getName(), "foo", "()Ljava/lang/Object;"));
      Assert.assertEquals(fooFunc.executable.getDeclaringClass(), ParentClass.class);
  
      // Check FunctionManager can use method in child class if child class methods overrides methods
      // in parent class.
      childClassBarDescriptor =
          new JavaFunctionDescriptor(ParentClass.class.getName(), "bar", "()Ljava/lang/Object;");
      Assert.assertEquals(
          functionManager.getFunction(childClassBarDescriptor).executable.getDeclaringClass(),
          ParentClass.class);
      RayFunction barFunc =
          functionManager.getFunction(
              new JavaFunctionDescriptor(ChildClass.class.getName(), "bar", "()Ljava/lang/Object;"));
      Assert.assertEquals(barFunc.executable.getDeclaringClass(), ChildClass.class);
  
      // Check interface default methods.
      RayFunction interfaceNameFunc =
          functionManager.getFunction(
              new JavaFunctionDescriptor(
                  ChildClass.class.getName(), "interfaceName", "()Ljava/lang/String;"));
      Assert.assertEquals(
          interfaceNameFunc.executable.getDeclaringClass(), ChildClassInterface.class);
    }
  
    @Test
    public void testLoadFunctionTableForClass() {
      JobFunctionTable functionTable = new JobFunctionTable(getClass().getClassLoader());
      Map<Pair<String, String>, Pair<RayFunction, Boolean>> res =
          functionTable.loadFunctionsForClass(ChildClass.class.getName());
      // The result should be 5 entries:
      //   1, the constructor with signature
      //   2, the constructor without signature
      //   3, bar with signature
      //   4, bar without signature
      //   5, bar with the number of signature acting as signature field (xlang)
      Assert.assertEquals(res.size(), 16);
      Assert.assertTrue(
          res.containsKey(
              ImmutablePair.of(childClassBarDescriptor.name, childClassBarDescriptor.signature)));
      Assert.assertTrue(
          res.containsKey(
              ImmutablePair.of(
                  childClassConstructorDescriptor.name, childClassConstructorDescriptor.signature)));
      Assert.assertTrue(res.containsKey(ImmutablePair.of(childClassBarDescriptor.name, "")));
      Assert.assertTrue(res.containsKey(ImmutablePair.of(childClassConstructorDescriptor.name, "")));
      Assert.assertTrue(
          res.containsKey(
              ImmutablePair.of(
                  overloadFunctionDescriptorInt.name, overloadFunctionDescriptorInt.signature)));
      Assert.assertTrue(
          res.containsKey(
              ImmutablePair.of(
                  overloadFunctionDescriptorDouble.name,
                  overloadFunctionDescriptorDouble.signature)));
      Assert.assertTrue(res.containsKey(ImmutablePair.of(overloadFunctionDescriptorInt.name, "")));
      Pair<String, String> overloadKey = ImmutablePair.of(overloadFunctionDescriptorInt.name, "");
      RayFunction func = res.get(overloadKey).getLeft();
      // The function is overloaded.
      Assert.assertTrue(res.containsKey(overloadKey));
      Assert.assertNull(func);
    }
  
    @Test
    public void testGetFunctionFromLocalResource() throws Exception {
      final String codeSearchPath = FileUtils.getTempDirectoryPath() + "/ray_test_resources/";
      File jobResourceDir = new File(codeSearchPath);
      FileUtils.deleteQuietly(jobResourceDir);
      jobResourceDir.mkdirs();
      jobResourceDir.deleteOnExit();
  
      String demoJavaFile = "";
      demoJavaFile += "public class DemoApp {\n";
      demoJavaFile += "  public static String hello() {\n";
      demoJavaFile += "    return \"hello\";\n";
      demoJavaFile += "  }\n";
      demoJavaFile += "}";
  
      // Write the demo java file to the job code search path.
      String javaFilePath = codeSearchPath + "/DemoApp.java";
      Files.write(Paths.get(javaFilePath), demoJavaFile.getBytes());
  
      // Compile the java file.
      JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
      int result = compiler.run(null, null, null, "-d", codeSearchPath, javaFilePath);
      if (result != 0) {
        throw new RuntimeException("Couldn't compile Demo.java.");
      }
  
      // Test loading the function.
      JavaFunctionDescriptor descriptor =
          new JavaFunctionDescriptor("DemoApp", "hello", "()Ljava/lang/String;");
      final FunctionManager functionManager =
          new FunctionManager(Collections.singletonList(codeSearchPath));
      RayFunction func = functionManager.getFunction(descriptor);
      Assert.assertEquals(func.getFunctionDescriptor(), descriptor);
    }
  }
  