dev/core/test/com/google/gwt/dev/jjs/impl/ControlFlowAnalyzerTest.java - gwt - Git at Google

 /*
  * Copyright 2008 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations under
  * the License.
  */
 package com.google.gwt.dev.jjs.impl;

 import com.google.gwt.core.ext.UnableToCompleteException;
 import com.google.gwt.dev.javac.testing.impl.MockJavaResource;
 import com.google.gwt.dev.jjs.ast.JField;
 import com.google.gwt.dev.jjs.ast.JMethod;
 import com.google.gwt.dev.jjs.ast.JNode;
 import com.google.gwt.dev.jjs.ast.JProgram;
 import com.google.gwt.dev.jjs.ast.JType;
 import com.google.gwt.dev.util.Empty;
 import com.google.gwt.thirdparty.guava.common.base.Joiner;
 import com.google.gwt.thirdparty.guava.common.collect.Sets;

 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;

 /**
  * Tests {@link ControlFlowAnalyzer}.
  */
 public class ControlFlowAnalyzerTest extends JJSTestBase {

   /**
    * Answers predicates about an analyzed program.
    */
   private static final class Result {
     private final ControlFlowAnalyzer cfa;
     private final JProgram program;

     public Result(JProgram program, ControlFlowAnalyzer cfa) {
       this.program = program;
       this.cfa = cfa;
     }

     public void assertOnlyFieldsWritten(String... expectedFields) {
       Set<JField> expectedSet = new HashSet<JField>();
       for (String expectedField : expectedFields) {
         JField field = findField(program, expectedField);
         assertNotNull(field);
         expectedSet.add(field);
       }
       assertEquals(expectedSet, cfa.getFieldsWritten());
     }

     public void assertOnlyInstantiatedTypes(String... expectedTypes) {
       Set<JType> expectedSet = Sets.newHashSet();
       for (String expectedType : expectedTypes) {
         JType type = findType(program, expectedType);
         assertNotNull(type);
         expectedSet.add(type);
       }
       assertEquals(expectedSet, cfa.getInstantiatedTypes());
     }

     public void assertOnlyLiveFieldsAndMethods(String... expected) {
       Set<JNode> expectedSet = new HashSet<JNode>();
       for (String expectedRef : expected) {
         JField field = findField(program, expectedRef);
         if (field != null) {
           expectedSet.add(field);
         } else {
           JMethod method = findQualifiedMethod(program, expectedRef);
           assertNotNull(method);
           expectedSet.add(method);
         }
       }
       assertEquals(expectedSet, cfa.getLiveFieldsAndMethods());
     }

     public void assertOnlyLiveStrings(String... expectedStrings) {
       Set<String> expectedSet = new HashSet<String>();
       Collections.addAll(expectedSet, expectedStrings);
       cfa.getLiveStrings();
       assertEquals(expectedSet, cfa.getLiveStrings());
     }
   }

   /**
    * Tests properties of an empty program.
    */
   public void testEmpty() throws Exception {
     Result result = analyzeSnippet("");
     result.assertOnlyFieldsWritten(Empty.STRINGS);
     result.assertOnlyInstantiatedTypes(Empty.STRINGS);
     result.assertOnlyLiveStrings(Empty.STRINGS);
   }

   /**
    * Tests that the JavaScriptObject type gets rescued in the three specific
    * circumstances where values can pass from JS into Java.
    */
   public void testRescueJavaScriptObjectFromJsni() throws Exception {
     addJsoResources();
     addOrReplaceResource("test.VirtualUpRef",
         "package test;",
         "import com.google.gwt.core.client.JavaScriptObject;",
         "final public class VirtualUpRef extends NonImplementor implements UpRefIntf {",
         "  protected VirtualUpRef() {}",
         "  public static native VirtualUpRef create() /*-{ return  {}; }-*/;",
         "}");
     addOrReplaceResource("test.Foo",
         "package test;",
         "import com.google.gwt.core.client.JavaScriptObject;",
         "public class Foo {",
         "  public static native JavaScriptObject returnsJso() /*-{ return {}; }-*/;",
         "  public static native void assignsJsoField() /*-{ @test.Foo::jsoField = {}; }-*/;",
         "  public static native void readsJsoField() /*-{ var x = @test.Foo::jsoField; }-*/;",
         "  public static native void passesJsoParam() /*-{ @test.Foo::calledFromJsni(Lcom/google/gwt/core/client/JavaScriptObject;)({}); }-*/;",
         "  private static JavaScriptObject jsoField = null;",
         "  private static void calledFromJsni(JavaScriptObject arg) { }",
         "  public static native JsoIntf returnsJsoIntf() /*-{ return {}; }-*/;",
         "  public static native SingleJso returnsSingleJso() /*-{ return {}; }-*/;",
         "}");
     addSnippetImport("test.Foo");

     analyzeSnippet("").assertOnlyInstantiatedTypes(Empty.STRINGS);

     // Returning a JSO from a JSNI method rescues.
     analyzeSnippet("Foo.returnsJso();").assertOnlyInstantiatedTypes(
         "JavaScriptObject", "Object");

     // Assigning into a JSO field from a JSNI method rescues.
     analyzeSnippet("Foo.assignsJsoField();").assertOnlyInstantiatedTypes(
         "JavaScriptObject", "Object");

     // Passing from Java to JS via a JSNI field read should NOT rescue.
     analyzeSnippet("Foo.readsJsoField();").assertOnlyInstantiatedTypes(
         Empty.STRINGS);

     // Passing a parameter from JS to Java rescues.
     analyzeSnippet("Foo.passesJsoParam();").assertOnlyInstantiatedTypes(
         "JavaScriptObject", "Object");

     // Returning a JSO subType instantiates it
     analyzeSnippet("Foo.returnsSingleJso();").assertOnlyInstantiatedTypes(
         "SingleJso", "JavaScriptObject", "Object", "JsoIntf");

     // Returning a JSO SingleJsoImpl instantiates it and the implementor
     analyzeSnippet("Foo.returnsJsoIntf();").assertOnlyInstantiatedTypes(
         "SingleJso", "JavaScriptObject", "Object", "JsoIntf");

     // A virtual upref should still be rescued
     analyzeSnippet("VirtualUpRef.create().getFoo();").assertOnlyInstantiatedTypes(
         "VirtualUpRef", "NonImplementor", "JavaScriptObject", "Object", "UpRefIntf");

     // and its methods
     analyzeSnippet("VirtualUpRef.create().getFoo();").assertOnlyLiveFieldsAndMethods(
         "VirtualUpRef.$clinit", "VirtualUpRef.create", "VirtualUpRef.getFoo",
         "NonImplementor.$clinit","NonImplementor.getFoo",
         "UpRefIntf.$clinit",
         "JavaScriptObject.$clinit",
         "EntryPoint.$clinit",
         "EntryPoint.onModuleLoad",
         "Object.$clinit");
   }

   /**
    * Tests that certain Java arrays are rescued if returned from JSNI code. Arrays that are rescued
    * if returned from JSNI: code whose leaf types are either primitive or types that might be
    * instantiated in JSNI.
    */
   public void testRescueArraysFromJSNI() throws Exception {
     addOrReplaceResource("test.Foo",
         "package test;", "public class Foo {",
         "  public static native int[] create_array() /*-{ return {}; }-*/;",
         "  public static native int[][] create_2d_array() /*-{ return {}; }-*/;",
         "}");
     addSnippetImport("test.Foo");

     analyzeSnippet("").assertOnlyInstantiatedTypes(Empty.STRINGS);

     // Returning a JSO from a JSNI method rescues.
     analyzeSnippet("Foo.create_array();").assertOnlyInstantiatedTypes(
         "int[]", "Object");

     // Returning a JSO from a JSNI method rescues.
     analyzeSnippet("Foo.create_2d_array();").assertOnlyInstantiatedTypes(
         "int[][]", "Object[]", "Object");
   }

   public void testRescueJavaScriptObjectReturnedFromExternallyImplementedMethod() throws Exception {
     addJsoResources();
     addSnippetImport("test.Test");

     addOrReplaceResource("test.Test",
         "package test;",
         "import jsinterop.annotations.JsMethod;",
         "public class Test {",
         "  @JsMethod",
         "  public static native JsoIntf returnsJsoInterface();",
         "}"
     );
     analyzeSnippet("Test.returnsJsoInterface();").assertOnlyInstantiatedTypes(
         "JsoIntf", "SingleJso", "JavaScriptObject", "Object");

     addOrReplaceResource("test.Test",
         "package test;",
         "import jsinterop.annotations.JsMethod;",
         "public class Test {",
         "  @JsMethod",
         "  public static native SingleJso returnsJso();",
         "}"
     );
     analyzeSnippet("Test.returnsJso();").assertOnlyInstantiatedTypes(
         "JsoIntf", "SingleJso", "JavaScriptObject", "Object");
   }

   public void testRescueJavaScriptObjectParameterToJsInteropEntryPoint() throws Exception {
     addJsoResources();
     addSnippetImport("test.Test");

     addOrReplaceResource("test.Test",
         "package test;",
         "import jsinterop.annotations.JsMethod;",
         "public class Test {",
         "  public static void receivesJsoInterface(JsoIntf i) {};",
         "}"
     );
     analyzeSnippet("Test.receivesJsoInterface(null);").assertOnlyInstantiatedTypes(
         Empty.STRINGS);

     addOrReplaceResource("test.Test",
         "package test;",
         "import jsinterop.annotations.JsMethod;",
         "public class Test {",
         "  @JsMethod",
         "  public static void receivesJsoInterface(JsoIntf i) {};",
         "}"
     );
     analyzeSnippet("Test.receivesJsoInterface(null);").assertOnlyInstantiatedTypes(
         "JsoIntf", "SingleJso", "JavaScriptObject", "Object");
   }

     /**
      * Tests that the JavaScriptObject type gets rescued in the three specific
      * circumstances where values can pass from JS into Java.
      */
   public void testRescueJavaScriptObjectReturnedFromFieldReference() throws Exception {
     addJsoResources();
     addSnippetImport("test.Test");

     addOrReplaceResource("test.Test",
         "package test;",
         "import jsinterop.annotations.JsType;",
         "@JsType(isNative = true)",
         "public class Test {",
         "  public static JsoIntf field;",
         "}"
     );
     analyzeSnippet("Test.field.hashCode();").assertOnlyInstantiatedTypes(
         "JsoIntf", "SingleJso", "JavaScriptObject", "Object",
         // These are all live because of the method Test.toString can be referenced externally.
         "String", "Comparable", "CharSequence", "Serializable");

     addOrReplaceResource("test.Test",
         "package test;",
         "import jsinterop.annotations.JsType;",
         "@JsType(isNative = true)",
         "public class Test {",
         "  public static SingleJso field;",
         "}"
     );
     analyzeSnippet("Test.field.hashCode();").assertOnlyInstantiatedTypes(
         "JsoIntf", "SingleJso", "JavaScriptObject", "Object",
         // These are all live because of the method Test.toString can be referenced externally.
         "String", "Comparable", "CharSequence", "Serializable");
   }

   private void addOrReplaceResource(String qualifiedTypeName, final String... source) {
     sourceOracle.addOrReplace(
         new MockJavaResource(qualifiedTypeName) {
           @Override
           public CharSequence getContent() {
             return Joiner.on("\n").join(source);
           }
         });
     }

   private void addJsoResources() {
     addOrReplaceResource("test.JsoIntf",
         "package test;",
         "import com.google.gwt.core.client.JavaScriptObject;",
         "public interface JsoIntf {",
         "  public int getAny();",
         "}");
     addOrReplaceResource("test.UpRefIntf",
         "package test;",
         "import com.google.gwt.core.client.JavaScriptObject;",
         "public interface UpRefIntf {",
         "  public int getFoo();",
         "}");
     addOrReplaceResource("test.NonImplementor",
         "package test;",
         "import com.google.gwt.core.client.JavaScriptObject;",
         "public class NonImplementor extends JavaScriptObject {",
         "  protected NonImplementor() {}",
         "  final public native int getFoo() /*-{ return 0; }-*/;",
         "}");
     addOrReplaceResource("test.SingleJso",
         "package test;",
         "import com.google.gwt.core.client.JavaScriptObject;",
         "final public class SingleJso extends JavaScriptObject implements JsoIntf {",
         "  protected SingleJso() {}",
         "  public native int getAny() /*-{ return 1; }-*/;",
         "}");
   }

   private Result analyzeSnippet(String codeSnippet)
       throws UnableToCompleteException {
     JProgram program = compileSnippet("void", codeSnippet, true);
     ControlFlowAnalyzer cfa = new ControlFlowAnalyzer(program);
     cfa.traverseFrom(findMainMethod(program));
     return new Result(program, cfa);
   }

 }
	/*
	* Copyright 2008 Google Inc.
	*
	* Licensed under the Apache License, Version 2.0 (the "License"); you may not
	* use this file except in compliance with the License. You may obtain a copy of
	* the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	* License for the specific language governing permissions and limitations under
	* the License.
	*/
	package com.google.gwt.dev.jjs.impl;

	import com.google.gwt.core.ext.UnableToCompleteException;
	import com.google.gwt.dev.javac.testing.impl.MockJavaResource;
	import com.google.gwt.dev.jjs.ast.JField;
	import com.google.gwt.dev.jjs.ast.JMethod;
	import com.google.gwt.dev.jjs.ast.JNode;
	import com.google.gwt.dev.jjs.ast.JProgram;
	import com.google.gwt.dev.jjs.ast.JType;
	import com.google.gwt.dev.util.Empty;
	import com.google.gwt.thirdparty.guava.common.base.Joiner;
	import com.google.gwt.thirdparty.guava.common.collect.Sets;

	import java.util.Collections;
	import java.util.HashSet;
	import java.util.Set;

	/**
	* Tests {@link ControlFlowAnalyzer}.
	*/
	public class ControlFlowAnalyzerTest extends JJSTestBase {

	/**
	* Answers predicates about an analyzed program.
	*/
	private static final class Result {
	private final ControlFlowAnalyzer cfa;
	private final JProgram program;

	public Result(JProgram program, ControlFlowAnalyzer cfa) {
	this.program = program;
	this.cfa = cfa;
	}

	public void assertOnlyFieldsWritten(String... expectedFields) {
	Set<JField> expectedSet = new HashSet<JField>();
	for (String expectedField : expectedFields) {
	JField field = findField(program, expectedField);
	assertNotNull(field);
	expectedSet.add(field);
	}
	assertEquals(expectedSet, cfa.getFieldsWritten());
	}

	public void assertOnlyInstantiatedTypes(String... expectedTypes) {
	Set<JType> expectedSet = Sets.newHashSet();
	for (String expectedType : expectedTypes) {
	JType type = findType(program, expectedType);
	assertNotNull(type);
	expectedSet.add(type);
	}
	assertEquals(expectedSet, cfa.getInstantiatedTypes());
	}

	public void assertOnlyLiveFieldsAndMethods(String... expected) {
	Set<JNode> expectedSet = new HashSet<JNode>();
	for (String expectedRef : expected) {
	JField field = findField(program, expectedRef);
	if (field != null) {
	expectedSet.add(field);
	} else {
	JMethod method = findQualifiedMethod(program, expectedRef);
	assertNotNull(method);
	expectedSet.add(method);
	}
	}
	assertEquals(expectedSet, cfa.getLiveFieldsAndMethods());
	}

	public void assertOnlyLiveStrings(String... expectedStrings) {
	Set<String> expectedSet = new HashSet<String>();
	Collections.addAll(expectedSet, expectedStrings);
	cfa.getLiveStrings();
	assertEquals(expectedSet, cfa.getLiveStrings());
	}
	}

	/**
	* Tests properties of an empty program.
	*/
	public void testEmpty() throws Exception {
	Result result = analyzeSnippet("");
	result.assertOnlyFieldsWritten(Empty.STRINGS);
	result.assertOnlyInstantiatedTypes(Empty.STRINGS);
	result.assertOnlyLiveStrings(Empty.STRINGS);
	}

	/**
	* Tests that the JavaScriptObject type gets rescued in the three specific
	* circumstances where values can pass from JS into Java.
	*/
	public void testRescueJavaScriptObjectFromJsni() throws Exception {
	addJsoResources();
	addOrReplaceResource("test.VirtualUpRef",
	"package test;",
	"import com.google.gwt.core.client.JavaScriptObject;",
	"final public class VirtualUpRef extends NonImplementor implements UpRefIntf {",
	" protected VirtualUpRef() {}",
	" public static native VirtualUpRef create() /-{ return {}; }-/;",
	"}");
	addOrReplaceResource("test.Foo",
	"package test;",
	"import com.google.gwt.core.client.JavaScriptObject;",
	"public class Foo {",
	" public static native JavaScriptObject returnsJso() /-{ return {}; }-/;",
	" public static native void assignsJsoField() /-{ @test.Foo::jsoField = {}; }-/;",
	" public static native void readsJsoField() /-{ var x = @test.Foo::jsoField; }-/;",
	" public static native void passesJsoParam() /-{ @test.Foo::calledFromJsni(Lcom/google/gwt/core/client/JavaScriptObject;)({}); }-/;",
	" private static JavaScriptObject jsoField = null;",
	" private static void calledFromJsni(JavaScriptObject arg) { }",
	" public static native JsoIntf returnsJsoIntf() /-{ return {}; }-/;",
	" public static native SingleJso returnsSingleJso() /-{ return {}; }-/;",
	"}");
	addSnippetImport("test.Foo");

	analyzeSnippet("").assertOnlyInstantiatedTypes(Empty.STRINGS);

	// Returning a JSO from a JSNI method rescues.
	analyzeSnippet("Foo.returnsJso();").assertOnlyInstantiatedTypes(
	"JavaScriptObject", "Object");

	// Assigning into a JSO field from a JSNI method rescues.
	analyzeSnippet("Foo.assignsJsoField();").assertOnlyInstantiatedTypes(
	"JavaScriptObject", "Object");

	// Passing from Java to JS via a JSNI field read should NOT rescue.
	analyzeSnippet("Foo.readsJsoField();").assertOnlyInstantiatedTypes(
	Empty.STRINGS);

	// Passing a parameter from JS to Java rescues.
	analyzeSnippet("Foo.passesJsoParam();").assertOnlyInstantiatedTypes(
	"JavaScriptObject", "Object");

	// Returning a JSO subType instantiates it
	analyzeSnippet("Foo.returnsSingleJso();").assertOnlyInstantiatedTypes(
	"SingleJso", "JavaScriptObject", "Object", "JsoIntf");

	// Returning a JSO SingleJsoImpl instantiates it and the implementor
	analyzeSnippet("Foo.returnsJsoIntf();").assertOnlyInstantiatedTypes(
	"SingleJso", "JavaScriptObject", "Object", "JsoIntf");

	// A virtual upref should still be rescued
	analyzeSnippet("VirtualUpRef.create().getFoo();").assertOnlyInstantiatedTypes(
	"VirtualUpRef", "NonImplementor", "JavaScriptObject", "Object", "UpRefIntf");

	// and its methods
	analyzeSnippet("VirtualUpRef.create().getFoo();").assertOnlyLiveFieldsAndMethods(
	"VirtualUpRef.$clinit", "VirtualUpRef.create", "VirtualUpRef.getFoo",
	"NonImplementor.$clinit","NonImplementor.getFoo",
	"UpRefIntf.$clinit",
	"JavaScriptObject.$clinit",
	"EntryPoint.$clinit",
	"EntryPoint.onModuleLoad",
	"Object.$clinit");
	}

	/**
	* Tests that certain Java arrays are rescued if returned from JSNI code. Arrays that are rescued
	* if returned from JSNI: code whose leaf types are either primitive or types that might be
	* instantiated in JSNI.
	*/
	public void testRescueArraysFromJSNI() throws Exception {
	addOrReplaceResource("test.Foo",
	"package test;", "public class Foo {",
	" public static native int[] create_array() /-{ return {}; }-/;",
	" public static native int[][] create_2d_array() /-{ return {}; }-/;",
	"}");
	addSnippetImport("test.Foo");

	analyzeSnippet("").assertOnlyInstantiatedTypes(Empty.STRINGS);

	// Returning a JSO from a JSNI method rescues.
	analyzeSnippet("Foo.create_array();").assertOnlyInstantiatedTypes(
	"int[]", "Object");

	// Returning a JSO from a JSNI method rescues.
	analyzeSnippet("Foo.create_2d_array();").assertOnlyInstantiatedTypes(
	"int[][]", "Object[]", "Object");
	}

	public void testRescueJavaScriptObjectReturnedFromExternallyImplementedMethod() throws Exception {
	addJsoResources();
	addSnippetImport("test.Test");

	addOrReplaceResource("test.Test",
	"package test;",
	"import jsinterop.annotations.JsMethod;",
	"public class Test {",
	" @JsMethod",
	" public static native JsoIntf returnsJsoInterface();",
	"}"
	);
	analyzeSnippet("Test.returnsJsoInterface();").assertOnlyInstantiatedTypes(
	"JsoIntf", "SingleJso", "JavaScriptObject", "Object");

	addOrReplaceResource("test.Test",
	"package test;",
	"import jsinterop.annotations.JsMethod;",
	"public class Test {",
	" @JsMethod",
	" public static native SingleJso returnsJso();",
	"}"
	);
	analyzeSnippet("Test.returnsJso();").assertOnlyInstantiatedTypes(
	"JsoIntf", "SingleJso", "JavaScriptObject", "Object");
	}

	public void testRescueJavaScriptObjectParameterToJsInteropEntryPoint() throws Exception {
	addJsoResources();
	addSnippetImport("test.Test");

	addOrReplaceResource("test.Test",
	"package test;",
	"import jsinterop.annotations.JsMethod;",
	"public class Test {",
	" public static void receivesJsoInterface(JsoIntf i) {};",
	"}"
	);
	analyzeSnippet("Test.receivesJsoInterface(null);").assertOnlyInstantiatedTypes(
	Empty.STRINGS);

	addOrReplaceResource("test.Test",
	"package test;",
	"import jsinterop.annotations.JsMethod;",
	"public class Test {",
	" @JsMethod",
	" public static void receivesJsoInterface(JsoIntf i) {};",
	"}"
	);
	analyzeSnippet("Test.receivesJsoInterface(null);").assertOnlyInstantiatedTypes(
	"JsoIntf", "SingleJso", "JavaScriptObject", "Object");
	}

	/**
	* Tests that the JavaScriptObject type gets rescued in the three specific
	* circumstances where values can pass from JS into Java.
	*/
	public void testRescueJavaScriptObjectReturnedFromFieldReference() throws Exception {
	addJsoResources();
	addSnippetImport("test.Test");

	addOrReplaceResource("test.Test",
	"package test;",
	"import jsinterop.annotations.JsType;",
	"@JsType(isNative = true)",
	"public class Test {",
	" public static JsoIntf field;",
	"}"
	);
	analyzeSnippet("Test.field.hashCode();").assertOnlyInstantiatedTypes(
	"JsoIntf", "SingleJso", "JavaScriptObject", "Object",
	// These are all live because of the method Test.toString can be referenced externally.
	"String", "Comparable", "CharSequence", "Serializable");

	addOrReplaceResource("test.Test",
	"package test;",
	"import jsinterop.annotations.JsType;",
	"@JsType(isNative = true)",
	"public class Test {",
	" public static SingleJso field;",
	"}"
	);
	analyzeSnippet("Test.field.hashCode();").assertOnlyInstantiatedTypes(
	"JsoIntf", "SingleJso", "JavaScriptObject", "Object",
	// These are all live because of the method Test.toString can be referenced externally.
	"String", "Comparable", "CharSequence", "Serializable");
	}

	private void addOrReplaceResource(String qualifiedTypeName, final String... source) {
	sourceOracle.addOrReplace(
	new MockJavaResource(qualifiedTypeName) {
	@Override
	public CharSequence getContent() {
	return Joiner.on("\n").join(source);
	}
	});
	}

	private void addJsoResources() {
	addOrReplaceResource("test.JsoIntf",
	"package test;",
	"import com.google.gwt.core.client.JavaScriptObject;",
	"public interface JsoIntf {",
	" public int getAny();",
	"}");
	addOrReplaceResource("test.UpRefIntf",
	"package test;",
	"import com.google.gwt.core.client.JavaScriptObject;",
	"public interface UpRefIntf {",
	" public int getFoo();",
	"}");
	addOrReplaceResource("test.NonImplementor",
	"package test;",
	"import com.google.gwt.core.client.JavaScriptObject;",
	"public class NonImplementor extends JavaScriptObject {",
	" protected NonImplementor() {}",
	" final public native int getFoo() /-{ return 0; }-/;",
	"}");
	addOrReplaceResource("test.SingleJso",
	"package test;",
	"import com.google.gwt.core.client.JavaScriptObject;",
	"final public class SingleJso extends JavaScriptObject implements JsoIntf {",
	" protected SingleJso() {}",
	" public native int getAny() /-{ return 1; }-/;",
	"}");
	}

	private Result analyzeSnippet(String codeSnippet)
	throws UnableToCompleteException {
	JProgram program = compileSnippet("void", codeSnippet, true);
	ControlFlowAnalyzer cfa = new ControlFlowAnalyzer(program);
	cfa.traverseFrom(findMainMethod(program));
	return new Result(program, cfa);
	}

	}