describe('DartEmitter', () => {
    var emitter: DartEmitter;
    var someVar: o.ReadVarExpr;

    beforeEach(() => {
      emitter = new DartEmitter();
      someVar = o.variable('someVar');
    });

    function emitStmt(stmt: o.Statement, exportedVars: string[] = null): string {
      if (isBlank(exportedVars)) {
        exportedVars = [];
      }
      return emitter.emitStatements(someModuleUrl, [stmt], exportedVars);
    }

    it('should declare variables', () => {
      expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt())).toEqual(`var someVar = 1;`);
      expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt(null, [o.StmtModifier.Final])))
          .toEqual(`final someVar = 1;`);
      expect(emitStmt(someVar.set(o.literal(1, new o.BuiltinType(o.BuiltinTypeName.Int,
                                                                 [o.TypeModifier.Const])))
                          .toDeclStmt(null, [o.StmtModifier.Final])))
          .toEqual(`const int someVar = 1;`);
      expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt(), ['someVar']))
          .toEqual(`var someVar = 1;`);
      expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt(o.INT_TYPE)))
          .toEqual(`int someVar = 1;`);
    });

    it('should read and write variables', () => {
      expect(emitStmt(someVar.toStmt())).toEqual(`someVar;`);
      expect(emitStmt(someVar.set(o.literal(1)).toStmt())).toEqual(`someVar = 1;`);
      expect(emitStmt(someVar.set(o.variable('someOtherVar').set(o.literal(1))).toStmt()))
          .toEqual(`someVar = (someOtherVar = 1);`);
    });

    it('should read and write keys', () => {
      expect(emitStmt(o.variable('someMap').key(o.variable('someKey')).toStmt()))
          .toEqual(`someMap[someKey];`);
      expect(emitStmt(o.variable('someMap').key(o.variable('someKey')).set(o.literal(1)).toStmt()))
          .toEqual(`someMap[someKey] = 1;`);
    });

    it('should read and write properties', () => {
      expect(emitStmt(o.variable('someObj').prop('someProp').toStmt()))
          .toEqual(`someObj.someProp;`);
      expect(emitStmt(o.variable('someObj').prop('someProp').set(o.literal(1)).toStmt()))
          .toEqual(`someObj.someProp = 1;`);
    });

    it('should invoke functions and methods and constructors', () => {
      expect(emitStmt(o.variable('someFn').callFn([o.literal(1)]).toStmt())).toEqual('someFn(1);');
      expect(emitStmt(o.variable('someObj').callMethod('someMethod', [o.literal(1)]).toStmt()))
          .toEqual('someObj.someMethod(1);');
      expect(emitStmt(o.variable('SomeClass').instantiate([o.literal(1)]).toStmt()))
          .toEqual('new SomeClass(1);');
    });

    it('should support builtin methods', () => {
      expect(emitStmt(o.variable('arr1')
                          .callMethod(o.BuiltinMethod.ConcatArray, [o.variable('arr2')])
                          .toStmt()))
          .toEqual('arr1..addAll(arr2);');

      expect(emitStmt(o.variable('observable')
                          .callMethod(o.BuiltinMethod.SubscribeObservable, [o.variable('listener')])
                          .toStmt()))
          .toEqual('observable.listen(listener);');

      expect(
          emitStmt(
              o.variable('fn').callMethod(o.BuiltinMethod.bind, [o.variable('someObj')]).toStmt()))
          .toEqual('fn;');
    });

    it('should support literals', () => {
      expect(emitStmt(o.literal(0).toStmt())).toEqual('0;');
      expect(emitStmt(o.literal(true).toStmt())).toEqual('true;');
      expect(emitStmt(o.literal('someStr').toStmt())).toEqual(`'someStr';`);
      expect(emitStmt(o.literal('$a').toStmt())).toEqual(`'\\$a';`);
      expect(emitStmt(o.literalArr([o.literal(1)]).toStmt())).toEqual(`[1];`);
      expect(emitStmt(o.literalMap([['someKey', o.literal(1)]]).toStmt()))
          .toEqual(`{'someKey': 1};`);
      expect(emitStmt(
                 o.literalMap([['someKey', o.literal(1)]], new o.MapType(o.NUMBER_TYPE)).toStmt()))
          .toEqual(`<String, num>{'someKey': 1};`);
    });

    it('should support external identifiers', () => {
      expect(emitStmt(o.importExpr(sameModuleIdentifier).toStmt())).toEqual('someLocalId;');
      expect(emitStmt(o.importExpr(externalModuleIdentifier).toStmt()))
          .toEqual([`import 'someOtherPath' as import0;`, `import0.someExternalId;`].join('\n'));
    });

    it('should support operators', () => {
      var lhs = o.variable('lhs');
      var rhs = o.variable('rhs');
      expect(emitStmt(someVar.cast(o.INT_TYPE).toStmt())).toEqual('(someVar as int);');
      expect(emitStmt(o.not(someVar).toStmt())).toEqual('!someVar;');
//.........这里部分代码省略.........

 function emitStmt(stmt: o.Statement, exportedVars: string[] = null): string {
   if (isBlank(exportedVars)) {
     exportedVars = [];
   }
   return emitter.emitStatements(someModuleUrl, [stmt], exportedVars);
 }